In early June 2008 I bought an old Vigor Burnout Furnace (model CA 1065)
for $95 from a seller on Craigslist. The furnace appears to have been
built in 1979, but does work.

The furnace came with a so-called "infinite" control, which is an
electromechanical contraption with ten intensity settings (from mostly
off to always on). What varies is the average duty cycle of power on
versus power off. There is no feedback control. This is far too crude
and clumsy to heat-treat metals, so I decided to add an electronic
furnace controller.

So I bought a 1/32 DIN PID controller and solid-state relay (SSR) from
Omega Engineering. I'm still using the thermocouple that came with the
furnace, but not for long, as the original thermocouple is old and
oxidized and a bit off. But it works well enough for now, and will hold
to within a degree or so of a temperature, far better than is required
in heat treating of say O1 oil hardening steel or A2 air hardening steel.

The big problem was that the original design didn't have a big enough
heatsink on the SSR, and there wasn't enough thermal isolation between
the control box and the furnace box, so the controller and SSR both got
too hot when the furnace went to max temperature (about 990 degrees C).
The controller would get to 50 degrees C, which is right at its upper
temperature limit, which is asking for reliability problems. The SSR
would get almost to 60 degrees C, which is also in its range, but asking
for trouble.

So, for the SSR I got a large heatsink from Omega, which dropped the
temperature to 36 degrees C.

The controller was a bit more difficult. I ended up making a set of
spacers from 0.5" diameter gummy aluminum rod on the lathe, and cutting
two aluminum plates with clearance holes, all to space the control box
away from the body of the furnace, with two parallel plates between,
thermally isolating control box from furnace body. Now, the PID
controller temperature is 35 degrees C max.

At this point, I have declared victory, as 35 or 36 degrees C is low
enough that reliability won't be much reduced.

Joe Gwinn

Joseph Gwinn wrote:
In early June 2008 I bought an old Vigor Burnout Furnace (model CA 1065)
for $95 from a seller on Craigslist. The furnace appears to have been
built in 1979, but does work.

The furnace came with a so-called "infinite" control, which is an
electromechanical contraption with ten intensity settings (from mostly
off to always on). What varies is the average duty cycle of power on
versus power off. There is no feedback control. This is far too crude
and clumsy to heat-treat metals, so I decided to add an electronic
furnace controller.

So I bought a 1/32 DIN PID controller and solid-state relay (SSR) from
Omega Engineering. I'm still using the thermocouple that came with the
furnace, but not for long, as the original thermocouple is old and
oxidized and a bit off. But it works well enough for now, and will hold
to within a degree or so of a temperature, far better than is required
in heat treating of say O1 oil hardening steel or A2 air hardening steel.

The big problem was that the original design didn't have a big enough
heatsink on the SSR, and there wasn't enough thermal isolation between
the control box and the furnace box, so the controller and SSR both got
too hot when the furnace went to max temperature (about 990 degrees C).
The controller would get to 50 degrees C, which is right at its upper
temperature limit, which is asking for reliability problems. The SSR
would get almost to 60 degrees C, which is also in its range, but asking
for trouble.

So, for the SSR I got a large heatsink from Omega, which dropped the
temperature to 36 degrees C.

The controller was a bit more difficult. I ended up making a set of
spacers from 0.5" diameter gummy aluminum rod on the lathe, and cutting
two aluminum plates with clearance holes, all to space the control box
away from the body of the furnace, with two parallel plates between,
thermally isolating control box from furnace body. Now, the PID
controller temperature is 35 degrees C max.

At this point, I have declared victory, as 35 or 36 degrees C is low
enough that reliability won't be much reduced.

Joe Gwinn

I've got an 18" 4kW top loading ceramic kiln that I use for heat
treatment and other things and I similarly fitted a temperature
controller to it. It still has the 2 "energy controllers" fitted, one
for each bank but they are normally set to max or off if one bank is not
needed.
I added a thermocouple to the kiln and connector into the box on the
side. The temperature controller is housed in a separate box with tails
out the back and mains plugs on the end so I can use it for controlling
other things if required, it also allows it to be placed away from the
heat. The thermocouple lead currently plugs into the front of the
controller box. The finned heat sink is about 3"H x 3"W x 1.2"D and gets
warm to the touch when running max duty, like when firing to 1200C, but
very acceptable.


One of these days I'll add a temperature controller I have to my small
Gallenkamp heat treatment furnace as the energy controller on that is a
pain, but the thermocouple read-out is accurate from checks I've done.

In article ,
David Billington wrote:

Joseph Gwinn wrote:
In early June 2008 I bought an old Vigor Burnout Furnace (model CA 1065)
for $95 from a seller on Craigslist. The furnace appears to have been
built in 1979, but does work.

[snip]

So I bought a 1/32 DIN PID controller and solid-state relay (SSR) from
Omega Engineering. I'm still using the thermocouple that came with the
furnace, but not for long, as the original thermocouple is old and
oxidized and a bit off. But it works well enough for now, and will hold
to within a degree or so of a temperature, far better than is required
in heat treating of say O1 oil hardening steel or A2 air hardening steel.

The big problem was that the original design didn't have a big enough
heatsink on the SSR, and there wasn't enough thermal isolation between
the control box and the furnace box, so the controller and SSR both got
too hot when the furnace went to max temperature (about 990 degrees C).
The controller would get to 50 degrees C, which is right at its upper
temperature limit, which is asking for reliability problems. The SSR
would get almost to 60 degrees C, which is also in its range, but asking
for trouble.

So, for the SSR I got a large heatsink from Omega, which dropped the
temperature to 36 degrees C.

[snip]

At this point, I have declared victory, as 35 or 36 degrees C is low
enough that reliability won't be much reduced.

Joe Gwinn

I've got an 18" 4kW top loading ceramic kiln that I use for heat
treatment and other things and I similarly fitted a temperature
controller to it. It still has the 2 "energy controllers" fitted, one
for each bank but they are normally set to max or off if one bank is not
needed.

The Vigor furnace is rated at 1.6 KW, being 14 amps at 115 volts.
However, the heater coils are old, and only draw 11 amps at 113 volts,
or 1.24 KW. At full power (with no voltage drop in the controller),
after closing up a bunch of heat leaks, it gets to 1000 degrees C.

If I understand, you electronically control only one of the two banks,
the other being on or off as needed, so the electronic controller
handles 2 KW at 220 volts.


I added a thermocouple to the kiln and connector into the box on the
side. The temperature controller is housed in a separate box with tails
out the back and mains plugs on the end so I can use it for controlling
other things if required, it also allows it to be placed away from the
heat. The thermocouple lead currently plugs into the front of the
controller box.

I thought of having a separate box, but all-in-one is more convenient,
and the commercial furnaces have the same scheme that I used, thermal
isolation using a set of parallel plates and spacers, so I knew it would
work.


The finned heat sink is about 3"H x 3"W x 1.2"D and gets
warm to the touch when running max duty, like when firing to 1200C, but
very acceptable.

Operation at 220 volts cuts the current in half. A solid-state relay
(SSR) has a constant voltage drop, being 1.2 volts for the SSR I'm
using, so half the current is half the power to be dissipated in the
heatsink. This (and the distance from the furnace and its heat)
explains the difference in needed heatsink size.


One of these days I'll add a temperature controller I have to my small
Gallenkamp heat treatment furnace as the energy controller on that is a
pain, but the thermocouple read-out is accurate from checks I've done.

For the record, the old thermocouple that came with the Vigor is made of
14 guage chromel-alumel (Type K), appears to be original from 1979, and
reads about 5 degrees C low. It's still perfectly useable.

Joe Gwinn

Joseph Gwinn wrote:
In article ,
David Billington wrote:


Joseph Gwinn wrote:

In early June 2008 I bought an old Vigor Burnout Furnace (model CA 1065)
for $95 from a seller on Craigslist. The furnace appears to have been
built in 1979, but does work.


[snip]

So I bought a 1/32 DIN PID controller and solid-state relay (SSR) from
Omega Engineering. I'm still using the thermocouple that came with the
furnace, but not for long, as the original thermocouple is old and
oxidized and a bit off. But it works well enough for now, and will hold
to within a degree or so of a temperature, far better than is required
in heat treating of say O1 oil hardening steel or A2 air hardening steel.

The big problem was that the original design didn't have a big enough
heatsink on the SSR, and there wasn't enough thermal isolation between
the control box and the furnace box, so the controller and SSR both got
too hot when the furnace went to max temperature (about 990 degrees C).
The controller would get to 50 degrees C, which is right at its upper
temperature limit, which is asking for reliability problems. The SSR
would get almost to 60 degrees C, which is also in its range, but asking
for trouble.

So, for the SSR I got a large heatsink from Omega, which dropped the
temperature to 36 degrees C.


[snip]

At this point, I have declared victory, as 35 or 36 degrees C is low
enough that reliability won't be much reduced.

Joe Gwinn


I've got an 18" 4kW top loading ceramic kiln that I use for heat
treatment and other things and I similarly fitted a temperature
controller to it. It still has the 2 "energy controllers" fitted, one
for each bank but they are normally set to max or off if one bank is not
needed.


The Vigor furnace is rated at 1.6 KW, being 14 amps at 115 volts.
However, the heater coils are old, and only draw 11 amps at 113 volts,
or 1.24 KW. At full power (with no voltage drop in the controller),
after closing up a bunch of heat leaks, it gets to 1000 degrees C.

If I understand, you electronically control only one of the two banks,
the other being on or off as needed, so the electronic controller
handles 2 KW at 220 volts.


The controller controls all input to the kiln but if I don't need 4kW
then I just switch off one of the elements as they are in parallel.


I added a thermocouple to the kiln and connector into the box on the
side. The temperature controller is housed in a separate box with tails
out the back and mains plugs on the end so I can use it for controlling
other things if required, it also allows it to be placed away from the
heat. The thermocouple lead currently plugs into the front of the
controller box.


I thought of having a separate box, but all-in-one is more convenient,
and the commercial furnaces have the same scheme that I used, thermal
isolation using a set of parallel plates and spacers, so I knew it would
work.

I have a glass melting furnace in the build stages and that will have
its own controller permanently attached for convenience, the current
controller was built as a seperate unit so I can use it to control other
items if required.



The finned heat sink is about 3"H x 3"W x 1.2"D and gets
warm to the touch when running max duty, like when firing to 1200C, but
very acceptable.


Operation at 220 volts cuts the current in half. A solid-state relay
(SSR) has a constant voltage drop, being 1.2 volts for the SSR I'm
using, so half the current is half the power to be dissipated in the
heatsink. This (and the distance from the furnace and its heat)
explains the difference in needed heatsink size.



Good point, I had failed to mention that I was running on 230V, the UK
standard mains voltage. I didn't occur to me that you were running yours
on 115V.

One of these days I'll add a temperature controller I have to my small
Gallenkamp heat treatment furnace as the energy controller on that is a
pain, but the thermocouple read-out is accurate from checks I've done.


For the record, the old thermocouple that came with the Vigor is made of
14 guage chromel-alumel (Type K), appears to be original from 1979, and
reads about 5 degrees C low. It's still perfectly useable.

Joe Gwinn

On 2008-08-13, Joseph Gwinn wrote:
In early June 2008 I bought an old Vigor Burnout Furnace (model CA 1065)
for $95 from a seller on Craigslist. The furnace appears to have been
built in 1979, but does work.

O.K. I picked up a small one at a tool flea market at a
collector's gathering. The heated area was about 4" wide, by 3" high,
by about 6" deep, with a counterbalanced raising door with a mica window
for viewing the interior when hot.

