Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work.

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  #1   Report Post  
Roger N
 
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Default Homebuilding High Temp Furnace.


I'm thinking of building a high temperature furnace/oven/kiln or whatever
you want to call it. Anyone have links to supplies such as insulating
castable refractories, fire brick, heating elements or Kanthal wire, etc?
.....Or links where others have made similar ovens?


If I'm thinking about this correctly, the temperature will max out when the
furnace looses as much heat as is put in it. In other words a small, well
insulated box should be capable of high temperatures without an enormous
amount of heating elements and electricity. I was thinking that 1000 watts
on 120V might be enough for a 6" X 6" X 18" box with 3" insulating fire
brick, if not, perhaps wrap the outside of the box with some high temp
fiberglass insulation.

I noticed some of the Super Kanthal element wires were capable of over 3000
degrees F, sounds like they could be useful for making a small crucible
furnace. Anyone casting iron in the home shop?



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David Billington
 
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Default Homebuilding High Temp Furnace.

Some good design info at www.kanthal.com . They can also supply but
you'll have to find their local branch. Their is an US company that
supplies lots of make of heating wire and in small quantities on the
web www.resistancewire.com . Never dealt with them just useful info. For
refractories goto a local pottery supplier for a start.

Roger N wrote:

I'm thinking of building a high temperature furnace/oven/kiln or whatever
you want to call it. Anyone have links to supplies such as insulating
castable refractories, fire brick, heating elements or Kanthal wire, etc?
....Or links where others have made similar ovens?


If I'm thinking about this correctly, the temperature will max out when the
furnace looses as much heat as is put in it. In other words a small, well
insulated box should be capable of high temperatures without an enormous
amount of heating elements and electricity. I was thinking that 1000 watts
on 120V might be enough for a 6" X 6" X 18" box with 3" insulating fire
brick, if not, perhaps wrap the outside of the box with some high temp
fiberglass insulation.

I noticed some of the Super Kanthal element wires were capable of over 3000
degrees F, sounds like they could be useful for making a small crucible
furnace. Anyone casting iron in the home shop?




  #3   Report Post  
Steve Worcester
 
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Default Homebuilding High Temp Furnace.

I am right there with you. I am looking for a budget heat treating furnace.
I am looking into something round, about two 1lb coffee cans high on the
inside, and haven't figured out the outside yet.
First step was to buy the Gingery book on building a furnace. Looking into
refractory material and what to use as a mold. The controls and Kanthal are
also available from http://www.budgetcastingsupply.com/ . Still need to get
a better pyrometer though.
Let me know what you decide, I would like to compare notes.

--
Steve Worcester
www.turningwood.com
Better Woodturning through Technology
(And a hell of alotta practice)



"Roger N" wrote in message
k.net...

I'm thinking of building a high temperature furnace/oven/kiln or whatever
you want to call it. Anyone have links to supplies such as insulating
castable refractories, fire brick, heating elements or Kanthal wire, etc?
....Or links where others have made similar ovens?


If I'm thinking about this correctly, the temperature will max out when

the
furnace looses as much heat as is put in it. In other words a small, well
insulated box should be capable of high temperatures without an enormous
amount of heating elements and electricity. I was thinking that 1000

watts
on 120V might be enough for a 6" X 6" X 18" box with 3" insulating fire
brick, if not, perhaps wrap the outside of the box with some high temp
fiberglass insulation.

I noticed some of the Super Kanthal element wires were capable of over

3000
degrees F, sounds like they could be useful for making a small crucible
furnace. Anyone casting iron in the home shop?





  #4   Report Post  
Gary Brady
 
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Default Homebuilding High Temp Furnace.

I'm thinking of building a high temperature furnace/oven/kiln or whatever you
want to call it. Anyone have links to supplies such as insulating castable
refractories, fire brick, heating elements or Kanthal wire, etc?

Refractory: A.P. Green now sold through Harbison Walker Refractories
www.hwr.com

Kanthal wi http://www.duralite.com/


Gary Brady
Austin, TX
  #5   Report Post  
Glenn Cramond
 
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Default Homebuilding High Temp Furnace.

"Roger N" wrote in message nk.net...
I'm thinking of building a high temperature furnace/oven/kiln or whatever
you want to call it. Anyone have links to supplies such as insulating
castable refractories, fire brick, heating elements or Kanthal wire, etc?
....Or links where others have made similar ovens?

Try www.ray-vin.com/castings/furnace/furnace.shtml
www.reil1.net//design1.shtm
www.freemansupplyco.com/video.htm
http://groups.yahoo.com/group/castinghobby/

Glenn


  #6   Report Post  
James Waldby
 
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Default Homebuilding High Temp Furnace.

Steve Worcester wrote:
I am right there with you. I am looking for a budget heat treating furnace.
I am looking into something round, about two 1lb coffee cans high on the
inside, and haven't figured out the outside yet.
First step was to buy the Gingery book on building a furnace. Looking into
refractory material and what to use as a mold. The controls and Kanthal are
also available from http://www.budgetcastingsupply.com/ . Still need to get
a better pyrometer though.

....

