Electric Heat Treating Oven

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Meldonmech:
Hi
A very interesting project, detailing all the equipment and where you sourced it. Have you a total cost for the build, and have you any heating costs compared with propane.
Well Done David

DavidA:
It looks as if you can run the oven with the door open and the power turned on; even if by accident.

Is this so ?

Dave.

unc1esteve:
A final coat of paint and this project is complete.
I am satisfied, more than satisfied, I started out
wanting a simple heat treating oven for a few small
parts. Now I have that and more. I did not intend
to use this as a foundry but it works well. Precise
control over temperature if I can figure out how to
set the PID. I have searched for pid terminology
but can not find a clear explanation of the settings.

Conclusions.
1. I used 16 ga wire as I first wanted to use 220 VAC. But
this works good on 110 VAC.
2. I made the coil as long as possible. I put the coil on all four
sides. I wanted as much resistance as possible, more heat.
3. The coil expands when hot. The top coil may slip out of
position when hot. A nichrome wire across it holds it in place.
4. The coils are electrically charged when in use. The expensive
ovens use glass tubes to enclose the coils. Also safety switches.
I did not put an automatic off switch on the door.
5. The lack of noise and great heat when being used as a furnace
makes this deceptive. Hot and molten metal are very dangerous.
6. My first idea of a simple switch control is not a good idea for
heat treating. But it will work well for the furnace with a pyrometer.
7. With the damage in shipping and a few mistakes I have almost enough
material to make a second oven.
8. Use hard brick for the exposed areas as they will get damaged. They
can be cut with masonry blades.
9. PID control is good. Make sure to match the correct temperature range
on the controller and the thermocouple.
10. Casting Is Fun.

unc1esteve:
Meldonmech,
Once I realized that my first ideas were not very good I did not keep track of costs.
I do not have an ammeter in the range for this oven.
I will do some math.

unc1esteve:
DavidA,
Yes, the power can be left on by accident.
I put a switch in line with the ssr relay so I could
have power to the PID for setting.
One of the heat treating projects I have is a set of
12" mortise chisels with the handles attached. I saw
a need to use the oven with the door open or detached.
I made a temporary label for the control panel. It shows
the coil switch and the indicator light.
It would be a simple matter to add safety switches and alarms.

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