But it came with *no* controller.

IIRC, I think that it cost me something like $25.00 a few years
ago.

The furnace came with a so-called "infinite" control, which is an
electromechanical contraption with ten intensity settings (from mostly
off to always on). What varies is the average duty cycle of power on
versus power off. There is no feedback control. This is far too crude
and clumsy to heat-treat metals, so I decided to add an electronic
furnace controller.

Since I already had one of the Omega controllers and a stainless
steel enclosed thermocouple, all I had to do was to make a housing for
the controller and the SSR (a 20A 240V one which I also already had).
While I was at it, I added a locking miniature toggle switch (the kind
where you pull the handle to enable switching) between the output of the
controller and the input of the SSR, so I could use the controller to
track the cooldown temperature without having to reset it to cool down.

The oven was on legs about as tall as the aluminum box which I
selected for the housing, so I put that box on standoffs on the
right-hand side legs to minimize conducted heat from them (and not much
heat there anyway).

The box was sufficient heat sink for the 20A SSR, since I could
expect no more than 15A load from the wall anyway. I did use white heat
sink goop when I mounted it to the chassis, of course.

So I bought a 1/32 DIN PID controller and solid-state relay (SSR) from
Omega Engineering. I'm still using the thermocouple that came with the
furnace, but not for long, as the original thermocouple is old and
oxidized and a bit off. But it works well enough for now, and will hold
to within a degree or so of a temperature, far better than is required
in heat treating of say O1 oil hardening steel or A2 air hardening steel.

The big problem was that the original design didn't have a big enough
heatsink on the SSR, and there wasn't enough thermal isolation between
the control box and the furnace box, so the controller and SSR both got
too hot when the furnace went to max temperature (about 990 degrees C).
The controller would get to 50 degrees C, which is right at its upper
temperature limit, which is asking for reliability problems. The SSR
would get almost to 60 degrees C, which is also in its range, but asking
for trouble.

So, for the SSR I got a large heatsink from Omega, which dropped the
temperature to 36 degrees C.

The controller was a bit more difficult. I ended up making a set of
spacers from 0.5" diameter gummy aluminum rod on the lathe, and cutting
two aluminum plates with clearance holes, all to space the control box
away from the body of the furnace, with two parallel plates between,
thermally isolating control box from furnace body. Now, the PID
controller temperature is 35 degrees C max.

No tall legs on yours, I presume? Overall, it sounds like a
Blue-M muffle furnace which I had a work with the same duty-cycle type
controller. That one had the controller in a box to the right as part
of the overall oven housing. It did have a heavy-duty thermocouple
connected to an analog meter for readouts of the temperature.

No doubt this has long since gone to a surplus sale. :-)

At this point, I have declared victory, as 35 or 36 degrees C is low
enough that reliability won't be much reduced.

Agreed. I was quite amazed at the Omega controller. About two
thirds of the way up to set-point it shut off and measured the coast of
the heat on up, so when it reached near the set-point it had a total
overshoot of 1 degree F.

I got the controller for half price from someone in this
newsgroup in advance of need -- just knowing that I would eventually
need it. As it turns out, I was right. :-) Same for the SSRs -- I tend
to stock a few for future needs.

I've so far taken mine up to 1850F (1010C) and that took about
an hour, so I don't expect it to get much hotter. :-)

Enjoy,
DoN.

--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

In article ,
"DoN. Nichols" wrote:

On 2008-08-13, Joseph Gwinn wrote:
In early June 2008 I bought an old Vigor Burnout Furnace (model CA 1065)
for $95 from a seller on Craigslist. The furnace appears to have been
built in 1979, but does work.

O.K. I picked up a small one at a tool flea market at a
collector's gathering. The heated area was about 4" wide, by 3" high,
by about 6" deep, with a counterbalanced raising door with a mica window
for viewing the interior when hot.

On my Vigor, the heater volume is 13" wide by 6.5" high by 7" deep. The
door swings to one side on vertical-axis hinges.

Hmm. 4*3*6= 72 cubic inches, versus 13*6.5*7= 591.5 cubic inches, a
volume ratio of 8.2 to one. Did you get a burnout furnace, or a melter?


But it came with *no* controller.

I have a Robertshaw "infinite" controller for sale cheap...


IIRC, I think that it cost me something like $25.00 a few years
ago.

The furnace came with a so-called "infinite" control, which is an
electromechanical contraption with ten intensity settings (from mostly
off to always on). What varies is the average duty cycle of power on
versus power off. There is no feedback control. This is far too crude
and clumsy to heat-treat metals, so I decided to add an electronic
furnace controller.

Since I already had one of the Omega controllers and a stainless
steel enclosed thermocouple, all I had to do was to make a housing for
the controller and the SSR (a 20A 240V one which I also already had).
While I was at it, I added a locking miniature toggle switch (the kind
where you pull the handle to enable switching) between the output of the
controller and the input of the SSR, so I could use the controller to
track the cooldown temperature without having to reset it to cool down.

OK. I didn't do that.


The oven was on legs about as tall as the aluminum box which I
selected for the housing, so I put that box on standoffs on the
right-hand side legs to minimize conducted heat from them (and not much
heat there anyway).

The box was sufficient heat sink for the 20A SSR, since I could
expect no more than 15A load from the wall anyway. I did use white heat
sink goop when I mounted it to the chassis, of course.

This would *not* work on my furnace - the box is steel (poor heat
conductor) and itself gets quite warm at max temperature.


So I bought a 1/32 DIN PID controller and solid-state relay (SSR) from
Omega Engineering. I'm still using the thermocouple that came with the
furnace, but not for long, as the original thermocouple is old and
oxidized and a bit off. But it works well enough for now, and will hold
to within a degree or so of a temperature, far better than is required
in heat treating of say O1 oil hardening steel or A2 air hardening steel.

The big problem was that the original design didn't have a big enough
heatsink on the SSR, and there wasn't enough thermal isolation between
the control box and the furnace box, so the controller and SSR both got
too hot when the furnace went to max temperature (about 990 degrees C).
The controller would get to 50 degrees C, which is right at its upper
temperature limit, which is asking for reliability problems. The SSR
would get almost to 60 degrees C, which is also in its range, but asking
for trouble.

So, for the SSR I got a large heatsink from Omega, which dropped the
temperature to 36 degrees C.

The controller was a bit more difficult. I ended up making a set of
spacers from 0.5" diameter gummy aluminum rod on the lathe, and cutting
two aluminum plates with clearance holes, all to space the control box
away from the body of the furnace, with two parallel plates between,
thermally isolating control box from furnace body. Now, the PID
controller temperature is 35 degrees C max.

No tall legs on yours, I presume?

None whatsoever. There is a ventilated skirt which is an extension of
the vertical walls of the furnace. I have it setting on a wood bench,
which does not get all that warm.


Overall, it sounds like a
Blue-M muffle furnace which I had a work with the same duty-cycle type
controller. That one had the controller in a box to the right as part
of the overall oven housing. It did have a heavy-duty thermocouple
connected to an analog meter for readouts of the temperature.

No doubt this has long since gone to a surplus sale. :-)

Sounds like the Vigor for sure.


At this point, I have declared victory, as 35 or 36 degrees C is low
enough that reliability won't be much reduced.

Agreed. I was quite amazed at the Omega controller. About two
thirds of the way up to set-point it shut off and measured the coast of
the heat on up, so when it reached near the set-point it had a total
overshoot of 1 degree F.

That's a self-tuning PID (Proportional Integral Derivative) controller
for you. These used to be expensive, top-drawer industrial controls,
and now they are jellybeans. Mine cost $99 new.


I got the controller for half price from someone in this
newsgroup in advance of need -- just knowing that I would eventually
need it. As it turns out, I was right. :-) Same for the SSRs -- I tend
to stock a few for future needs.

I've so far taken mine up to 1850F (1010C) and that took about
an hour, so I don't expect it to get much hotter. :-)

I don't think my Vigor will get quite that hot at present, although if I
do some more repairs it probably will manage. One fine day the heater
element will fail, and they are still available for about $60, long
after Vigor went bust. Vigor must have sold a lot of these furnaces.

Joe Gwinn

In article ,
David Billington wrote:

Joseph Gwinn wrote:
In article ,
David Billington wrote:


Joseph Gwinn wrote:

In early June 2008 I bought an old Vigor Burnout Furnace (model CA 1065)
for $95 from a seller on Craigslist. The furnace appears to have been
built in 1979, but does work.


[snip]

So I bought a 1/32 DIN PID controller and solid-state relay (SSR) from
Omega Engineering. I'm still using the thermocouple that came with the
furnace, but not for long, as the original thermocouple is old and
oxidized and a bit off. But it works well enough for now, and will hold
to within a degree or so of a temperature, far better than is required
in heat treating of say O1 oil hardening steel or A2 air hardening steel.

The big problem was that the original design didn't have a big enough
heatsink on the SSR, and there wasn't enough thermal isolation between
the control box and the furnace box, so the controller and SSR both got
too hot when the furnace went to max temperature (about 990 degrees C).
The controller would get to 50 degrees C, which is right at its upper
temperature limit, which is asking for reliability problems. The SSR
would get almost to 60 degrees C, which is also in its range, but asking
for trouble.

So, for the SSR I got a large heatsink from Omega, which dropped the
temperature to 36 degrees C.


[snip]

At this point, I have declared victory, as 35 or 36 degrees C is low
enough that reliability won't be much reduced.

Joe Gwinn


I've got an 18" 4kW top loading ceramic kiln that I use for heat
treatment and other things and I similarly fitted a temperature
controller to it. It still has the 2 "energy controllers" fitted, one
for each bank but they are normally set to max or off if one bank is not
needed.


The Vigor furnace is rated at 1.6 KW, being 14 amps at 115 volts.
However, the heater coils are old, and only draw 11 amps at 113 volts,
or 1.24 KW. At full power (with no voltage drop in the controller),
after closing up a bunch of heat leaks, it gets to 1000 degrees C.

If I understand, you electronically control only one of the two banks,
the other being on or off as needed, so the electronic controller
handles 2 KW at 220 volts.

The controller controls all input to the kiln but if I don't need 4kW
then I just switch off one of the elements as they are in parallel.

OK. But this switching off is manual?


I added a thermocouple to the kiln and connector into the box on the
side. The temperature controller is housed in a separate box with tails
out the back and mains plugs on the end so I can use it for controlling
other things if required, it also allows it to be placed away from the
heat. The thermocouple lead currently plugs into the front of the
controller box.

I thought of having a separate box, but all-in-one is more convenient,
and the commercial furnaces have the same scheme that I used, thermal
isolation using a set of parallel plates and spacers, so I knew it would
work.

I have a glass melting furnace in the build stages and that will have
its own controller permanently attached for convenience, the current
controller was built as a seperate unit so I can use it to control other
items if required.

What temperature does this require?


The finned heat sink is about 3"H x 3"W x 1.2"D and gets
warm to the touch when running max duty, like when firing to 1200C, but
very acceptable.


Operation at 220 volts cuts the current in half. A solid-state relay
(SSR) has a constant voltage drop, being 1.2 volts for the SSR I'm
using, so half the current is half the power to be dissipated in the
heatsink. This (and the distance from the furnace and its heat)
explains the difference in needed heatsink size.

Good point, I had failed to mention that I was running on 230V, the UK
standard mains voltage. I didn't occur to me that you were running yours
on 115V.

Yes, but we Yanks know where you live...

