I am in the process of cleaning up the place for a blacksmith meeting next
Saturday. One of the other members will do the main demo, making a pair of
tongs. But I, as host, am expected to do some stuff, too. And I have
plenty of things from which to choose:

Demo running a couple of generators from my Chinese wood chip Gasifier
---not much metal content, but might be interesting to some

Demo the use and making of blacksmith anvils from pieces of railroad rail
--- I will have one piece set up to cut the basic shapes w/torch
--- One set up on Mill to show truing the face
---One set up on a stand to show truing w/ angle grinder
---One set up on surface grinder to show finish grinding of face
---One set up on a stump to show that they really can work, as long as you
can keep it from moving
---Several pieces on a table to show/explain sizes/weights of rail

Show off trip hammer collection

But here's the question and intro to it:
Several years ago a guy drove up the driveway and unloaded a 5KW
Westinghouse induction heater made in the 50's or 60's. It is about 4 feet
cubed. Tube type. It's mostly a 5KW radio station transmitter tuned to a
lower frequency, I think.
I have never fired it up. It takes about 50 amps of single phase 220 to
run it. And a water supply to cool the output coil. I think I will try to
get it going for the demo.
It came with only one output coil, but that one is about 4 inches long,
with an ID of about 2 inches, so I should be able to heat 1 inch bars pretty
well. -----IF it works at all. The manual tells me that there's about
10,000 volts running around inside, so I think I will keep one hand in my
pocket.

Anyway, are any of you guys fooling around with induction heating? We had
some guys from Ameritherm up here 4 or 5 years ago demonstrating a 5KW solid
state unit that was about 1/20th the size of "my" machine, but it was about
$28K retail. Now the Chinese have a 5KW knock off of it for about $3K. A
friend of mine in AZ bought one and it exceeded his (somewhat low)
expectations.
So, what experiences do 'yall have with this method of heating things?

Pete Stanaitis

In article ,
"Pete S" wrote:

I am in the process of cleaning up the place for a blacksmith meeting next
Saturday. One of the other members will do the main demo, making a pair of
tongs. But I, as host, am expected to do some stuff, too. And I have
plenty of things from which to choose:

Demo running a couple of generators from my Chinese wood chip Gasifier
---not much metal content, but might be interesting to some

Demo the use and making of blacksmith anvils from pieces of railroad rail
--- I will have one piece set up to cut the basic shapes w/torch
--- One set up on Mill to show truing the face
---One set up on a stand to show truing w/ angle grinder
---One set up on surface grinder to show finish grinding of face
---One set up on a stump to show that they really can work, as long as you
can keep it from moving
---Several pieces on a table to show/explain sizes/weights of rail

Show off trip hammer collection

But here's the question and intro to it:
Several years ago a guy drove up the driveway and unloaded a 5KW
Westinghouse induction heater made in the 50's or 60's. It is about 4 feet
cubed. Tube type. It's mostly a 5KW radio station transmitter tuned to a
lower frequency, I think.
I have never fired it up. It takes about 50 amps of single phase 220 to
run it. And a water supply to cool the output coil. I think I will try to
get it going for the demo.
It came with only one output coil, but that one is about 4 inches long,
with an ID of about 2 inches, so I should be able to heat 1 inch bars pretty
well. -----IF it works at all. The manual tells me that there's about
10,000 volts running around inside, so I think I will keep one hand in my
pocket.

Anyway, are any of you guys fooling around with induction heating? We had
some guys from Ameritherm up here 4 or 5 years ago demonstrating a 5KW solid
state unit that was about 1/20th the size of "my" machine, but it was about
$28K retail. Now the Chinese have a 5KW knock off of it for about $3K. A
friend of mine in AZ bought one and it exceeded his (somewhat low)
expectations.
So, what experiences do 'yall have with this method of heating things?

Beware the output coil. It will have very high RF voltages on it. Do
not handhold the bar being heated.

What does the nameplate say? Frequency is particularly useful to know.

How many turns does the output coil have?