Hi-Cast castable refractory like the following is stocked at some
brick stores: http://www.alsey.com/hicast_casable_industrial.htm
I paid about $13.50 per 50# bag. You add about 10%-by-weight
water, mix well, cast or mold or sculpture it, air-dry overnight,
cook at 250 F for a few hours to dry further and avoid steam
explosions, then cook at kiln temperature to develop strength.
-jiw
  #7   Report Post  
Dan Caster
 
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Default Homebuilding High Temp Furnace.

Seattle Pottery sell all the stuff you need including Kanthal wire and elements.
Dan


"Roger N" wrote in message news:M%60b.198 Anyone have links to supplies such as insulating
castable refractories, fire brick, heating elements or Kanthal wire, etc?
....Or links where others have made similar ovens?


  #8   Report Post  
Tom Boston
 
Posts: n/a
Default Homebuilding High Temp Furnace.

For the refractory casting, local pottery supply
shops, check yellow pages.

I'm sort of following the Gingery route, but
chose a discarded water heating tank for the
container. Search the yellow pages for repair
shops for water heating tanks, they usually
have old ones laying around the back of the
shop for recycling.

If possible, get an electric heater, the
gas ones have a metal tube in the middle of
them that are a PITA to deal with. I used
a hacksaw to cut it, and welded the bottom
shut afterwards.

Tom. (Boston)
  #9   Report Post  
RogerN
 
Posts: n/a
Default Homebuilding High Temp Furnace.


"Steve Worcester" wrote in message
...
Still need to get
a better pyrometer though.
Let me know what you decide, I would like to compare notes.


I bought an electronic temperature controller from eBay for under $50. It
is compatible with many different thermocouples and RTD's. I figured it was
a cost effective digital pyrometer with temperature control capabilities if
I choose to use them.

I have microcontroller programming equipment & compilers. I have been
thinking about programming a microcontroller to use as a temperature control
for heat treating. You could select pre-programmed heating profiles for
hardening & tempering different steels plus annealing cycles. A second
lower temp chamber would be desirable for tempering, might as well go first
class :-)



  #10   Report Post  
RogerN
 
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Default Homebuilding High Temp Furnace.


"dann mann" wrote in message
...
Seattle pottery supply.
Or even easier just buy somebody's used kiln for 150 bucks. Plug and
play. Look in the local paper. They are in our classifieds


I've been looking but the only one I have found is $1500 and comes with 3000
ceramic molds! I've been watching the classifieds for months now and have
only seen the $1500 one. I thought building one might not be so bad, I'll
get half way done and find a ceramic kiln for $150 :-(






  #11   Report Post  
RogerN
 
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Default Homebuilding High Temp Furnace.


"David Billington" wrote in message
...
I bought a Cal Controls 9400 controller with RS232 interface so that I
could monitor the temperature remotely and set the characterisitic
(setpoints etc) remotely. Haven't completed all the software for setting
data but the monitoring is OK.

You must have lots of time to write the code for microcontrollers for
this sort of app or do it frequently and have lots of source handy. I
program for PC and PDAs in C and C++ so will do some of that but making
my own controller when you can buy them for £160 ($240 ish) with
multiple programs capability and multiple setpoint per program. I would
buy one of those a use the time on the rest of the project.


I haven't looked at the more recent temp controllers, who makes the
programmable ones in the price range you mentioned.

I saw some kiln controllers that are set up to fire to different cone
numbers, not what I want. I was thinking of using a PIC16F877, just add a
crystal and it has ram, flash memory, analog to digital, PWM, serial
communications, .... all for $6.50. A temperature control PID routine
wouldn't be that difficult in Basic or C. Add an op amp ($1) to amplify
the thermocouples and it should be in business. The PIC's will drive an LED
directly from their outputs, so a Solid State Relay would be able to be
driven directly, no additional $0.25 transistor needed. The compilers have
routines for writing to LCD displays, reading/writing RS-232, Reading
keypads, Reading/Writing external Flash memories, etc. For me, the
electronics is part of the hobby I want to make some knives even though I
can buy a knife at Wal-Mart for less than $10. I think I can make a better
knife than I can buy at Wal Mart and I think I can build a more suitable
heat treating controller than can be bought for $500. I can even buy a loaf
of bread cheaper than I can make one in my bread machine, but the home made
bread is a lot better than the Wal-Mart stuff.



  #12   Report Post  
Mark Rand
 
Posts: n/a
Default Homebuilding High Temp Furnace.

On Fri, 22 Aug 2003 14:28:58 GMT, "RogerN" wrote:


"David Billington" wrote in message
k...
I bought a Cal Controls 9400 controller with RS232 interface so that I
could monitor the temperature remotely and set the characterisitic
(setpoints etc) remotely. Haven't completed all the software for setting
data but the monitoring is OK.

You must have lots of time to write the code for microcontrollers for
this sort of app or do it frequently and have lots of source handy. I
program for PC and PDAs in C and C++ so will do some of that but making
my own controller when you can buy them for £160 ($240 ish) with
multiple programs capability and multiple setpoint per program. I would
buy one of those a use the time on the rest of the project.