Joe Gwinn


One of these days I'll add a temperature controller I have to my small
Gallenkamp heat treatment furnace as the energy controller on that is a
pain, but the thermocouple read-out is accurate from checks I've done.


For the record, the old thermocouple that came with the Vigor is made of
14 guage chromel-alumel (Type K), appears to be original from 1979, and
reads about 5 degrees C low. It's still perfectly useable.

Joe Gwinn

Joseph Gwinn wrote:

[snip]
The Vigor furnace is rated at 1.6 KW, being 14 amps at 115 volts.
However, the heater coils are old, and only draw 11 amps at 113 volts,
or 1.24 KW. At full power (with no voltage drop in the controller),
after closing up a bunch of heat leaks, it gets to 1000 degrees C.

If I understand, you electronically control only one of the two banks,
the other being on or off as needed, so the electronic controller
handles 2 KW at 220 volts.

The controller controls all input to the kiln but if I don't need 4kW
then I just switch off one of the elements as they are in parallel.


OK. But this switching off is manual?



Yes, the energy controllers fitted to the kiln have an off position and
a full on position on the knob as well as settings in between.

I added a thermocouple to the kiln and connector into the box on the
side. The temperature controller is housed in a separate box with tails
out the back and mains plugs on the end so I can use it for controlling
other things if required, it also allows it to be placed away from the
heat. The thermocouple lead currently plugs into the front of the
controller box.

I thought of having a separate box, but all-in-one is more convenient,
and the commercial furnaces have the same scheme that I used, thermal
isolation using a set of parallel plates and spacers, so I knew it would
work.


I have a glass melting furnace in the build stages and that will have
its own controller permanently attached for convenience, the current
controller was built as a seperate unit so I can use it to control other
items if required.


What temperature does this require?

Depends on the glass but I intend to use one that would normally be
gathered at about 1100C, maximum intended glass temperature is 1250C and
element temperature will be a bit higher. Maximum for the likes of
Kanthal A1 is 1350C IIRC so pushing the upper limit but as I am
intending to be a glassblowing weekend warrior it's a workable and cheap
option compared to the likes of SiC or MoSi2 elements.



The finned heat sink is about 3"H x 3"W x 1.2"D and gets
warm to the touch when running max duty, like when firing to 1200C, but
very acceptable.


Operation at 220 volts cuts the current in half. A solid-state relay
(SSR) has a constant voltage drop, being 1.2 volts for the SSR I'm
using, so half the current is half the power to be dissipated in the
heatsink. This (and the distance from the furnace and its heat)
explains the difference in needed heatsink size.


Good point, I had failed to mention that I was running on 230V, the UK
standard mains voltage. I didn't occur to me that you were running yours
on 115V.


Yes, but we Yanks know where you live...

Joe Gwinn



One of these days I'll add a temperature controller I have to my small
Gallenkamp heat treatment furnace as the energy controller on that is a
pain, but the thermocouple read-out is accurate from checks I've done.


For the record, the old thermocouple that came with the Vigor is made of
14 guage chromel-alumel (Type K), appears to be original from 1979, and
reads about 5 degrees C low. It's still perfectly useable.

Joe Gwinn

In article ,
David Billington wrote:

Joseph Gwinn wrote:

[snip]
The Vigor furnace is rated at 1.6 KW, being 14 amps at 115 volts.
However, the heater coils are old, and only draw 11 amps at 113 volts,
or 1.24 KW. At full power (with no voltage drop in the controller),
after closing up a bunch of heat leaks, it gets to 1000 degrees C.

If I understand, you electronically control only one of the two banks,
the other being on or off as needed, so the electronic controller
handles 2 KW at 220 volts.

The controller controls all input to the kiln but if I don't need 4kW
then I just switch off one of the elements as they are in parallel.


OK. But this switching off is manual?



Yes, the energy controllers fitted to the kiln have an off position and
a full on position on the knob as well as settings in between.

OK.


I added a thermocouple to the kiln and connector into the box on the
side. The temperature controller is housed in a separate box with tails
out the back and mains plugs on the end so I can use it for controlling
other things if required, it also allows it to be placed away from the
heat. The thermocouple lead currently plugs into the front of the
controller box.

I thought of having a separate box, but all-in-one is more convenient,
and the commercial furnaces have the same scheme that I used, thermal
isolation using a set of parallel plates and spacers, so I knew it would
work.


I have a glass melting furnace in the build stages and that will have
its own controller permanently attached for convenience, the current
controller was built as a seperate unit so I can use it to control other
items if required.


What temperature does this require?

Depends on the glass but I intend to use one that would normally be
gathered at about 1100C, maximum intended glass temperature is 1250C and
element temperature will be a bit higher. Maximum for the likes of
Kanthal A1 is 1350C IIRC so pushing the upper limit but as I am
intending to be a glassblowing weekend warrior it's a workable and cheap
option compared to the likes of SiC or MoSi2 elements.

I won't be doing any glassblowing then. I think that my Vigor has
nichrome heaters, but I've never seen nichrome and Kanthal A1
side-by-side either.

Joe Gwinn

Joseph Gwinn wrote:

On 2008-08-13, Joseph Gwinn wrote:
In early June 2008 I bought an old Vigor Burnout Furnace (model CA 1065)
for $95 from a seller on Craigslist. The furnace appears to have been
built in 1979, but does work.


Joe Gwinn


Wow Joe, that was me you got that thing from. HA. I guess I should have
recognized you as an RCM'er, I've seen your posts here plenty of times.
In any event, glad that thing worked out for you. That was about what I
was planning on doing with it, converting to an Omega control. We use
loads of the Omega CN9000 series. Self tuning and very reliable.

I stumbled on a near looks like new Ney-Dental Vulcan box furnace, the
box is about 16" cube with a fancy-pants multi-step ramping digital
control. Good for 1100C, It was being disposed of because of a minor
electrical issue that was easily fixed, so I got it for a price I could
not refuse.

Glad that worked out for you joe. Pleasure to meet you!
-Al A.

On 2008-08-14, Joseph Gwinn wrote:
In article ,
"DoN. Nichols" wrote:

On 2008-08-13, Joseph Gwinn wrote:
In early June 2008 I bought an old Vigor Burnout Furnace (model CA 1065)
for $95 from a seller on Craigslist. The furnace appears to have been
built in 1979, but does work.

O.K. I picked up a small one at a tool flea market at a
collector's gathering. The heated area was about 4" wide, by 3" high,
by about 6" deep, with a counterbalanced raising door with a mica window
for viewing the interior when hot.

On my Vigor, the heater volume is 13" wide by 6.5" high by 7" deep. The
door swings to one side on vertical-axis hinges.

A lot more space.

Hmm. 4*3*6= 72 cubic inches, versus 13*6.5*7= 591.5 cubic inches, a
volume ratio of 8.2 to one. Did you get a burnout furnace, or a melter?

I have no idea. There were no labels -- manufacturer or model
number -- remaining on this one.

But there were no provisions for runoff of wax, and the
orientation is similar to a brick on its flat side, with the smallest
area towards the door.

If the original controller were still present I might have a
clue from the range it was intended to cover. But all there was was a
pair of stiff wires insulated in asbestos coming out the back to connect
to my controller. It works nicely for heat treating small workpieces at
least.


But it came with *no* controller.

I have a Robertshaw "infinite" controller for sale cheap...

No thank you. :-)

[ ... ]

Since I already had one of the Omega controllers and a stainless
steel enclosed thermocouple, all I had to do was to make a housing for
the controller and the SSR (a 20A 240V one which I also already had).
While I was at it, I added a locking miniature toggle switch (the kind
where you pull the handle to enable switching) between the output of the
controller and the input of the SSR, so I could use the controller to
track the cooldown temperature without having to reset it to cool down.

OK. I didn't do that.

An easy thing to add after the fact -- as long as you have some
extra front panel space available.

The oven was on legs about as tall as the aluminum box which I
selected for the housing, so I put that box on standoffs on the
right-hand side legs to minimize conducted heat from them (and not much
heat there anyway).

The box was sufficient heat sink for the 20A SSR, since I could
expect no more than 15A load from the wall anyway. I did use white heat
sink goop when I mounted it to the chassis, of course.

This would *not* work on my furnace - the box is steel (poor heat
conductor) and itself gets quite warm at max temperature.

O.K. Make an aluminum box to mount on the side, with standoffs
and perhaps an intermediate sheet of aluminum between two sets of
standoffs. Use the original controller box for storing accessories
which won't be harmed by the heat. :-)

[ ... ]

So, for the SSR I got a large heatsink from Omega, which dropped the
temperature to 36 degrees C.

The controller was a bit more difficult. I ended up making a set of
spacers from 0.5" diameter gummy aluminum rod on the lathe, and cutting
two aluminum plates with clearance holes, all to space the control box
away from the body of the furnace, with two parallel plates between,
thermally isolating control box from furnace body. Now, the PID
controller temperature is 35 degrees C max.

No tall legs on yours, I presume?

None whatsoever. There is a ventilated skirt which is an extension of
the vertical walls of the furnace. I have it setting on a wood bench,
which does not get all that warm.

O.K. How tall is the skirt? Not tall enough to use it as the
mounting point for the controller, I presume.

Overall, it sounds like a
Blue-M muffle furnace which I had a work with the same duty-cycle type
controller. That one had the controller in a box to the right as part
of the overall oven housing. It did have a heavy-duty thermocouple
connected to an analog meter for readouts of the temperature.

No doubt this has long since gone to a surplus sale. :-)

Sounds like the Vigor for sure.

Proably made by the same company -- whether that it Vigor or
Blue-M -- just for different markets. The Blue-M came from a lab supply
catalog.

At this point, I have declared victory, as 35 or 36 degrees C is low
enough that reliability won't be much reduced.

Agreed. I was quite amazed at the Omega controller. About two
thirds of the way up to set-point it shut off and measured the coast of
the heat on up, so when it reached near the set-point it had a total
overshoot of 1 degree F.

That's a self-tuning PID (Proportional Integral Derivative) controller
for you. These used to be expensive, top-drawer industrial controls,
and now they are jellybeans. Mine cost $99 new.

Hmm ... I think that they were $200.00 when I got mine, and
since I got mine at half price, I got it for the same that you did. :-)

There was someone on this newsgroup who had several left over
unused after a project closed down, and who was offering them here. I'm
glad that I got one. I wonder whether we even have the same model? It
would take me a bit of work to verify the model now. Mine has the
plug-in strip along the top which says that it is displaying in degrees
C, but I've switched mine over to display in degrees F, since that
matches the information in _Machinery's Handbook_ more closely.

I got the controller for half price from someone in this
newsgroup in advance of need -- just knowing that I would eventually
need it. As it turns out, I was right. :-) Same for the SSRs -- I tend
to stock a few for future needs.

I've so far taken mine up to 1850F (1010C) and that took about
an hour, so I don't expect it to get much hotter. :-)

I don't think my Vigor will get quite that hot at present, although if I
do some more repairs it probably will manage. One fine day the heater
element will fail, and they are still available for about $60, long
after Vigor went bust. Vigor must have sold a lot of these furnaces.

I did have to make a bushing to go around the thermocouple probe
to minimize airflow through it. The original hole was something like 1"
diameter -- way too much for the skinny probe which I had, so I turned
up a bushing of lava, and then cooked it in the oven itself (which turns
it from whiteish-gray as machined to pink. :-)

It may be time to do another one, with a larger hole for an
alternative thermocouple which I found out in /dev/barn/01 a couple of
weeks ago with an analog meter. That would give me a totally power-free
way to monitor the temperatures.