Joe Gwinn

Coil = 5 turns.
Frequency = 100 kilocycles

I thought the output coil voltage would be pretty low, like 5 volts or so.
The coil resistance has to be pretty low.
The guys from Ameritherm did handhold the samples that they heated. That
was part of the demo; to show how the machine heated the end in the coil so
fast that the handheld end didn't get very hot.

Pete Stanaitis
----------------

Pete Stanaitis

"Joseph Gwinn" wrote in message
...
In article ,
"Pete S" wrote:

I am in the process of cleaning up the place for a blacksmith meeting
next
Saturday. One of the other members will do the main demo, making a pair
of
tongs. But I, as host, am expected to do some stuff, too. And I have
plenty of things from which to choose:

Demo running a couple of generators from my Chinese wood chip Gasifier
---not much metal content, but might be interesting to some

Demo the use and making of blacksmith anvils from pieces of railroad rail
--- I will have one piece set up to cut the basic shapes w/torch
--- One set up on Mill to show truing the face
---One set up on a stand to show truing w/ angle grinder
---One set up on surface grinder to show finish grinding of face
---One set up on a stump to show that they really can work, as long as
you
can keep it from moving
---Several pieces on a table to show/explain sizes/weights of rail

Show off trip hammer collection

But here's the question and intro to it:
Several years ago a guy drove up the driveway and unloaded a 5KW
Westinghouse induction heater made in the 50's or 60's. It is about 4
feet
cubed. Tube type. It's mostly a 5KW radio station transmitter tuned to
a
lower frequency, I think.
I have never fired it up. It takes about 50 amps of single phase 220
to
run it. And a water supply to cool the output coil. I think I will try
to
get it going for the demo.
It came with only one output coil, but that one is about 4 inches long,
with an ID of about 2 inches, so I should be able to heat 1 inch bars
pretty
well. -----IF it works at all. The manual tells me that there's about
10,000 volts running around inside, so I think I will keep one hand in my
pocket.

Anyway, are any of you guys fooling around with induction heating? We
had
some guys from Ameritherm up here 4 or 5 years ago demonstrating a 5KW
solid
state unit that was about 1/20th the size of "my" machine, but it was
about
$28K retail. Now the Chinese have a 5KW knock off of it for about $3K.
A
friend of mine in AZ bought one and it exceeded his (somewhat low)
expectations.
So, what experiences do 'yall have with this method of heating things?

Beware the output coil. It will have very high RF voltages on it. Do
not handhold the bar being heated.

What does the nameplate say? Frequency is particularly useful to know.

How many turns does the output coil have?

Joe Gwinn

On Jun 12, 1:21*pm, Joseph Gwinn wrote:

Beware the output coil. *It will have very high RF voltages on it. *Do
not handhold the bar being heated.

Joe Gwinn

Hmmm... I hold them all the time.... shrug

On 2011-06-13, Pete S wrote:
Coil = 5 turns.
Frequency = 100 kilocycles

I thought the output coil voltage would be pretty low, like 5 volts or so.
The coil resistance has to be pretty low.

Yes -- but the coil inductance could raise its impedance
significantly, allowign higher voltages.

However -- with 5 turns and only 100 KHz, probably not that
significant. Of course the inductance is also a function of size (turns
diameter) as well as the number of turns.

The guys from Ameritherm did handhold the samples that they heated. That
was part of the demo; to show how the machine heated the end in the coil so
fast that the handheld end didn't get very hot.

Probably pretty low voltage, then.

Enjoy,
DoN.

--
Remove oil spill source from e-mail
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 ---

DoN. Nichols wrote:
On 2011-06-13, Pete S wrote:
Coil = 5 turns.
Frequency = 100 kilocycles

I thought the output coil voltage would be pretty low, like 5 volts or so.
The coil resistance has to be pretty low.

Yes -- but the coil inductance could raise its impedance
significantly, allowign higher voltages.

However -- with 5 turns and only 100 KHz, probably not that
significant. Of course the inductance is also a function of size (turns
diameter) as well as the number of turns.

