While this isn't exactly what most of you would consider "metalworking", it's probably as close as I'll get for awhile (plus it was a great excuse to buy a welder), and I had alot of fun in the process.
I wanted to restore and motorize a circa 1905 Chattanooga #11 (Improved) sugar cane mill I got off a guy in NC. Originally these things were turned by mules/horses, I wanted to run it via electric motor, so you need to get the RPMs down pretty low (for this mill, down to about 8-9 RPM), while keeping the torque up high enough to still crush cane. This is what it looked like when I first got it, hadn't been used in decades are some of the bolts were frozen.
A bunch of penetrating oil and tap-tap-tapping finally got it into pieces. I had to replace some of the original square headed bolts which were completely rusted thru.
A cheap siphon sandblaster worked wonders:
One problem was the base plate collar around the king shaft well was missing a chunk of cast iron.
That was beyond my skill level, and I had to hunt around Houston quite a bit before finding someone I trusted to repair it without cracking the plate in half. He wanted $400, but we settled on $100 and a cooler full of cold beer (outdoor shop, Houston summer heat. He immediately said "yes" when I made the offer), and I thought he did a pretty nice job:
A bit of International Harvester red paint helped alot:
One issue was the original bronze shaft bushings - they were still in reasonable shape, but I wanted to replace them with UHMW, because then I could run it dry (without lubrication). No matter how well you cover the bottom shaft boxes, the cane juice will mix with the (food grade) oil, and it's a mess. You can avoid all that with UHMW bushings, and they wear quite well. I didn't know how to mold UHMW, but after a couple of weeks of experimenting I figured out a process that worked for me. At roughly 290 degF in the oven it will start turning totally clear (take a long time to heat up). At this point it has the consistency of a piece of truck tire - flexible but still tough. If you are quick you can press it into shape and then let it cool slowly. Worked great for what I needed, I redid all the bushing blocks:
At this point the original mill was restored:
Next: motorizing it.