Good Luck,
DoN.

--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

In article ,
"DoN. Nichols" wrote:

On 2008-08-14, Joseph Gwinn wrote:
In article ,
"DoN. Nichols" wrote:

On 2008-08-13, Joseph Gwinn wrote:
In early June 2008 I bought an old Vigor Burnout Furnace (model CA 1065)
for $95 from a seller on Craigslist. The furnace appears to have been
built in 1979, but does work.

O.K. I picked up a small one at a tool flea market at a
collector's gathering. The heated area was about 4" wide, by 3" high,
by about 6" deep, with a counterbalanced raising door with a mica window
for viewing the interior when hot.

On my Vigor, the heater volume is 13" wide by 6.5" high by 7" deep. The
door swings to one side on vertical-axis hinges.

A lot more space.

Hmm. 4*3*6= 72 cubic inches, versus 13*6.5*7= 591.5 cubic inches, a
volume ratio of 8.2 to one. Did you get a burnout furnace, or a melter?

I have no idea. There were no labels -- manufacturer or model
number -- remaining on this one.

It could be either I suppose. I assume that one needs both kinds of
furnace, or the logistics of getting molten metal into glowing-hot mold
become intractible. Unless the melting is done with a torch and
crucible.


But there were no provisions for runoff of wax, and the
orientation is similar to a brick on its flat side, with the smallest
area towards the door.

There are no provisions for wax runoff in mine either. I don't think
they worry about the wax, and just let it burn off. I have read of
burnoff furnaces with a smoke vent, but I suppose that would only be for
large furnaces.


If the original controller were still present I might have a
clue from the range it was intended to cover. But all there was was a
pair of stiff wires insulated in asbestos coming out the back to connect
to my controller. It works nicely for heat treating small workpieces at
least.

Probably a 14 guage Type K (chromel-alumel) thermocouple.

Chromel and alumel are basically a form of stainless steel.


But it came with *no* controller.

I have a Robertshaw "infinite" controller for sale cheap...

No thank you. :-)

[ ... ]

Since I already had one of the Omega controllers and a stainless
steel enclosed thermocouple, all I had to do was to make a housing for
the controller and the SSR (a 20A 240V one which I also already had).
While I was at it, I added a locking miniature toggle switch (the kind
where you pull the handle to enable switching) between the output of the
controller and the input of the SSR, so I could use the controller to
track the cooldown temperature without having to reset it to cool down.

OK. I didn't do that.

An easy thing to add after the fact -- as long as you have some
extra front panel space available.

I made space by removing the original moving-coil pyrometer. The 1/32
DIN controller easily fits in the hole left by the pyrometer.

The pyrometer does seem to work, and I'll calibrate it and use it as a
backup for the fancy electronics. It may benefit from a new
thermocouple.


The oven was on legs about as tall as the aluminum box which I
selected for the housing, so I put that box on standoffs on the
right-hand side legs to minimize conducted heat from them (and not much
heat there anyway).

The box was sufficient heat sink for the 20A SSR, since I could
expect no more than 15A load from the wall anyway. I did use white heat
sink goop when I mounted it to the chassis, of course.

This would *not* work on my furnace - the box is steel (poor heat
conductor) and itself gets quite warm at max temperature.

O.K. Make an aluminum box to mount on the side, with standoffs
and perhaps an intermediate sheet of aluminum between two sets of
standoffs. Use the original controller box for storing accessories
which won't be harmed by the heat. :-)

That would certainly work, but would stick out very far to the right.

I took my mechanical inspiration from pictures of current furnaces with
digital controllers.


[ ... ]

So, for the SSR I got a large heatsink from Omega, which dropped the
temperature to 36 degrees C.

The controller was a bit more difficult. I ended up making a set of
spacers from 0.5" diameter gummy aluminum rod on the lathe, and cutting
two aluminum plates with clearance holes, all to space the control box
away from the body of the furnace, with two parallel plates between,
thermally isolating control box from furnace body. Now, the PID
controller temperature is 35 degrees C max.

No tall legs on yours, I presume?

None whatsoever. There is a ventilated skirt which is an extension of
the vertical walls of the furnace. I have it setting on a wood bench,
which does not get all that warm.

O.K. How tall is the skirt? Not tall enough to use it as the
mounting point for the controller, I presume.

About 2.5". One could mount the controller in the skirt, but it would
make using the controller quite awkward, as it would be so low, and
would expose it to damage from dropped hot objects.


Overall, it sounds like a
Blue-M muffle furnace which I had a work with the same duty-cycle type
controller. That one had the controller in a box to the right as part
of the overall oven housing. It did have a heavy-duty thermocouple
connected to an analog meter for readouts of the temperature.

No doubt this has long since gone to a surplus sale. :-)

Sounds like the Vigor for sure.

Proably made by the same company -- whether that it Vigor or
Blue-M -- just for different markets. The Blue-M came from a lab supply
catalog.

I think that this was an industry-standard design, made by everybody and
sold by the pound.


At this point, I have declared victory, as 35 or 36 degrees C is low
enough that reliability won't be much reduced.

Agreed. I was quite amazed at the Omega controller. About two
thirds of the way up to set-point it shut off and measured the coast of
the heat on up, so when it reached near the set-point it had a total
overshoot of 1 degree F.

That's a self-tuning PID (Proportional Integral Derivative) controller
for you. These used to be expensive, top-drawer industrial controls,
and now they are jellybeans. Mine cost $99 new.

Hmm ... I think that they were $200.00 when I got mine, and
since I got mine at half price, I got it for the same that you did. :-)

Yes. By the way, the self-tuning feature may benefit from some
training. Once or twice, instead of simply turning the power off when
done, set the setpoint temperature to a little above ambient, say 50 C,
and let the controller follow the temperature down, for the experience.


There was someone on this newsgroup who had several left over
unused after a project closed down, and who was offering them here. I'm
glad that I got one. I wonder whether we even have the same model? It
would take me a bit of work to verify the model now. Mine has the
plug-in strip along the top which says that it is displaying in degrees
C, but I've switched mine over to display in degrees F, since that
matches the information in _Machinery's Handbook_ more closely.

What I got is a Omega CN7523 controller driving a Omega SSR330DC SSR
which is mounted on an Omega FHS-7 heatsink.


I got the controller for half price from someone in this
newsgroup in advance of need -- just knowing that I would eventually
need it. As it turns out, I was right. :-) Same for the SSRs -- I tend
to stock a few for future needs.

I've so far taken mine up to 1850F (1010C) and that took about
an hour, so I don't expect it to get much hotter. :-)

I don't think my Vigor will get quite that hot at present, although if I
do some more repairs it probably will manage. One fine day the heater
element will fail, and they are still available for about $60, long
after Vigor went bust. Vigor must have sold a lot of these furnaces.

I did have to make a bushing to go around the thermocouple probe
to minimize airflow through it. The original hole was something like 1"
diameter -- way too much for the skinny probe which I had, so I turned
up a bushing of lava, and then cooked it in the oven itself (which turns
it from whiteish-gray as machined to pink. :-)

In my Vigor, the hole fits the ceramic sleeve insulating the
thermocouple reasonably tightly.

One can also make bushings from K23 foam firebrick and glue it into
place with furnace cement.

http://www.sheffield-pottery.com


It may be time to do another one, with a larger hole for an
alternative thermocouple which I found out in /dev/barn/01 a couple of
weeks ago with an analog meter. That would give me a totally power-free
way to monitor the temperatures.

The traditional moving-coil pyrometers are self-powered, and are
optimized to work with a thermocouple. They are accurate enough for
heat treating. Some pyrometers were designed for mounting in a steel
panel, and are inaccurate if not in the panel, so if the panel is
aluminum it may be necessary to provide a piece of sheet steel as well.


Joe

In article ,
"Al A." wrote:

Joseph Gwinn wrote:

On 2008-08-13, Joseph Gwinn wrote:
In early June 2008 I bought an old Vigor Burnout Furnace (model CA 1065)
for $95 from a seller on Craigslist. The furnace appears to have been
built in 1979, but does work.


Wow Joe, that was me you got that thing from. HA. I guess I should have
recognized you as an RCM'er, I've seen your posts here plenty of times.

Well, I'll be damned. Stands to reason, I suppose.


In any event, glad that thing worked out for you. That was about what I
was planning on doing with it, converting to an Omega control. We use
loads of the Omega CN9000 series. Self tuning and very reliable.

How about CN7500 series?


I stumbled on a near looks like new Ney-Dental Vulcan box furnace, the
box is about 16" cube with a fancy-pants multi-step ramping digital
control.

I looked at those fancy controllers, but it seemed like a lot of trouble
to program for one-off jobs.


Good for 1100C, It was being disposed of because of a minor
electrical issue that was easily fixed, so I got it for a price I could
not refuse.

Isn't that a RCM staple - stuff tossed for lack of a fuse - and the
knowledge to replace it.


Glad that worked out for you joe. Pleasure to meet you!

Thanks. Likewise.

Joe Gwinn

On 2008-08-15, Joseph Gwinn wrote:
In article ,
"DoN. Nichols" wrote:

On 2008-08-14, Joseph Gwinn wrote:
In article ,
"DoN. Nichols" wrote:

On 2008-08-13, Joseph Gwinn wrote:

[ ... ]

Hmm. 4*3*6= 72 cubic inches, versus 13*6.5*7= 591.5 cubic inches, a
volume ratio of 8.2 to one. Did you get a burnout furnace, or a melter?

I have no idea. There were no labels -- manufacturer or model
number -- remaining on this one.

It could be either I suppose. I assume that one needs both kinds of
furnace, or the logistics of getting molten metal into glowing-hot mold
become intractible. Unless the melting is done with a torch and
crucible.

Well ... I intend to use this purely for heat treating. It is
too small to handle a crucible of molten metal safely. You press down
on a counterweight on a lever to the left and the door lifts from in
front of the heat zone.

There is a shelf in front of it -- slate or perhaps asbestos
board. Too discolored with age to tell for sure. About 1/4" thick,
FWIW.

But there were no provisions for runoff of wax, and the
orientation is similar to a brick on its flat side, with the smallest
area towards the door.

There are no provisions for wax runoff in mine either. I don't think
they worry about the wax, and just let it burn off. I have read of
burnoff furnaces with a smoke vent, but I suppose that would only be for
large furnaces.

Hmm ... no vent here, unless the 1" hole in the back was
supposed to be one. But it is not fully at the top of the back.


If the original controller were still present I might have a
clue from the range it was intended to cover. But all there was was a
pair of stiff wires insulated in asbestos coming out the back to connect
to my controller. It works nicely for heat treating small workpieces at
least.

Probably a 14 guage Type K (chromel-alumel) thermocouple.

Nope -- it is the wiring to the heating element. *Nothing*
which came with it was for measuring the temperature -- other than
perhaps the 1" diameter mica window in the door with an optical
pyrometer. :-)

Chromel and alumel are basically a form of stainless steel.

O.K. I've got the alloy definitions in my old CRC _Handbook of
Chemistry and Physics_ (otherwise known as the "rubber tables". :-)

[ ... ]

While I was at it, I added a locking miniature toggle switch (the kind
where you pull the handle to enable switching) between the output of the
controller and the input of the SSR, so I could use the controller to
track the cooldown temperature without having to reset it to cool down.

OK. I didn't do that.

I also added a larger LED to watch the cycling of the heating
element.

An easy thing to add after the fact -- as long as you have some
extra front panel space available.

I made space by removing the original moving-coil pyrometer. The 1/32
DIN controller easily fits in the hole left by the pyrometer.

