Build a Heat Treat Oven
I have a huge kiln but fear it is not the proper tool to heat treat parts.
So I've been doing some googling on building a proper front loading heat treat oven. I've found Dudley's Element Paper which takes the mystery out of the element part.
Seems that most DIY ovens are made with bricks. I'm considering using some Kast-O-Lite to cast the oven so I can get the thickness I want.
Has anyone here built their own heat treat oven?
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Built mine last summer. Tricky part was finding a cheap source of insulating fire brick (fragile and expensive to ship). Also regular firebrick is *not* what you want. IFB is what's used, as they insulate.
http://www.budgetcastingsupply.com/ has lots of info for DIY, as well as materials.
Thanks for the links. How did your build turn out? Anything you would do different with hindsight?
I've been doing a bit more googling and it seems commercial ovens use bricks or a combination of bricks and pourable refractory.
Ebay often has some nice new Digital Temperature Controllers for really good prices.
I bought a 800 centigrade unit for under $20 (overkill for a powder coat oven).
Add a sensor and a relay for very accurate temperature control.
Mine ended up being overkill, as the only local IFB I could find locally were 6.75" x 9" x 3" (local surplus place had them cheap), and I split a bunch down the middle to get 4.5" thick walls rather than the usual cover with kaowoll approach. Buttering all those faces with refractory cement was a royal pain, and I'd probably go the kaowoll route next time.
Here's a pic of it half finished:
I also did a vertical opening door with 4 levers to swing up while keeping the hot side facing the oven, which was more trouble than it's worth IMO. Then again, I just eyeballed everything...
Controller was from Auber Instruments via EBay and does the PID ramp soak thing. Heating element was also eBay and from a guy who would custom wind to your spec. All told, a fun project. And one of these days I'll actually use it! ;-)
I noticed that on commercial ovens the blocks that hold the elements seem to slide in a groove, I assume for easy replacement.
How did you cut the blocks?
The light insulating fire bricks are pretty soft. You can cut them with hand tools or with a table saw or router. It won't do your blade or bit much good, but old ones should work fine.
Originally Posted by BigJohnT
Old, dull wood saw goes through like butter. Dusty and abrasive, so personally I wouldn't want my power tools anywhere nearby. Also doing it outside is a good idea. Tweaking fit can be done with a utility knife / wood rasp / random scrap of metal. They're seriously soft, to the point that you can sink a thumbnail in them pretty easy.
hacksaw is one way....they will easily cut with handsaw, but I'd rather toss away a hacksaw blade than get a saw sharpened.
+ 1 on using IFB. I bought a hundred or so new from kijiji awhile ago for $1 each....they come up as best laid plans of potters fall by the wayside. Maybe one day mine will to as the best laid plans of a metalworker falls by the waysided.