I haven't looked at the more recent temp controllers, who makes the
programmable ones in the price range you mentioned.

I saw some kiln controllers that are set up to fire to different cone
numbers, not what I want. I was thinking of using a PIC16F877, just add a
crystal and it has ram, flash memory, analog to digital, PWM, serial
communications, .... all for $6.50. A temperature control PID routine
wouldn't be that difficult in Basic or C. Add an op amp ($1) to amplify
the thermocouples and it should be in business. The PIC's will drive an LED
directly from their outputs, so a Solid State Relay would be able to be
driven directly, no additional $0.25 transistor needed. The compilers have
routines for writing to LCD displays, reading/writing RS-232, Reading
keypads, Reading/Writing external Flash memories, etc. For me, the
electronics is part of the hobby I want to make some knives even though I
can buy a knife at Wal-Mart for less than $10. I think I can make a better
knife than I can buy at Wal Mart and I think I can build a more suitable
heat treating controller than can be bought for $500. I can even buy a loaf
of bread cheaper than I can make one in my bread machine, but the home made
bread is a lot better than the Wal-Mart stuff.



You'll also need a MAX232 or similar for level shifting on the RS232

Mark Rand
RTFM
  #13   Report Post  
Richard Ferguson
 
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Default Homebuilding High Temp Furnace.

How hot do the ceramic kilns get? I guess I could add a temperature
control easily enough.

Richard


dann mann wrote:

Seattle pottery supply.
Or even easier just buy somebody's used kiln for 150 bucks. Plug and
play. Look in the local paper. They are in our classifieds
(San Diego) every week

  #14   Report Post  
=\\^.^/=
 
Posts: n/a
Default Homebuilding High Temp Furnace.

How hot do the ceramic kilns get? I guess I
could add a temperature control easily enough.


Temp of kilns is measured by numbered cones. The hottest commonly used cone
temperature is cone 10, used for stoneware and porcelain. It's about 2350*
F



  #15   Report Post  
Gary Brady
 
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Default Homebuilding High Temp Furnace.

How hot do the ceramic kilns get? I guess I could add a temperature
control easily enough


About 2300 degrees F.
Gary Brady
Austin, TX


  #16   Report Post  
Roger N
 
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Default Homebuilding High Temp Furnace.


"David Billington" wrote in message
...

I am not that familiar with the PIC family as there are so many. Can you
program any of the 16 series in C or basic, I thought the issue was
insufficient memory for high level langauge support. I agree that the
PID routine would be far easier in these languages than assembler. Last
time I looked I don't think I could find PID routines in the PIC
libraries. Some info is available on the web but in C or similar.


Here's a page with a list of PIC's supported by PicBasic Pro compiler.
http://www.melabs.com/products/pbp.htm

I wrote a program in "C" to integrate rate gyro information to make it a
position gyro, got it to fit in a PIC 16C84 with only 1K of instruction
memory. The $6 PIC I'm wanting to use has 8K instruction memory plus much
more ram, eeprom, etc.

MicroChip has application notes for servo motor motion control, the PID
routines are used in those application notes.

Looking at the communications capabilities of the temperature controls has
given me an idea of another possibility. Use a PIC to read and command the
temp. controller. That the temperature control would control the
temperature, but the PIC would change the temp control settings for what you
wanted to do. The Basic and C compilers for the PIC's have good serial
communications capabilities. I have a PIC right beside my computer that I
can plug in to RS-232 to read the A/D converter WITHOUT using any kind of
level converter.



  #17   Report Post  
David Billington
 
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Default Homebuilding High Temp Furnace.

That compiler would certainly open up some options by making development
time quicker. I can't justify the cost for the occasional time I use a
PIC though.
I'll have a look at the microchip app notes again for PID routines and
see what might be of use to me sometime. The PIC on rs232 must have good
diode clamping /zenering to cope with rs232 nominal +- 12V signal levels.

Roger N wrote:

"David Billington" wrote in message
k...

I am not that familiar with the PIC family as there are so many. Can you
program any of the 16 series in C or basic, I thought the issue was
insufficient memory for high level langauge support. I agree that the
PID routine would be far easier in these languages than assembler. Last
time I looked I don't think I could find PID routines in the PIC
libraries. Some info is available on the web but in C or similar.


Here's a page with a list of PIC's supported by PicBasic Pro compiler.
http://www.melabs.com/products/pbp.htm

I wrote a program in "C" to integrate rate gyro information to make it a
position gyro, got it to fit in a PIC 16C84 with only 1K of instruction
memory. The $6 PIC I'm wanting to use has 8K instruction memory plus much
more ram, eeprom, etc.

MicroChip has application notes for servo motor motion control, the PID
routines are used in those application notes.

Looking at the communications capabilities of the temperature controls has
given me an idea of another possibility. Use a PIC to read and command the
temp. controller. That the temperature control would control the
temperature, but the PIC would change the temp control settings for what you
wanted to do. The Basic and C compilers for the PIC's have good serial
communications capabilities. I have a PIC right beside my computer that I
can plug in to RS-232 to read the A/D converter WITHOUT using any kind of
level converter.




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