The pyrometer does seem to work, and I'll calibrate it and use it as a
backup for the fancy electronics. It may benefit from a new
thermocouple.

O.K.

The oven was on legs about as tall as the aluminum box which I
selected for the housing, so I put that box on standoffs on the
right-hand side legs to minimize conducted heat from them (and not much
heat there anyway).

The box was sufficient heat sink for the 20A SSR, since I could
expect no more than 15A load from the wall anyway. I did use white heat
sink goop when I mounted it to the chassis, of course.

This would *not* work on my furnace - the box is steel (poor heat
conductor) and itself gets quite warm at max temperature.

O.K. Make an aluminum box to mount on the side, with standoffs
and perhaps an intermediate sheet of aluminum between two sets of
standoffs. Use the original controller box for storing accessories
which won't be harmed by the heat. :-)

That would certainly work, but would stick out very far to the right.

O.K. Can you punch a couple of holes in the side and mount a
small computer fan in there to circulate air whenever it is running?
Perhaps add a thermostat to keep the fan running for as long as there is
significant heat coming through the wall?

I took my mechanical inspiration from pictures of current furnaces with
digital controllers.

O.K. I just went with available Bud Minibox chassis (I didn't
at that time have a shear large enough to accompany my 24" brake to make
my own.)



[ ... ]

So, for the SSR I got a large heatsink from Omega, which dropped the
temperature to 36 degrees C.

The controller was a bit more difficult. I ended up making a set of
spacers from 0.5" diameter gummy aluminum rod on the lathe, and cutting
two aluminum plates with clearance holes, all to space the control box
away from the body of the furnace, with two parallel plates between,
thermally isolating control box from furnace body. Now, the PID
controller temperature is 35 degrees C max.

No tall legs on yours, I presume?

None whatsoever. There is a ventilated skirt which is an extension of
the vertical walls of the furnace. I have it setting on a wood bench,
which does not get all that warm.

O.K. How tall is the skirt? Not tall enough to use it as the
mounting point for the controller, I presume.

About 2.5". One could mount the controller in the skirt, but it would
make using the controller quite awkward, as it would be so low, and
would expose it to damage from dropped hot objects.

O.K. A bad idea, then.


Overall, it sounds like a
Blue-M muffle furnace which I had a work with the same duty-cycle type
controller. That one had the controller in a box to the right as part
of the overall oven housing. It did have a heavy-duty thermocouple
connected to an analog meter for readouts of the temperature.

No doubt this has long since gone to a surplus sale. :-)

Sounds like the Vigor for sure.

Proably made by the same company -- whether that it Vigor or
Blue-M -- just for different markets. The Blue-M came from a lab supply
catalog.

I think that this was an industry-standard design, made by everybody and
sold by the pound.

[ ... ]

Agreed. I was quite amazed at the Omega controller. About two
thirds of the way up to set-point it shut off and measured the coast of
the heat on up, so when it reached near the set-point it had a total
overshoot of 1 degree F.

That's a self-tuning PID (Proportional Integral Derivative) controller
for you. These used to be expensive, top-drawer industrial controls,
and now they are jellybeans. Mine cost $99 new.

Hmm ... I think that they were $200.00 when I got mine, and
since I got mine at half price, I got it for the same that you did. :-)

Yes. By the way, the self-tuning feature may benefit from some
training. Once or twice, instead of simply turning the power off when
done, set the setpoint temperature to a little above ambient, say 50 C,
and let the controller follow the temperature down, for the experience.

O.K. A good idea.

There was someone on this newsgroup who had several left over
unused after a project closed down, and who was offering them here. I'm
glad that I got one. I wonder whether we even have the same model? It
would take me a bit of work to verify the model now. Mine has the
plug-in strip along the top which says that it is displaying in degrees
C, but I've switched mine over to display in degrees F, since that
matches the information in _Machinery's Handbook_ more closely.

What I got is a Omega CN7523 controller driving a Omega SSR330DC SSR
which is mounted on an Omega FHS-7 heatsink.

Mine is too hard to get to at night. Easier when I can open the
shop door -- as I intend it to be when I'm using the oven. And a good
fire extinguisher handy, too. :-)

[ ... ]

I did have to make a bushing to go around the thermocouple probe
to minimize airflow through it. The original hole was something like 1"
diameter -- way too much for the skinny probe which I had, so I turned
up a bushing of lava, and then cooked it in the oven itself (which turns
it from whiteish-gray as machined to pink. :-)

In my Vigor, the hole fits the ceramic sleeve insulating the
thermocouple reasonably tightly.

One can also make bushings from K23 foam firebrick and glue it into
place with furnace cement.

O.K. But I *had* the machinable lava. It machines quite easily
in the lathe (very dusty), and when it is fired it turns pink and *very*
hard.

[ ... ]

It may be time to do another one, with a larger hole for an
alternative thermocouple which I found out in /dev/barn/01 a couple of
weeks ago with an analog meter. That would give me a totally power-free
way to monitor the temperatures.

The traditional moving-coil pyrometers are self-powered, and are
optimized to work with a thermocouple. They are accurate enough for
heat treating. Some pyrometers were designed for mounting in a steel
panel, and are inaccurate if not in the panel, so if the panel is
aluminum it may be necessary to provide a piece of sheet steel as well.

Right -- the steel panel shunts off some of the magnetic field
which of course changes the sensitivity somewhat. IIRC, this was
originally mounted in a non-magnetic alloy of stainless, so there is no
problem there.

Enjoy,
DoN.

--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

In article ,
"DoN. Nichols" wrote:

On 2008-08-15, Joseph Gwinn wrote:
In article ,
"DoN. Nichols" wrote:

On 2008-08-14, Joseph Gwinn wrote:
In article ,
"DoN. Nichols" wrote:

On 2008-08-13, Joseph Gwinn wrote:

[ ... ]

Hmm. 4*3*6= 72 cubic inches, versus 13*6.5*7= 591.5 cubic inches, a
volume ratio of 8.2 to one. Did you get a burnout furnace, or a melter?

I have no idea. There were no labels -- manufacturer or model
number -- remaining on this one.

It could be either I suppose. I assume that one needs both kinds of
furnace, or the logistics of getting molten metal into glowing-hot mold
become intractible. Unless the melting is done with a torch and
crucible.

Well ... I intend to use this purely for heat treating. It is
too small to handle a crucible of molten metal safely. You press down
on a counterweight on a lever to the left and the door lifts from in
front of the heat zone.

There is a shelf in front of it -- slate or perhaps asbestos
board. Too discolored with age to tell for sure. About 1/4" thick,
FWIW.

Can't be slate at that temperature, so asbestos board is more likely.


But there were no provisions for runoff of wax, and the
orientation is similar to a brick on its flat side, with the smallest
area towards the door.

There are no provisions for wax runoff in mine either. I don't think
they worry about the wax, and just let it burn off. I have read of
burnoff furnaces with a smoke vent, but I suppose that would only be for
large furnaces.

Hmm ... no vent here, unless the 1" hole in the back was
supposed to be one. But it is not fully at the top of the back.

My Vigor has a 1" diameter vent hole in the top, with a little metal
cover that one swings to the side. I wondered what it was for.


If the original controller were still present I might have a
clue from the range it was intended to cover. But all there was was a
pair of stiff wires insulated in asbestos coming out the back to connect
to my controller. It works nicely for heat treating small workpieces at
least.

Probably a 14 guage Type K (chromel-alumel) thermocouple.

Nope -- it is the wiring to the heating element. *Nothing*
which came with it was for measuring the temperature -- other than
perhaps the 1" diameter mica window in the door with an optical
pyrometer. :-)

Ah.


Chromel and alumel are basically a form of stainless steel.

O.K. I've got the alloy definitions in my old CRC _Handbook of
Chemistry and Physics_ (otherwise known as the "rubber tables". :-)

The Omega.com website has lots of information as well. As does NIST.


[ ... ]

While I was at it, I added a locking miniature toggle switch (the kind
where you pull the handle to enable switching) between the output of
the
controller and the input of the SSR, so I could use the controller to
track the cooldown temperature without having to reset it to cool down.

OK. I didn't do that.

I also added a larger LED to watch the cycling of the heating
element.

The Vigor had a neon pilot connected across the heating element, and so
I left it as it was.


An easy thing to add after the fact -- as long as you have some
extra front panel space available.

I made space by removing the original moving-coil pyrometer. The 1/32
DIN controller easily fits in the hole left by the pyrometer.

The pyrometer does seem to work, and I'll calibrate it and use it as a
backup for the fancy electronics. It may benefit from a new
thermocouple.

O.K.

I think one can buy pyrometers on eBay and at ham swap meets. There are
now lots of Pyrometers on the dole, having been made redundant by
digital controllers.


The oven was on legs about as tall as the aluminum box which I
selected for the housing, so I put that box on standoffs on the
right-hand side legs to minimize conducted heat from them (and not much
heat there anyway).

The box was sufficient heat sink for the 20A SSR, since I could
expect no more than 15A load from the wall anyway. I did use white
heat
sink goop when I mounted it to the chassis, of course.

This would *not* work on my furnace - the box is steel (poor heat
conductor) and itself gets quite warm at max temperature.

O.K. Make an aluminum box to mount on the side, with standoffs
and perhaps an intermediate sheet of aluminum between two sets of
standoffs. Use the original controller box for storing accessories
which won't be harmed by the heat. :-)

That would certainly work, but would stick out very far to the right.

O.K. Can you punch a couple of holes in the side and mount a
small computer fan in there to circulate air whenever it is running?
Perhaps add a thermostat to keep the fan running for as long as there is
significant heat coming through the wall?

I thought of this, but couldn't find an 115 volt AC fans that were small
enough. I probably can run a 24 volt fan off the controller signal to
the SSR, but the fan would run only when the element was on. Perhaps
that's enough.


I took my mechanical inspiration from pictures of current furnaces with
digital controllers.

O.K. I just went with available Bud Minibox chassis (I didn't
at that time have a shear large enough to accompany my 24" brake to make
my own.)

Doesn't Bud (or Hammond) still make steel chassis? Just like in the
1950s?


[ ... ]


There was someone on this newsgroup who had several left over
unused after a project closed down, and who was offering them here. I'm
glad that I got one. I wonder whether we even have the same model? It
would take me a bit of work to verify the model now. Mine has the
plug-in strip along the top which says that it is displaying in degrees
C, but I've switched mine over to display in degrees F, since that
matches the information in _Machinery's Handbook_ more closely.

What I got is a Omega CN7523 controller driving a Omega SSR330DC SSR
which is mounted on an Omega FHS-7 heatsink.

Mine is too hard to get to at night. Easier when I can open the
shop door -- as I intend it to be when I'm using the oven. And a good
fire extinguisher handy, too. :-)

Yes about the fire issue. I don't run this furnace if I'm not present,
at least not until I have some experience with it. The first thing I
did with it was to measure temperature versus time under power, to see
how long it took and how hot it got. This caused some tightening-up
exercises, which allowed the peak temperature to climb a bit. I've had
it up to 1,000 C or so.


[ ... ]

I did have to make a bushing to go around the thermocouple probe
to minimize airflow through it. The original hole was something like 1"
diameter -- way too much for the skinny probe which I had, so I turned
up a bushing of lava, and then cooked it in the oven itself (which turns
it from whiteish-gray as machined to pink. :-)

In my Vigor, the hole fits the ceramic sleeve insulating the
thermocouple reasonably tightly.

One can also make bushings from K23 foam firebrick and glue it into
place with furnace cement.

