Building a Heat Treat Kiln

I decided that I needed a better way to control my heat treating. After looking at a few ovens/kilns online I decided that they looked pretty simple and I didn't want to spend $1,000+ so why not make one? I happen to do industrial automation and controls for mechanical and electrical systems for a living, so an oven is right up my alley. I got some 16 ga mild steel and cut out the basic shapes with a plasma cutter, then tacked them up to make a box.

Here is the bottom side of teh box, I added some little legs that will have adjustable height feet on them.

Here it is with the front door tacked on. The internal dimmension will be 18 inches long so I can fit decent sized blades in there.

And here it is mocked up with the bricks in it. There will be a layer of bricks on the top and a metal lid, with carrying handles. I already got some Kenthal A1 wire and wound an element, I need to install that and my control box. I will be using a PID controller with an SSR for the element. More to came!

 

Awesomeness. ....

 

Excellent :cool1 op

 

Looking forward to seeing how it comes out, and what kind of control you get out of it.

 

Nice!!

I ran dual SSR's and two separate elements. It seemed to make things more efficient overall vs one SSR and an element. I used an Auberins ramp/soak PID, but it was overkill and I should have just went with a standard unit. This is the one I used:

http://www.auberins.com/index.php?main_page=product_info&cPath=1&products_id=4

Great if you regularly heat treat high alloy stuff though.

Anyhow, my oven worked well enough for the time I was using it. Later I lucked onto a direct trade...one of my kitchen knives for a brand new Evenheat 22.5" unit and took it. It doesn't get any hotter than my old oven, but I have the peace of mind of knowing that my temperatures are probably more evenly distributed and accurate throughout the oven than they were with the old unit.

If you're curious or might possibly like an example of what I did (which you can either use for instruction, or what NOT to do lol), you can see my build here:

http://www.bladesmithsforum.com/index.php?showtopic=26893

Looking forward to seeing yours finished .

 

Cool! Looks like fun. I am familiar with Auber, they make some good stuff. I happen to do industrial automation and controls for a living so this project is right up my alley. I'll be pretty certain about my temps and performance as I have multiple ways of verifying everything. I can't wait to get this thing done! I have a stack of knives that are waiting for heat treat right now and this oven is the bottleneck.

 

Here is the heating element I made, it's Kenthal A1 wire. It's MUCH cheaper to buy the wire than it is to buy a made coil. I put a piece of dowel in my drill and wound this up, very easy. I then stretched this out so the coils were pretty evenly spaced.



Last night I did my first test run, the kiln isn't welded up and finished but I did make the electrical enclosure and wire that up. I had it limited to about 75% power and took it up to 550 Deg F before I went to bed, so far so good.

 

The only thing I got was SSR = solid state relay. The idea that you guys can actually put this together is crazy cool. I look forward to seeing this when it's done.

 

Latest update: I've used it twice to heat treat blades, works well! I finally got the door insulated properly and now I need to finish welding a few things before it's "done". I'll put the top on it then some handles, etc. More photos to follow.