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Seastar
08-26-2007, 01:24 PM
Does anyone know of a small (6x6x12 aprox), inexpensive heat treat oven.
All of my searches turn up larger units that cost well over $1ooo.
I have been using the usual home shop methods like my coal forge and a bucket of brine, or an oxy torch, or my wifes oven and even the gas grill on ocasion.
I would like to have a method that is more controlable for tools, knife blades, springs, etc.
All input will be cherished!
Bill

Your Old Dog
08-26-2007, 02:03 PM
Cherish this!

Have you thought of a ceramic kiln as used by potters. There are also wax burn out ovens used by jewelry makers and they pop up used from time to time? (you can use Tempil sticks to know what temperature you're at.)

Weston Bye
08-26-2007, 02:21 PM
For less than 20 bucks you can buy enough firebrick to stack together to heat treat tool-sized pieces. You should be able to achieve 2000 even with a propane torch. I've done it with bricks stacked to form a 4x4x12 space. But, what you really need to add to the setup is a thermocouple temperature probe and digital thermometer so that you know where you really are, as judging the color of the steel is very subjective. The thermocouple is especially important when drawing temper, as a few hundred degrees may result in several points of hardness.

Even though the setup is not automatic, the temperature in the enclosed area varies relatively slowly, and you learn to tweak the gas control for best response.

dp
08-26-2007, 02:24 PM
You can make a portable kiln with kiln bricks, screw-in kiln heaters, and a light dimmer. Cal-Rods for kitchen ovens work, too. Stack the bricks against a wall when you're done firing and it takes up no room at all.

BadDog
08-26-2007, 02:54 PM
Our local club is building casting furnaces using shop/club built burners and ovens. One of the guys has been successfully using a furnace/burner of this design for several years(?) I think. Reportedly works very well. I personally still have far too much climbing left on the machinist learning curve to start another steep climb on casting, but I am interested in having a budget heat treat oven, so I opted in for a modified version to build the oven. Unfortunately, I didn't make the meeting where the burner was built, but you can see the meeting page/pics here (http://www.valleymetal.org/Burner%20Build/). We'll be building the furnace/ovens at a later meeting from steel 5gal buckets and refractory materials. The casters will build vertical ovens to hold the crucible, and the heat treaters (I think?) are building a horizontal pass thorough with centralized tangential burner ports.

tenfingers
08-26-2007, 03:10 PM
I looked into buying one a while back and these were the least expensive new ovens that I could find. Not really inexpensive, but under they are under $1000.

http://www.ottofrei.com/store/home.php?cat=1920

I waited until the urge to buy faded, so I can't tell you if they're any good.

10F

Alistair Hosie
08-26-2007, 03:17 PM
Potters kilns tend to be too large to be comercially viable they have to hold a lot.You obviously will not be needing such a large expensive to operate and run kiln.I suggest yoou try under Dental on ebay as Dental technicians use smaller wax bur out kilns.I hope you find something they are too expensive new, so buying a preowned one is best In my humble opinion.good luck Alistair

dp
08-26-2007, 03:25 PM
Our local club is building casting furnaces using shop/club built burners and ovens.

That is a pretty nice burner - I wonder if dimensions are available anywhere, and information on the gas jet in particular.

BadDog
08-26-2007, 03:32 PM
It came from the book that is shown in one of the pictures. Our local member has built several and "hot rodded" them to get even better performance.

rkepler
08-26-2007, 03:42 PM
I have a nice front loading kiln from Olympic, with a digital controller it makes a handy heat treat furnace. I don't think the make the same model, but it's similar to some of the models on this web page: http://www.greatkilns.com/electric_front_loading_kilns.cfm

Mine is front loading and side hinged, the model that they have that's got the guillotine lift looks a lot handier. Don't get one where the opening is on the top or where the door hinges down - you're going to be reaching into the kiln when everything is radiating at 1700+ degF and it sucks to reach over that. The side hinge is hard enough, the guillotine lift has the heat from the door radiating away from you when open, and that'd be real nice.

The electronic control is really handy, set the ramp, final temp and soak time and let it rip. If you can try getting one that uses 240V, I limited myself with a 120V system and it can take some time to get up there and has some trouble maintaining the top temperatures without an additional blanket.

SGW
08-26-2007, 07:27 PM
I think Brownell's www.brownells.com sells a small heat-treat furnace made by Neycraft. I think it's around $600, although I may be remembering incorrectly. Not cheap, but better than a thousand.

lazlo
08-26-2007, 08:23 PM
If you're on a tight budget, you can buy a laboratory or dental Muffle Furnace for a song on Ebay.

I bought a Blue-M M20A muffle furnace for around $130, and that wasn't an extraordinary deal. It's the bigger brother to this one, it has a 6"w x 10"d x 5"h chamber, if that's big enough for you

This Blue-M is in lousy shape, and the heat shields are missing, but you get the idea:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=260147891143
http://i6.ebayimg.com/04/i/000/a9/82/c994_1_b.JPG