O.K. But I *had* the machinable lava. It machines quite easily
in the lathe (very dusty), and when it is fired it turns pink and *very*
hard.

What make and model is this material? It may be useful.


[ ... ]

It may be time to do another one, with a larger hole for an
alternative thermocouple which I found out in /dev/barn/01 a couple of
weeks ago with an analog meter. That would give me a totally power-free
way to monitor the temperatures.

The traditional moving-coil pyrometers are self-powered, and are
optimized to work with a thermocouple. They are accurate enough for
heat treating. Some pyrometers were designed for mounting in a steel
panel, and are inaccurate if not in the panel, so if the panel is
aluminum it may be necessary to provide a piece of sheet steel as well.

Right -- the steel panel shunts off some of the magnetic field
which of course changes the sensitivity somewhat. IIRC, this was
originally mounted in a non-magnetic alloy of stainless, so there is no
problem there.

So, you must avoid the steel.

Omega sells the #14 Type K thermocouples for something like $20 each, so
I wasn't tempted to scrounge for one.

Joe Gwinn

On 2008-08-16, Joseph Gwinn wrote:
In article ,
"DoN. Nichols" wrote:

[ ... ]

There is a shelf in front of it -- slate or perhaps asbestos
board. Too discolored with age to tell for sure. About 1/4" thick,
FWIW.

Can't be slate at that temperature, so asbestos board is more likely.

Especially if I pull something out at full temperature and leave
it resting on the shelf.

[ ... ]

Hmm ... no vent here, unless the 1" hole in the back was
supposed to be one. But it is not fully at the top of the back.

My Vigor has a 1" diameter vent hole in the top, with a little metal
cover that one swings to the side. I wondered what it was for.

In the top makes more sense than in the back where mine is. So
I just use mine for poking in the thermocouple.

[ ... ]

Chromel and alumel are basically a form of stainless steel.

O.K. I've got the alloy definitions in my old CRC _Handbook of
Chemistry and Physics_ (otherwise known as the "rubber tables". :-)

The Omega.com website has lots of information as well. As does NIST.

And somewhere I have a ton of literature from Omega -- but I
haven't seen it for a while. :-)

[ ... ]

I also added a larger LED to watch the cycling of the heating
element.

The Vigor had a neon pilot connected across the heating element, and so
I left it as it was.

O.K. But neon pilots -- especially after they age quite a bit,
tend to flicker on their own. Of course, if you *really* need to know,
you use the tiny LED in the controller. :-)

[ ... ]

The pyrometer does seem to work, and I'll calibrate it and use it as a
backup for the fancy electronics. It may benefit from a new
thermocouple.

O.K.

I think one can buy pyrometers on eBay and at ham swap meets. There are
now lots of Pyrometers on the dole, having been made redundant by
digital controllers.

:-)

"On the dole" -- are you in the UK by any chance? Or from
there?

[ ... ]

That would certainly work, but would stick out very far to the right.

O.K. Can you punch a couple of holes in the side and mount a
small computer fan in there to circulate air whenever it is running?
Perhaps add a thermostat to keep the fan running for as long as there is
significant heat coming through the wall?

I thought of this, but couldn't find an 115 volt AC fans that were small
enough. I probably can run a 24 volt fan off the controller signal to
the SSR, but the fan would run only when the element was on. Perhaps
that's enough.

Hmm ... a tiny switching power supply from a hamfest to power
it?

I took my mechanical inspiration from pictures of current furnaces with
digital controllers.

O.K. I just went with available Bud Minibox chassis (I didn't
at that time have a shear large enough to accompany my 24" brake to make
my own.)

Doesn't Bud (or Hammond) still make steel chassis? Just like in the
1950s?

I don't know. I have seen only aluminum ones recently.


[ ... ]


There was someone on this newsgroup who had several left over
unused after a project closed down, and who was offering them here. I'm
glad that I got one. I wonder whether we even have the same model? It
would take me a bit of work to verify the model now. Mine has the
plug-in strip along the top which says that it is displaying in degrees
C, but I've switched mine over to display in degrees F, since that
matches the information in _Machinery's Handbook_ more closely.

What I got is a Omega CN7523 controller driving a Omega SSR330DC SSR
which is mounted on an Omega FHS-7 heatsink.

Mine is too hard to get to at night. Easier when I can open the
shop door -- as I intend it to be when I'm using the oven. And a good
fire extinguisher handy, too. :-)

O.K. It is still daylight now, and I just checked. It is the
Omega "CN9000A". (IIRC, there is more fine detail to the number on a
label inside the box.

Yes about the fire issue. I don't run this furnace if I'm not present,
at least not until I have some experience with it. The first thing I
did with it was to measure temperature versus time under power, to see
how long it took and how hot it got. This caused some tightening-up
exercises, which allowed the peak temperature to climb a bit. I've had
it up to 1,000 C or so.

O.K. The highest that I've had mine is 1850 F (1010 C).

[ ... ]

In my Vigor, the hole fits the ceramic sleeve insulating the
thermocouple reasonably tightly.

One can also make bushings from K23 foam firebrick and glue it into
place with furnace cement.

O.K. But I *had* the machinable lava. It machines quite easily
in the lathe (very dusty), and when it is fired it turns pink and *very*
hard.

What make and model is this material? It may be useful.

Well ... I just did a Google search for "machinable lava", and
the first hit is:

http://www.professionalplastics.com/LAVA

(they insist on JavaScript being enabled) which says (in part):


================================================== ====================
Machinable Alumina Silicate L911A (Lava) Machinable Alumina Silicate
L911A (Lava) Aluminum silicate is machinable in an unfired state and
used in applications up to 1000 F After firing, parts are as hard as
carbide & usable up to 2100 F Aluminum silicate has low thermal
expansion Aluminum silicate is low cost Aluminum silicate is available
in wide range of stock up to 12" in diameter.

Some applications include prototype hardware, insulators, bushings,
soldering fixtures, nozzles, welding tips or whatever you need.
================================================== ====================

This site http://www.technicalproductsinc.com/lava.htm seems
to have more details about how it should be fired, and I obviously did
not do it quite right. :-)

[ ... ]

The traditional moving-coil pyrometers are self-powered, and are
optimized to work with a thermocouple. They are accurate enough for
heat treating. Some pyrometers were designed for mounting in a steel
panel, and are inaccurate if not in the panel, so if the panel is
aluminum it may be necessary to provide a piece of sheet steel as well.

Right -- the steel panel shunts off some of the magnetic field
which of course changes the sensitivity somewhat. IIRC, this was
originally mounted in a non-magnetic alloy of stainless, so there is no
problem there.

So, you must avoid the steel.

Omega sells the #14 Type K thermocouples for something like $20 each, so
I wasn't tempted to scrounge for one.

Well ... I already had them, so I did not need to purchase any, yet.

Enjoy,
DoN.

--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

In article ,
"DoN. Nichols" wrote:

On 2008-08-16, Joseph Gwinn wrote:
In article ,
"DoN. Nichols" wrote:

[ ... ]


Chromel and alumel are basically a form of stainless steel.

O.K. I've got the alloy definitions in my old CRC _Handbook of
Chemistry and Physics_ (otherwise known as the "rubber tables". :-)

The Omega.com website has lots of information as well. As does NIST.

And somewhere I have a ton of literature from Omega -- but I
haven't seen it for a while. :-)

It's also on their website.


[ ... ]

I also added a larger LED to watch the cycling of the heating
element.

The Vigor had a neon pilot connected across the heating element, and so
I left it as it was.

O.K. But neon pilots -- especially after they age quite a bit,
tend to flicker on their own. Of course, if you *really* need to know,
you use the tiny LED in the controller. :-)

This neon does not flicker, although it seems to be original.


[ ... ]

The pyrometer does seem to work, and I'll calibrate it and use it as a
backup for the fancy electronics. It may benefit from a new
thermocouple.

O.K.

I think one can buy pyrometers on eBay and at ham swap meets. There are
now lots of Pyrometers on the dole, having been made redundant by
digital controllers.

:-)

"On the dole" -- are you in the UK by any chance? Or from
there?

Neither. But I like their turn of phrase.


[ ... ]

That would certainly work, but would stick out very far to the right.

O.K. Can you punch a couple of holes in the side and mount a
small computer fan in there to circulate air whenever it is running?
Perhaps add a thermostat to keep the fan running for as long as there is
significant heat coming through the wall?

I thought of this, but couldn't find an 115 volt AC fans that were small
enough. I probably can run a 24 volt fan off the controller signal to
the SSR, but the fan would run only when the element was on. Perhaps
that's enough.

Hmm ... a tiny switching power supply from a hamfest to power
it?

I suppose, but we'll see if it's needed.



[ ... ]


There was someone on this newsgroup who had several left over
unused after a project closed down, and who was offering them here. I'm
glad that I got one. I wonder whether we even have the same model? It
would take me a bit of work to verify the model now. Mine has the
plug-in strip along the top which says that it is displaying in degrees
C, but I've switched mine over to display in degrees F, since that
matches the information in _Machinery's Handbook_ more closely.

What I got is a Omega CN7523 controller driving a Omega SSR330DC SSR
which is mounted on an Omega FHS-7 heatsink.

Mine is too hard to get to at night. Easier when I can open the
shop door -- as I intend it to be when I'm using the oven. And a good
fire extinguisher handy, too. :-)

O.K. It is still daylight now, and I just checked. It is the
Omega "CN9000A". (IIRC, there is more fine detail to the number on a
label inside the box.

It's twice the size of the CN7500 series, but would nonetheless fit in
the Vigor where I mounted the CN7500. Aside from a larger and more
convenient front panel, and more control functions, the controllers seem
more or less equivalent.


[ ... ]

In my Vigor, the hole fits the ceramic sleeve insulating the
thermocouple reasonably tightly.

One can also make bushings from K23 foam firebrick and glue it into
place with furnace cement.

O.K. But I *had* the machinable lava. It machines quite easily
in the lathe (very dusty), and when it is fired it turns pink and *very*
hard.

What make and model is this material? It may be useful.

Well ... I just did a Google search for "machinable lava", and
the first hit is:

http://www.professionalplastics.com/LAVA

(they insist on JavaScript being enabled) which says (in part):

I googled too, and had many hits, but didn't know which one you had.


================================================== ====================
Machinable Alumina Silicate L911A (Lava) Machinable Alumina Silicate
L911A (Lava) Aluminum silicate is machinable in an unfired state and
used in applications up to 1000 F After firing, parts are as hard as
carbide & usable up to 2100 F Aluminum silicate has low thermal
expansion Aluminum silicate is low cost Aluminum silicate is available
in wide range of stock up to 12" in diameter.

Some applications include prototype hardware, insulators, bushings,
soldering fixtures, nozzles, welding tips or whatever you need.
================================================== ====================

This site http://www.technicalproductsinc.com/lava.htm seems
to have more details about how it should be fired, and I obviously did
not do it quite right. :-)

I'll look into this. I recall that MSC sells the stuff, but it's
expensive.


[ ... ]

The traditional moving-coil pyrometers are self-powered, and are
optimized to work with a thermocouple. They are accurate enough for
heat treating. Some pyrometers were designed for mounting in a steel
panel, and are inaccurate if not in the panel, so if the panel is
aluminum it may be necessary to provide a piece of sheet steel as well.

Right -- the steel panel shunts off some of the magnetic field
which of course changes the sensitivity somewhat. IIRC, this was
originally mounted in a non-magnetic alloy of stainless, so there is no
problem there.

So, you must avoid the steel.

