looking for electric heat treat oven insperation

J

john0270

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Feb 9, 2008
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I want to build a couple electric heat treating ovens, a smaller one at first, and then if that works out a larger one(say 30-35" long), but using the same controll's for both. My goal is just more accurate heat treating of carbon steel blades, mostly 5160, and to eventually start using stainless.

If anyone has built there own, I would be happy if you posted pictures, general likes/dislikes about what you did, and maybe were you purchaced the supplies. I am in the middle of nowhere canada and there is no such thing as refractory ect ect ect within a 300mile radius that I can find.

Would like to keep the total price of all the supplies under $600 if possible. To fab the body won't be a factor so disregard that as a cost.

later
John from saskatchewan
 
THIS thread has some great information in it from when I built my heat treating oven.

THIS is arguably the most referenced tutorial out there. For some reason the tutorial is not up right now, but you might check back later.

Here are some pics of the oven I built a few years ago.

I patterned the HT oven I built from the British Blades tutorial with some changes. For instance, I used angle aluminum for the frame and built the sides and bottom of the body out of one folded sheet of weld steel to improve heat retention. I used a PID and K type kiln thermocouple from ebay. Here's a few pics of the oven I built a while back. It will hold temperature to +/- 1 degree according to the PID once soaked at temperature and has a max range of close to 2300F. It's about 14" deep.

RandomPicsNathansShop034.jpg


IMG_6499.jpg


RandomPicsNathansShop097-1.jpg


The door's not that pretty, but it insulates very well. The seal is made from high temp tadpole gasket fastened with stainless stripping and stainless screws. The door itself is filled with high temp glass fiber insulation.

You can order refractories from Darren Ellis.

I bought my kanthal wire from Budget Casting Supply.

And you can order controllers and SSR's from Auber Instruments.

I don't know if all of these guys ship to Canada, but it's worth looking into.

Also, for in the $600 range, you may be able to find a Sugar Creek oven.... I think I spent like $300 total on mine.

--nathan
 
This is my HT-oven
The oven control is made from an old computer case and contains 2 PID controllers for driving 2 different ovens at the same time, one for hardening and one for tempering.
The controller to the left is a Eurotherm 2216e controller with basic ramp-functionality, the other is a noname $40 eBay controller.

Heating element regulation is made with two 25A SSR, also bought from eBay.

In Sweden “all” houses have 400V 3-Phase/230V single phase so the oven control is fed with 3 phases, one for each oven and the last phase is used for the controllers and cooling fans for the SSR´s.
Fuse size is 16A which lets me use 3680W on each oven @ 230V. The oven in the picture is only 2100W due to the small size.

My first oven is too thin to be used as a HT-oven, 75mm insulation in the walls and 100mm in the roof is not enough. I´m building a bigger HT-oven with more insulation and about 3kW for better performance.

Interior:
ugn001.jpg


Oven to the left, controllers to the right:
ugn002.jpg


Chefs knife in the oven:
ugn003.jpg
 
If I had to build mine over again, I think I'd do a lift-top rather than a front-open. Front-opening are probably safer and more likely to keep their heat, but repairing or replacing the elements is a pain in the butt unless your chamber is big enough to squeeze two forearms in. Rashid11's video walkaround.
 
Same here. My oven's top is just a lid and just lifts off. After the lid is off, you just remove the fire bricks on top of the oven and you have access to the chamber. I just replaced the coils in my oven about 2 months ago.

As for building an oven, if available, use soft fire brick. It insulates well and reflects heat well and is very easy to shape, though somewhat fragile.

--nathan
 
The British Blades page is down but here is the google cached image of the page: LINK

No pics but it does have the link where you can download the pdf version of the tutorial.
 
Thanks guys, should be enough information for me to order up some supplies and work out the details in the mean time. Oh, about firebricks If I use 3" soft fire bricks, it should be enough thickness right??? should I add another inch?
 
I have a top-loading oven but the kanthal wire has yet to require replacing. Maybe because I used thicker wire? I thought my 18" long (internal) oven would be overkill, but it turns out that sometimes I need every inch of it. Build it bigger than what you think you need, just in case.
 
Are you going to purchase kanthal ready coiled for your oven or are you going to wrap it yourself? Not trying to hijack your thread but I am going to start an oven project as well and am trying to figure out the element...
 
I would probably wrap it myself, I would probably just use a 12x36 lathe.....

Yeah I want to build a smaller one first, and then later a larger one... with short swords ect in mind
 
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