A bit of backgound for those who don't know: TIG (Tungsten Inert Gas) welding is now formally called GTAW (Gas Tungsten Arc Welding), and MIG (Metal Inert Gas) is now called GMAW (Gas Metal Arc Welding). The new names started into use in the 1970's, and many of us who grew up in the "MIG and TIG" days still call those processes by their original names.
Welding is fascinating stuff. I have a friend -- another old guy -- who's a welding master. He's demonstrated cutting two aluminum Coke cans in half and GTAW welding the bottoms together. He's an extraordinary guy who runs an awesome machine shop, and I've never seen anyone else weld such very thin aluminum. You have to have the settings just right, or it simply makes holes. Another friend was a Marine Corps diver -- he enlisted during World War II -- and he learned to weld underwater.
For this chassis application, welding is certainly a possibility, and we do have a nice GMAW/GTAW rig that hasn't even been christened yet. But welding just doesn't appeal to me here. I don't want to paint when I finish, so grinding isn't a process I want to use. I do like the idea that there wouldn't be as many fasteners sticking out, but that's an aesthetic thing, not a functional need. I hadn't thought about GMAW spot welding; that's an interesting idea.
Still, I like the machine-screw fastening process because it gives me a chassis that can be completely disassembled. Also, I'm having a ball experimenting with punching and bending and using various materials, and especially trying out the rivet nuts. I'm teaching myself to bend metal to the dimensions I want, with the goal being to be able to cut a piece to size, punch the holes, and bend to final shape -- just like a production shop would.
And one final reason is that I want to produce a chassis that most MP3Car members could produce using only basic sheet metal tools. Not many will have access to a welding rig, where the tools I'm using are surprisingly inexpensive.
This garage shop is really almost a laboratory for us -- a place to try new things and learn new skills and processes. It's definitely not a production shop, but I suspect that's because we don't much care for repetitive tasks. We like to keep finding new mistakes to make.