Omega sells the #14 Type K thermocouples for something like $20 each, so
I wasn't tempted to scrounge for one.

Well ... I already had them, so I did not need to purchase any, yet.

I did purchase what will eventually replace what came with the furnace.

Joe Gwinn

On 2008-08-17, Joseph Gwinn wrote:
In article ,
"DoN. Nichols" wrote:

On 2008-08-16, Joseph Gwinn wrote:

[ ... ]

The Omega.com website has lots of information as well. As does NIST.

And somewhere I have a ton of literature from Omega -- but I
haven't seen it for a while. :-)

It's also on their website.

Of course -- but I don't actually *need* that information at
present, and I have lots of places to find it when I do.

[ ... ]

The Vigor had a neon pilot connected across the heating element, and so
I left it as it was.

O.K. But neon pilots -- especially after they age quite a bit,
tend to flicker on their own. Of course, if you *really* need to know,
you use the tiny LED in the controller. :-)

This neon does not flicker, although it seems to be original.

Amazing.

[ ... ]

I think one can buy pyrometers on eBay and at ham swap meets. There are
now lots of Pyrometers on the dole, having been made redundant by
digital controllers.

:-)

"On the dole" -- are you in the UK by any chance? Or from
there?

Neither. But I like their turn of phrase.

O.K. I can understand that.

[ ... ]

I thought of this, but couldn't find an 115 volt AC fans that were small
enough. I probably can run a 24 volt fan off the controller signal to
the SSR, but the fan would run only when the element was on. Perhaps
that's enough.

Hmm ... a tiny switching power supply from a hamfest to power
it?

I suppose, but we'll see if it's needed.

O.K. Perhaps just a 12V fan and a wall wart to power it? :-)

[ ... ]

Mine is too hard to get to at night. Easier when I can open the
shop door -- as I intend it to be when I'm using the oven. And a good
fire extinguisher handy, too. :-)

O.K. It is still daylight now, and I just checked. It is the
Omega "CN9000A". (IIRC, there is more fine detail to the number on a
label inside the box.

It's twice the size of the CN7500 series, but would nonetheless fit in
the Vigor where I mounted the CN7500. Aside from a larger and more
convenient front panel, and more control functions, the controllers seem
more or less equivalent.

O.K.

[ ... ]

O.K. But I *had* the machinable lava. It machines quite easily
in the lathe (very dusty), and when it is fired it turns pink and *very*
hard.

What make and model is this material? It may be useful.

Well ... I just did a Google search for "machinable lava", and
the first hit is:

http://www.professionalplastics.com/LAVA

(they insist on JavaScript being enabled) which says (in part):

I googled too, and had many hits, but didn't know which one you had.

machinable lava

was my search string.

================================================== ====================
Machinable Alumina Silicate L911A (Lava) Machinable Alumina Silicate
L911A (Lava) Aluminum silicate is machinable in an unfired state and
used in applications up to 1000 F After firing, parts are as hard as
carbide & usable up to 2100 F Aluminum silicate has low thermal
expansion Aluminum silicate is low cost Aluminum silicate is available
in wide range of stock up to 12" in diameter.

Some applications include prototype hardware, insulators, bushings,
soldering fixtures, nozzles, welding tips or whatever you need.
================================================== ====================

This site http://www.technicalproductsinc.com/lava.htm seems
to have more details about how it should be fired, and I obviously did
not do it quite right. :-)

I'll look into this. I recall that MSC sells the stuff, but it's
expensive.

It helps that I have some of it already. :-)

[ ... ]

Omega sells the #14 Type K thermocouples for something like $20 each, so
I wasn't tempted to scrounge for one.

Well ... I already had them, so I did not need to purchase any, yet.

I did purchase what will eventually replace what came with the furnace.

O.K. I already had some nice unused stainless steel clad type K
thermocouples -- still got a spare for when this one gets cooked to
death. :-)

Enjoy,
DoN.

--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

In article ,
"DoN. Nichols" wrote:

On 2008-08-17, Joseph Gwinn wrote:
In article ,
"DoN. Nichols" wrote:

On 2008-08-16, Joseph Gwinn wrote:

[ ... ]

The Vigor had a neon pilot connected across the heating element, and so
I left it as it was.

O.K. But neon pilots -- especially after they age quite a bit,
tend to flicker on their own. Of course, if you *really* need to know,
you use the tiny LED in the controller. :-)

This neon does not flicker, although it seems to be original.

Amazing.

I took a closer look. The neon pilot could have been replaced, as the
connection is by means of 0.25" tabs. One can still buy exactly these
pilot lamps, so it could have been replaced quite recently.


[ ... ]

I think one can buy pyrometers on eBay and at ham swap meets. There are
now lots of Pyrometers on the dole, having been made redundant by
digital controllers.

:-)

"On the dole" -- are you in the UK by any chance? Or from
there?

Neither. But I like their turn of phrase.

O.K. I can understand that.

Is Boston close enough?


[ ... ]

I thought of this, but couldn't find an 115 volt AC fans that were small
enough. I probably can run a 24 volt fan off the controller signal to
the SSR, but the fan would run only when the element was on. Perhaps
that's enough.

Hmm ... a tiny switching power supply from a hamfest to power
it?

I suppose, but we'll see if it's needed.

O.K. Perhaps just a 12V fan and a wall wart to power it? :-)

Seems clunky. Not clear that it needs a fan either.


[ ... ]

O.K. But I *had* the machinable lava. It machines quite easily
in the lathe (very dusty), and when it is fired it turns pink and *very*
hard.

What make and model is this material? It may be useful.

Well ... I just did a Google search for "machinable lava", and
the first hit is:

http://www.professionalplastics.com/LAVA

(they insist on JavaScript being enabled) which says (in part):

I googled too, and had many hits, but didn't know which one you had.

machinable lava

was my search string.

Same.


================================================== ====================
Machinable Alumina Silicate L911A (Lava) Machinable Alumina Silicate
L911A (Lava) Aluminum silicate is machinable in an unfired state and
used in applications up to 1000 F After firing, parts are as hard as
carbide & usable up to 2100 F Aluminum silicate has low thermal
expansion Aluminum silicate is low cost Aluminum silicate is available
in wide range of stock up to 12" in diameter.

Some applications include prototype hardware, insulators, bushings,
soldering fixtures, nozzles, welding tips or whatever you need.
================================================== ====================

This site http://www.technicalproductsinc.com/lava.htm seems
to have more details about how it should be fired, and I obviously did
not do it quite right. :-)

I'll look into this. I recall that MSC sells the stuff, but it's
expensive.

It helps that I have some of it already. :-)

Ahh.


[ ... ]

Omega sells the #14 Type K thermocouples for something like $20 each, so
I wasn't tempted to scrounge for one.

Well ... I already had them, so I did not need to purchase any, yet.

I did purchase what will eventually replace what came with the furnace.

O.K. I already had some nice unused stainless steel clad type K
thermocouples -- still got a spare for when this one gets cooked to
death. :-)

It won't be soon I'll wager.


Joe Gwinn

What color is the Neon - is it orange or red ?

Red means there is a trace element to help it keep going... a nuke particle.

Might be over driven - e.g. - more current than normal so the intensity
stays on longer.

Martin

Martin H. Eastburn
@ home at Lions' Lair with our computer lionslair at consolidated dot net
TSRA, Endowed; NRA LOH & Patron Member, Golden Eagle, Patriot's Medal.
NRA Second Amendment Task Force Charter Founder
IHMSA and NRA Metallic Silhouette maker & member.
http://lufkinced.com/


Joseph Gwinn wrote:
In article ,
"DoN. Nichols" wrote:

On 2008-08-17, Joseph Gwinn wrote:
In article ,
"DoN. Nichols" wrote:

On 2008-08-16, Joseph Gwinn wrote:
[ ... ]

The Vigor had a neon pilot connected across the heating element, and so
I left it as it was.
O.K. But neon pilots -- especially after they age quite a bit,
tend to flicker on their own. Of course, if you *really* need to know,
you use the tiny LED in the controller. :-)
This neon does not flicker, although it seems to be original.
Amazing.

I took a closer look. The neon pilot could have been replaced, as the
connection is by means of 0.25" tabs. One can still buy exactly these
pilot lamps, so it could have been replaced quite recently.


[ ... ]

I think one can buy pyrometers on eBay and at ham swap meets. There are
now lots of Pyrometers on the dole, having been made redundant by
digital controllers.
:-)

"On the dole" -- are you in the UK by any chance? Or from
there?
Neither. But I like their turn of phrase.
O.K. I can understand that.

Is Boston close enough?


[ ... ]

I thought of this, but couldn't find an 115 volt AC fans that were small
enough. I probably can run a 24 volt fan off the controller signal to
the SSR, but the fan would run only when the element was on. Perhaps
that's enough.
Hmm ... a tiny switching power supply from a hamfest to power
it?
I suppose, but we'll see if it's needed.
O.K. Perhaps just a 12V fan and a wall wart to power it? :-)

Seems clunky. Not clear that it needs a fan either.


[ ... ]

O.K. But I *had* the machinable lava. It machines quite easily
in the lathe (very dusty), and when it is fired it turns pink and *very*
hard.
What make and model is this material? It may be useful.
Well ... I just did a Google search for "machinable lava", and
the first hit is:

http://www.professionalplastics.com/LAVA

(they insist on JavaScript being enabled) which says (in part):
I googled too, and had many hits, but didn't know which one you had.
machinable lava

was my search string.

Same.


================================================== ====================
Machinable Alumina Silicate L911A (Lava) Machinable Alumina Silicate
L911A (Lava) Aluminum silicate is machinable in an unfired state and
used in applications up to 1000 F After firing, parts are as hard as
carbide & usable up to 2100 F Aluminum silicate has low thermal
expansion Aluminum silicate is low cost Aluminum silicate is available
in wide range of stock up to 12" in diameter.

Some applications include prototype hardware, insulators, bushings,
soldering fixtures, nozzles, welding tips or whatever you need.
================================================== ====================

This site http://www.technicalproductsinc.com/lava.htm seems
to have more details about how it should be fired, and I obviously did
not do it quite right. :-)
I'll look into this. I recall that MSC sells the stuff, but it's
expensive.
It helps that I have some of it already. :-)

Ahh.


[ ... ]

Omega sells the #14 Type K thermocouples for something like $20 each, so
I wasn't tempted to scrounge for one.
Well ... I already had them, so I did not need to purchase any, yet.
I did purchase what will eventually replace what came with the furnace.
O.K. I already had some nice unused stainless steel clad type K
thermocouples -- still got a spare for when this one gets cooked to
death. :-)

It won't be soon I'll wager.


Joe Gwinn


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On 2008-08-17, Joseph Gwinn wrote:
In article ,
"DoN. Nichols" wrote:

On 2008-08-17, Joseph Gwinn wrote:

[ ... ]

This neon does not flicker, although it seems to be original.

Amazing.

I took a closer look. The neon pilot could have been replaced, as the
connection is by means of 0.25" tabs. One can still buy exactly these
pilot lamps, so it could have been replaced quite recently.

O.K. Also, I think that if they are being run brighter, they
keep from flickering longer. I've got an old surge protector box with
rocker switches with Neon lamps and they have all given up by now. It
does not matter really in this case, but they are all dark, and
difficult to access and replace. :-)

[ ... ]

"On the dole" -- are you in the UK by any chance? Or from
there?

Neither. But I like their turn of phrase.

O.K. I can understand that.

Is Boston close enough?