The guys from Ameritherm did handhold the samples that they heated. That
was part of the demo; to show how the machine heated the end in the coil so
fast that the handheld end didn't get very hot.

Probably pretty low voltage, then.

Might still want to be careful around something so old. Who know's what
voltages are leaking out of that thing.

In article ,
"Pete S" wrote:

Coil = 5 turns.
Frequency = 100 kilocycles

I thought the output coil voltage would be pretty low, like 5 volts or so.
The coil resistance has to be pretty low.
The guys from Ameritherm did handhold the samples that they heated. That
was part of the demo; to show how the machine heated the end in the coil so
fast that the handheld end didn't get very hot.

While the DC resistance is essentially zero, the inductive reactance
will be significant, and this is what will determine the voltage needed
to achieve 5 KW. Anyway, now we can do the numbers:

The approximate inductance of a 5-turn coil 4" long and 2" in diameter
is 0.76 microhenry. (This from one of the many web calculators which
solve the equations used for design of RF coils:
http://hamwaves.com/antennas/inductance.html. I assumed that the
conductors are 5 mm in diameter.)

The AC reactance at 100 KHz is about 0.48 ohms. To develop 5,000 watts
across this reactance requires a current of 102 amps, for a voltage drop
of 49 volts, which would not be especially dangerous.

This is true if the induction heater has a RF transformer output. If
the coil is instead part of a resonant tank circuit, the unloaded (no
workpiece) Q is going to be about 100, so the voltage across the tank
will be (100)(50)= 5,000 volts at 100 KHz, which may well be dangerous.

Given that this is an industrial machine from Westinghouse, with any
luck it has transformer output. But it's best to be sure.

Do you know any radio amateurs? There should be a ham club nearby, and
one of the old-timers (gray enough to know what a tube is and to have
worked on a tube transmitter) will make short work of it.

Joe Gwinn



Pete Stanaitis
----------------

Pete Stanaitis

"Joseph Gwinn" wrote in message
...
In article ,
"Pete S" wrote:

I am in the process of cleaning up the place for a blacksmith meeting
next
Saturday. One of the other members will do the main demo, making a pair
of
tongs. But I, as host, am expected to do some stuff, too. And I have
plenty of things from which to choose:

Demo running a couple of generators from my Chinese wood chip Gasifier
---not much metal content, but might be interesting to some

Demo the use and making of blacksmith anvils from pieces of railroad rail
--- I will have one piece set up to cut the basic shapes w/torch
--- One set up on Mill to show truing the face
---One set up on a stand to show truing w/ angle grinder
---One set up on surface grinder to show finish grinding of face
---One set up on a stump to show that they really can work, as long as
you
can keep it from moving
---Several pieces on a table to show/explain sizes/weights of rail

Show off trip hammer collection

But here's the question and intro to it:
Several years ago a guy drove up the driveway and unloaded a 5KW
Westinghouse induction heater made in the 50's or 60's. It is about 4
feet
cubed. Tube type. It's mostly a 5KW radio station transmitter tuned to
a
lower frequency, I think.
I have never fired it up. It takes about 50 amps of single phase 220
to
run it. And a water supply to cool the output coil. I think I will try
to
get it going for the demo.
It came with only one output coil, but that one is about 4 inches long,
with an ID of about 2 inches, so I should be able to heat 1 inch bars
pretty
well. -----IF it works at all. The manual tells me that there's about
10,000 volts running around inside, so I think I will keep one hand in my
pocket.

Anyway, are any of you guys fooling around with induction heating? We
had
some guys from Ameritherm up here 4 or 5 years ago demonstrating a 5KW
solid
state unit that was about 1/20th the size of "my" machine, but it was
about
$28K retail. Now the Chinese have a 5KW knock off of it for about $3K.
A
friend of mine in AZ bought one and it exceeded his (somewhat low)
expectations.
So, what experiences do 'yall have with this method of heating things?

Beware the output coil. It will have very high RF voltages on it. Do
not handhold the bar being heated.

What does the nameplate say? Frequency is particularly useful to know.

How many turns does the output coil have?

Joe Gwinn