I have never personally seen the material you mention being used in building an oven. But I do know there are more way than one to do the same thing. You are thinking the same way as I with the fan mounted internally and the motor externally, thus eliminating any direct contact with an exposed spark. One thing I have seen, the fan, shaft and motor should not be directly linked with each other. The shaft will carry heat into the motor and possibly damage it, whether or not this is true I don't know. Most industrial units look to be mounted directly, so your own commonsense be used with this. As for elements, if you have enough airflow, the oven should be even heat all the way through, as long as you diffuse it somehow to be blown where the cold, somewhat remote spots of the oven are located. I think that is just something you have to play with and see what works and what doesn't. Heat rises, so in theory the top should be the hottest, the bottom the coldest.
My smaller oven is just made out of 18 gauge sheetmetal, on a 1 1/2" angle iron frame, with 3/4" square tube making the frame for the oven itself. It has 3" insulation all around sandwiched between the inner oven walls, and the outer skin. All frame work was welded together.
My larger oven is made of 4"x4" square tube, with 18 gauge panels, 4" thick walls. The reason for this monstrosity is I planned on moving it from the beginning, so I built it like a tank. My shop is just too small, and I plan on moving to a larger location for my work with PCing.
Your idea on creating a multiple sized oven is a good idea, but you may run into some problems trying to circulate the air properly. Say your oven has 5 chambers, you have circulation running for a big piece using all five chambers. If you do a small piece and only need one chamber used, you airflow is going to be different. Maybe your rheostat idea may work, but I see you may be playing with that bit for a while to get it just right. Go for it, but make sure you really need it. Good luck
P.S. ----- Non-Stick, as I said with the 100kv homemade gun, commonsense kicked in and I will buy one instead! lol
And everyone, I must say non-stick is a huge help on this board for all involved with Pcing, Give him a hand!!!!!
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