I thought a few of you might be interested in this. A few years back, I purchased a powder coating gun from Harbor Freight and I picked up a little oven for 20 bucks at a garage sale. I started powder coating a lot of the stuff I was welding or machining but soon came to the conclusion that the oven was too small and the gun too weak for multiple coats. I looked around on the internet to see if I could find a bigger oven for a decent price. I looked for pizza ovens, scientific ovens, proofing ovens and all sorts of things. They all had their problems not the least of which was price. Too small, 3 phase power, not hot enough, too big or 1000 miles away.... So I decided to build an oven. I figured I'd want it to be 4'x3'x3'. But wait, what if I want to do a motorcycle frame? Or a bumper? Or a bike rack? The size then became 6'x3'x3'. I was going to make it out of 2 inch thin wall square tube. Some sites on the internet suggested 3 inch, but when I looked at my little oven from the garage sale, no where did it have more than 2 inches of insulation and it seemed fine. What would I sheet it in? I was going to go wit 20 gauge steel, but happened upon some 12 gauge aluminum sheets that were 42"x 77" in a scrap pile at the local metal place. Apparently they had been miss cut so they were selling for scrap price of .30 cents a pound.
The next question was heating. How would I do this. I took my little oven apart and picked up a convection oven at a garage sale for another 30 bucks and had all the heating elements and controls, plus convection fan that I would need. I then jumped on the internet to find some length of temperature rated wiring and sealing rope for around the door and was ready to start welding and cutting.
I found aluminum was easy to cut with a carbide blade in my circular saw. While taking apart the second stove, I decided to use the little window for viewing into the new oven.
I used the unbacked fiberglass insulation for between the inside and outside panels.
I used a power junction box to wire all my controls into. The access for the convection fan also acts as a air expansion release. The thermostats from one of the stove controls the 3 2200 watt electric burners in the oven. I also mounted a temperature gauge in the window for more precise readings. I even reused one of the lights to illuminate the interior of the oven.
I'm attaching some pics. Let me know what you think or if you have questions.