If you're in the Irish part, sure. They would say that. :-)

[ ... ]

I thought of this, but couldn't find an 115 volt AC fans that were small
enough. I probably can run a 24 volt fan off the controller signal to
the SSR, but the fan would run only when the element was on. Perhaps
that's enough.

Hmm ... a tiny switching power supply from a hamfest to power
it?

I suppose, but we'll see if it's needed.

O.K. Perhaps just a 12V fan and a wall wart to power it? :-)

Seems clunky. Not clear that it needs a fan either.

O.K. I just hope that the lifetime of the controller is not
shortened.

While looking at it to see the model number of the controller, I
also checked out the spacers from the legs. It looks as though I have
something like 2-1/2" to 3" spacers -- which brings the left edge of the
controller housing in line with the right edge of the oven box.

[ ... ]

machinable lava

[ ... ]

I'll look into this. I recall that MSC sells the stuff, but it's
expensive.

It helps that I have some of it already. :-)

Ahh.

Yes -- that does make a difference, doesn't it? :-) From a shop
at work which was being closed up -- back when I still was working.

[ ... ]

I did purchase what will eventually replace what came with the furnace.

O.K. I already had some nice unused stainless steel clad type K
thermocouples -- still got a spare for when this one gets cooked to
death. :-)

It won't be soon I'll wager.

I hope not.

Enjoy,
DoN.

--
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--- Black Holes are where God is dividing by zero ---

In article ,
"Martin H. Eastburn" wrote:

What color is the Neon - is it orange or red ?

Red means there is a trace element to help it keep going... a nuke particle.

Hard to say because the lens is red plastic, and the assembly is glued
together.


Might be over driven - e.g. - more current than normal so the intensity
stays on longer.

I recall that the harder one drove a neon bulb, the faster it wore out.

Joe Gwinn

In article ,
"DoN. Nichols" wrote:

On 2008-08-17, Joseph Gwinn wrote:
In article ,
"DoN. Nichols" wrote:

On 2008-08-17, Joseph Gwinn wrote:

[ ... ]

This neon does not flicker, although it seems to be original.

Amazing.

I took a closer look. The neon pilot could have been replaced, as the
connection is by means of 0.25" tabs. One can still buy exactly these
pilot lamps, so it could have been replaced quite recently.

O.K. Also, I think that if they are being run brighter, they
keep from flickering longer. I've got an old surge protector box with
rocker switches with Neon lamps and they have all given up by now. It
does not matter really in this case, but they are all dark, and
difficult to access and replace. :-)

I think that the harder one drives a neon bulb, the sooner it wears out.
A neon will flicker if it doesn't have enough current to cause the
plasma sheath to fully cover the smaller electrode, but that's a
different problem.

The simpler explanation is that someone replaced the pilot light when
the original got annoying.


[ ... ]

"On the dole" -- are you in the UK by any chance? Or from
there?

Neither. But I like their turn of phrase.

O.K. I can understand that.

Is Boston close enough?

If you're in the Irish part, sure. They would say that. :-)

Well, the wife is Irish. Close enough?



[ ... ]

I thought of this, but couldn't find an 115 volt AC fans that were
small
enough. I probably can run a 24 volt fan off the controller signal
to
the SSR, but the fan would run only when the element was on. Perhaps
that's enough.

Hmm ... a tiny switching power supply from a hamfest to power
it?

I suppose, but we'll see if it's needed.

O.K. Perhaps just a 12V fan and a wall wart to power it? :-)

Seems clunky. Not clear that it needs a fan either.

O.K. I just hope that the lifetime of the controller is not
shortened.

That was my worry too. On my first attempt, the controller sat at just
under 50 degrees C, which meets the datasheet max temp spec (50C), but
is asking for trouble. After the fixup effort, the controller sits at
36 C, which is far more comfortable. This with no fan.


While looking at it to see the model number of the controller, I
also checked out the spacers from the legs. It looks as though I have
something like 2-1/2" to 3" spacers -- which brings the left edge of the
controller housing in line with the right edge of the oven box.

OK.


Joe Gwinn

On 2008-08-18, Martin H. Eastburn wrote:
What color is the Neon - is it orange or red ?

Which one? The one in Joe's furnace, or the ones in my
surge-protector/outlet-switch-box?

In the latter case, *all* of them are now dark, so I can't tell
for sure. Also, the switch rockers are orange plastic, so I probably
could not tell even if they were still glowing.

Red means there is a trace element to help it keep going... a nuke particle.

Interesting.

Might be over driven - e.g. - more current than normal so the intensity
stays on longer.

That was what I was suspecting. Some are set up to just be
minimal glow, while others are set up to be clearly visible even in a
bright room.

Enjoy,
DoN.

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--- Black Holes are where God is dividing by zero ---

On 2008-08-18, Joseph Gwinn wrote:
In article ,
"DoN. Nichols" wrote:

[ ... ]

O.K. Also, I think that if they are being run brighter, they
keep from flickering longer. I've got an old surge protector box with
rocker switches with Neon lamps and they have all given up by now. It
does not matter really in this case, but they are all dark, and
difficult to access and replace. :-)

I think that the harder one drives a neon bulb, the sooner it wears out.

Well ... the sooner the envelope will darken with deposited
electrode vapor. But I think that it keeps the actual light behind the
darkening pretty constant.

A neon will flicker if it doesn't have enough current to cause the
plasma sheath to fully cover the smaller electrode, but that's a
different problem.

And the required current seems to increase over time.

The simpler explanation is that someone replaced the pilot light when
the original got annoying.

Certainly possible -- especially if the pilot is easy to get to.


[ ... ]

"On the dole" -- are you in the UK by any chance? Or from
there?

Neither. But I like their turn of phrase.

O.K. I can understand that.

Is Boston close enough?

If you're in the Irish part, sure. They would say that. :-)

Well, the wife is Irish. Close enough?

That will do, I think. :-)

Mine is French-Canadian, so I don't have that excuse. :-)

[ ... ]

O.K. Perhaps just a 12V fan and a wall wart to power it? :-)

Seems clunky. Not clear that it needs a fan either.

O.K. I just hope that the lifetime of the controller is not
shortened.

That was my worry too. On my first attempt, the controller sat at just
under 50 degrees C, which meets the datasheet max temp spec (50C), but
is asking for trouble. After the fixup effort, the controller sits at
36 C, which is far more comfortable. This with no fan.

O.K. At that temperature, never mind. :-)

Enjoy,
DoN.

--
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(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

"DoN. Nichols" wrote:

On 2008-08-18, Martin H. Eastburn wrote:
What color is the Neon - is it orange or red ?

Which one? The one in Joe's furnace, or the ones in my
surge-protector/outlet-switch-box?

In the latter case, *all* of them are now dark, so I can't tell
for sure. Also, the switch rockers are orange plastic, so I probably
could not tell even if they were still glowing.

Red means there is a trace element to help it keep going... a nuke particle.

Interesting.


That is the difference between the NE2 and the NE2H versions. The
NE2H was made for higher current, and brightness but some cheapskates
use the standard version to save a few pennies while knowing it won't
last very long.



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In article ,
"DoN. Nichols" wrote:

On 2008-08-18, Joseph Gwinn wrote:
In article ,
"DoN. Nichols" wrote:

[ ... ]

O.K. Also, I think that if they are being run brighter, they
keep from flickering longer. I've got an old surge protector box with
rocker switches with Neon lamps and they have all given up by now. It
does not matter really in this case, but they are all dark, and
difficult to access and replace. :-)

I think that the harder one drives a neon bulb, the sooner it wears out.

Well ... the sooner the envelope will darken with deposited
electrode vapor. But I think that it keeps the actual light behind the
darkening pretty constant.

I recall reading a datasheet on how to use neon lamps, and that this
datasheet said the the voltage needed to maintain the glow (it's not an
arc) increased with increasing usage of the lamp.


A neon will flicker if it doesn't have enough current to cause the
plasma sheath to fully cover the smaller electrode, but that's a
different problem.

And the required current seems to increase over time.

The simpler explanation is that someone replaced the pilot light when
the original got annoying.

Certainly possible -- especially if the pilot is easy to get to.

I hereby invoke Occam's Razor.


[ ... ]

"On the dole" -- are you in the UK by any chance? Or from
there?

Neither. But I like their turn of phrase.

O.K. I can understand that.

Is Boston close enough?

If you're in the Irish part, sure. They would say that. :-)

Well, the wife is Irish. Close enough?

That will do, I think. :-)

Mine is French-Canadian, so I don't have that excuse. :-)

They must have a suitable phrase that can be translated.

My favorite is "My Wife, The Moon" in transliteration. My wife asserts
that this cannot be translated (versus transliterated), but I think that
the meaning is quite clear. The common root is lunacy and lunatic.


Joe Gwinn

On 2008-08-19, Joseph Gwinn wrote:
In article ,
"DoN. Nichols" wrote:

[ ... ]

Well ... the sooner the envelope will darken with deposited
electrode vapor. But I think that it keeps the actual light behind the
darkening pretty constant.

I recall reading a datasheet on how to use neon lamps, and that this
datasheet said the the voltage needed to maintain the glow (it's not an
arc) increased with increasing usage of the lamp.

I never said (or even thought) that it was an arc.

[ ... ]

The simpler explanation is that someone replaced the pilot light when
the original got annoying.

Certainly possible -- especially if the pilot is easy to get to.

I hereby invoke Occam's Razor.

Another invocation thereof would be that while the oven may be
fairly old, that it was not used very much, so the aging of the lamp has
been postponed. :-)

[ ... ]

If you're in the Irish part, sure. They would say that. :-)

Well, the wife is Irish. Close enough?

That will do, I think. :-)

Mine is French-Canadian, so I don't have that excuse. :-)

They must have a suitable phrase that can be translated.

My favorite is "My Wife, The Moon" in transliteration. My wife asserts
that this cannot be translated (versus transliterated), but I think that
the meaning is quite clear. The common root is lunacy and lunatic.

:-)

Enjoy,
DoN.

--
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--- Black Holes are where God is dividing by zero ---

In article ,
"DoN. Nichols" wrote:

On 2008-08-19, Joseph Gwinn wrote:
In article ,
"DoN. Nichols" wrote:

[ ... ]

The simpler explanation is that someone replaced the pilot light when
the original got annoying.

Certainly possible -- especially if the pilot is easy to get to.

I hereby invoke Occam's Razor.

Another invocation thereof would be that while the oven may be
fairly old, that it was not used very much, so the aging of the lamp has
been postponed. :-)

The rest of the furnace looks like it's seen some miles.


[ ... ]

If you're in the Irish part, sure. They would say that. :-)

Well, the wife is Irish. Close enough?

That will do, I think. :-)

Mine is French-Canadian, so I don't have that excuse. :-)

They must have a suitable phrase that can be translated.

My favorite is "My Wife, The Moon" in transliteration. My wife asserts
that this cannot be translated (versus transliterated), but I think that
the meaning is quite clear. The common root is lunacy and lunatic.

:-)

That wasn't her reaction. But it was worth it.

Joe Gwinn

On Nov 29, 2016, kristen fitzgerald wrote
(in wsgroups.com):

replying to Joseph Gwinn, kristen fitzgerald wrote:
Hello- Do you happen to have the instructions? I have a furnace but no
instructions and can't find them anywhere online!!!! : (

I checked my records, and I never did find the instructions either. Not that
it mattered - that furnace is pretty simple. And, I replaced the entire
controller anyway.

Joe Gwinn



For full context,
visithttp://www.polytechforum.com/metalwo...rnout-furnace-
adapted-to-heat-treating-138175-.htm.