Author Topic: Electric Heat Treating Oven  (Read 14998 times)

Offline Dawai

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Re: Electric Heat Treating Oven
« Reply #25 on: November 26, 2013, 06:49:55 AM »
Very cool.  Some of the guys around my area have went to liquid salt to temper things. I know nothing about it. Would like to learn more about tempering things.

A door on the back side, and you'd have a furnace capable of doing black smithing too. They do a piece of pipe with open holes on both ends to heat with. AS a electrician, sticking a metal "rod, tongs, or pliers" into a heater coil fired "something" is a possibility of getting a shock. Even a "fork" into a toaster, the coils make the fork a "transformer secondary" picking up the power in the coils and delivering it to you.

THE $27 PID I bought for my beer cooker can be re ranged for ceramic kiln temperatures. Rex100?? came with a SSR and 6' K type thermocouple. (yes I am shutting the door after the cow has left) might help someone else thou.

AND yes,  you are right, one side is "HOT" if you use the SSR to turn it on and off. I put a 10hp 4 pole relay in to switch it off, and a plug to totally disconnect it.
IF you wish to use a "cheaper" heating element, say a piece of stainless mig wire?? you can use a SSRV, like a SSR, but has a pot you turn to limit the power like a light dimmer, except for 75 amps for the one I have here.
I Hung a 24 foot Ibeam this morning in the ceiling by myself, programmed a Arduino this afternoon for a solar project, Helped a buddy out with a electrical motor connection issue on the phone, then cut up a chicken for Hotwings. I'd say it has been a "blessed day" for myself and all those around me.

Offline tom osselton

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Re: Electric Heat Treating Oven
« Reply #26 on: November 26, 2013, 05:12:57 PM »
Nice furnace you can take a look a this site for temp control it may help you out
http://fusedglass.org/learn/technical_tutorials
My sister in law made some fused glass  and knows I have Dad's kiln although it doesn't have a pid on it I was thinking  about e-bays anyways hope it helps.

Offline unc1esteve

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Re: Electric Heat Treating Oven
« Reply #27 on: November 28, 2013, 11:40:38 AM »
Tom,
I sorted out the problems with this controller.
On this model only the PV, the current temperature,
is able to be changed from C - F.  Everything else
remains in Celsius.  The instructions also talk about
turning on the autotune but it is always on.
The instructions are written as to assume the user
has previous experience with a PID.  No explanation
of the meaning of the terms used.

Offline unc1esteve

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Re: Electric Heat Treating Oven
« Reply #28 on: November 28, 2013, 12:06:29 PM »
Dawai,
Here is a good book for tempering.
http://www.bookdepository.com/Hardening%2C-Tempering-Heat-Treatment-Tubal-Cain/9780852428375

During the build I had thought about making a back door but decided to stay
with the original design.  During my research I found that not many use
an electric forge because the forging temperature is right at the maximum
operating temperature of an electric resistance oven.  Gas forges are faster.
Here is a link to a very nice gas forge that could be easily modified.


I have not finalized my wiring design.  I am thinking about adding a switch
and alarm to show that the door is open.  This controller supports a separate
alarm for the temperature setting.
I am using 110 VAC at the moment but may switch to 220 VAC to achieve
a higher temperature.  A second relay would be required.  I also have
a rotating switch as you described.

There are many PIDs out there.  They state their specifications.  I could not
find a glossary of the terms used.  I found it confusing trying to chose
a controller.  It seems that the ones sold by USA companies are more expensive
but are more USA user friendly.

It is never good practice to use a 220 VAC circuit using only one leg
for switching.  Both legs must be switched.  Sticking any metal object
into a live electrical circuit is life ending.

Offline unc1esteve

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Re: Electric Heat Treating Oven
« Reply #29 on: December 08, 2013, 06:45:18 PM »
After a few test runs I have noticed that the ssr relay must have a heat sink.
Also the nichrome wire will break anywhere it is touched by the hot aluminum.
I am thinking about enclosing the wire coils with fused quartz glass tube.
Just started to test with 220 VAC.

Offline unc1esteve

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Re: Electric Heat Treating Oven
« Reply #30 on: December 09, 2013, 09:33:53 AM »
Test with 220 VAC was unsuccessful.
All items say they are rated for 220 VAC, 20-25 A.
But all items failed including the nichrome wire.
Looking for the problem.

Offline Dawai

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Re: Electric Heat Treating Oven
« Reply #31 on: December 15, 2013, 03:38:51 PM »
THE kerr electromelt I had the coils were cast into the refractory. INsulated them and ?? Problem was it was a unit then, unrepairable.

I am working on a home-built 3d printer for form-casting models. Same thing, I may dip it into some thinned refractory, dry, then wrap the element, then redip, then cast around it.

I may build myself a home-built electromelt soon. I've scrounged the parts. Need the castable refractory.
I Hung a 24 foot Ibeam this morning in the ceiling by myself, programmed a Arduino this afternoon for a solar project, Helped a buddy out with a electrical motor connection issue on the phone, then cut up a chicken for Hotwings. I'd say it has been a "blessed day" for myself and all those around me.