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SteveC
05-17-2003, 01:39 PM
Has anyone made or acquired cheaply a small heat treat oven? Is it practical for the home machinist? Gas or electric?

Steve

ibewgypsie
05-17-2003, 03:02 PM
They have more uses than you might imagine, Heat-press fits of pistons. Wax burnout of investment for casting. Heat annealing parts. Heat treatment of parts and knives.
I built one for a friend, it has been a while. He used casting parts with a controller, a opto-22 solid state relay, and a formed element of mig wire.
To stop the wire from just burning in two he uses a triac, a resistor and a diac. Very simple and cheap. (like him)
He speaks of demagetizing blades, holds temperatures for hours. Has a castable refractory walls in his oven. It is all greek to me cause I was not interested at the time.
Controls are available at www.budgetcastingsupply.com (http://www.budgetcastingsupply.com) as is the refractory, but it costs more to ship than to purchase, You can check around the boiler repair companys and.. the farm supply..
A old wood heating stove is already made up for you, if you want a fast way out. you can melt aluminum at the temperatures you can achieve with a annealing oven.
Be forewarned sticking a metal probe or tongs into a operating oven can result in a massive shock, induced voltages can kill. It happens everyday when someone wants to stick a fork into a heating toaster somewhere in America.

Alistair Hosie
05-17-2003, 04:22 PM
Ibew why should someone stick a fork into a toaster?

ibewgypsie
05-17-2003, 04:27 PM
cheap toasters stick. Toast burns.

Cass
05-17-2003, 04:31 PM
You can stress relieve aluminum in a normal household oven which goes to 500F and depending on the steel you can do some stress relief on steel.

We used ot put a better control on a regular household electric oven and run it up to about 800 F. to clean parts for use in vacuum systems and I have seen that done to do hot dip galvanizing on small parts buy just putting a pot of zinc in an oven set up out in the yard. New heating element in an old stove with a wider range control is a real cheap way out. Throw in some better insulation and a pipe for nitrogen flow and you can do most anything.

An electric potter's kiln is pretty handy for higher temperature and they are relatively cheap and often available for sale in the hobby section of the want ads.

ibewgypsie
05-17-2003, 04:49 PM
Cass...

Warning, some ovens have fiberglass insulation around them. Maximum temp around 500 degrees, after that it decomposes into a obnoxious gas and crystaline structure.
The ones with cer-wool fibre insulation are good till about 1800 if I remember correctly.


Neat ideal.

jfsmith
05-17-2003, 08:40 PM
I do my own heat treat and build and repair HT ovens. Mine are simple one temp range, one or two controls, you supply the thermometer.

I do HT, lost wax, smelting and couple of other things with mine. For the home shop, you can build a small electric oven that will work. You just need to know what you want it to do and what it will do.

If you come across an ceramic kiln at a yard sale buy it! They can be fixed cheaply and will last years.

I have a gas fired oven, that works for things like ATS-34. But mine is too hard to control for 500 to 900 degree range F.

If you want to build a gas fired one, try emailing Jay in West Virginia,

xmas4lites@earthlink.net

He can sell you all of the stuff for a cheap price and you need to made a sheet metal box.


Jerry