Work on the oven continues. I found several how-tos on the web about building your own powder coat oven, and I decided to use steel framing as I mentioned in a previous post. Most of the how-tos use steel rivets to hold the framing together.
Initially I decided to use screws to hold the framing together, and then replace the screws with rivets. Steel rivets, as it turns out, are expensive and not easy to come by, thus the decision to go with self tapping screws. So I squared up the base and grabbed my power screw driver.
Four screws later, I said forget that and tried to figure out other options. Once the screws were in place, I didn't feel that the structure held its angular integrity very well. After considering my options, I decided welding the pieces together was the best way forward. At first I was going to tack the pieces together with the MIG since it's my welder of choice, but welding thin galvanized steel isn't fun with the gases and fumes that it creates. In the end I decided on hauling out my beast of a spot welder from hibernation.
I bought the spot welder for next to nothing from a body shop that was going out of business a few years back, but I haven't used it all that much. One of the problems with it is that it draws 25A while welding, and the service to the house is 25A. So whenever I need to weld I have to go around the house and shop and turn everything off, including lights and heater. I still blew a fuse today - forgot to turn off the compressor. The spot welder uses shop air to clamp the two pieces together before applying the power (two stage trigger) and the two metal pieces are fused.
The end result turned out rather good, and with both sides spot welded it made for very strong corners.
Soon after I had a perfectly square rectangular base. The base is 120x100cm (47x40in). The inside of the oven will be 100x90x100cm (40x35x40 in).
The cross beams were spaced at 30cm (12in) and spotted in place.
The end result was an extremely rigid base made from steel studs.
And another shop tip - do not leave your digital camera on a spot welder while you're working.