Electric Heat Treating Oven

The Shop > Metal Stuff

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unc1esteve:
The ceramic board arrived.
I removed the sheet metal skin and
applied the board. I ran the element wires
between the insulation brick and the board.
I connected the leads to the power supply with
small bolts and washers after testing the wire and bolts.
I re-used the sheet metal
by bending the corners back flat.
I made a ridged frame of an old bed frame.
I added legs to the back so the oven could be
used as a furnace. Then did a test run to see
how hot the metal sides would get. Let it heat for
about 45 minutes. The sides were again too hot to
lay your hand upon. But I am satisfied that no fire
will ensue.
The PID control I showed earlier was for demonstration.
It does not have the needed heat range for this oven.
Still looking for the correct controller.
As the heating coils are exposed and are electrically hot
when in use it is always a good idea to turn off the power
before entering the chamber. As I plan on using the oven
with the door open at times I have not installed an
automatic shut off switch.
I attached the door with a removable hinge. I also ordered
a small piece of glass for a site hole.
http://www.skylinecomponents.com/In-Stock_FusedQuartzDiscPlate.html

unc1esteve:
I need to get high temperature paint.
I added a high temperature thermocouple.
I made a mock up of a door latch.
While I was doing this I thought a test firing
of aluminum would be in order.
I made a crucible of 1/4 steel pipe and a few
tools. I collected safety equipment. This oven
can be deceiving. There is no harsh bellowing
noise. There are no flames issuing forth. It is
easy to forget how dangerous it is.
That picture of doubleboost's mate's face shield
with the brass splash on it scares me.

unc1esteve:
I made an ingot mold.
I purchased some bentonite clay for greensand
as I did not want to deal with oil.
http://www.ebay.com/itm/15-pounds-BENTONITE-HEALING-CLAY-Best-internal-external-DETOX-Guaranteed-/221310369189?pt=LH_DefaultDomain_0&hash=item3387203da5
I used the recommended play sand.
http://www.quikrete.com/productlines/SandPremiumPlay.asp
I used 4% water by weight.
Mixed together in small containers first.
I made a pair of small flasks of wood and two ingot patterns.
I figured that this would be a good time to test things
and get used to the feel of casting as I had not done this before.

unc1esteve:
While waiting for the PID controller I made some test
ingots. I made one change at a time to see the
difference, such as no vents or vents.
A peek through the site hole.

unc1esteve:
This is the PID I ordered.
http://www.ebay.com/itm/161111236826?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649
The thermocoupler.
http://www.ebay.com/itm/181187310615?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649
And the SSR relay.
http://www.ebay.com/itm/Solid-State-Relay-SSR-25DA-25A-3-32VDC-Output-24-380V-AC-Solid-State-Module-USA-/161111607581?pt=LH_DefaultDomain_0&hash=item258300091d
I painted the oven and made a box for the controls.
I added a cut off switch for the coil so I could set the
PID without the heat on, and to open the door without
turning the power to the PID off.
The PID instructions are a little confusing.
I have it wired for 110 VAC but it could also control 220 VAC to
the coil by adding another relay.

I decided to behave like our government and pass the cost of
this project to the third and fourth generations.

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