Repairing my Makita hand drillI was using my Makita drill when it was relatively cold, when I suddenly heard a loud pop from it, and it started to make funny rattling noises. The drill still seemed to work perfectly fine, oddly enough, but I figured it would be best to finish the job with my other hand drill.
On later examination, it turned out that the plastic fan wheel, which is used to pull air through the motor, had split into three pieces. I'm guessing the press fit of the brass bushing into the plastic fan wheel was a little too tight, and using it under cold temperatures the plastic shrunk more than the brass, and cause it to finally snap.
It wasn't an overly expensive drill, but I really liked this drill, and wanted to fix it. It wasn't really worth ordering parts for it though. So I ended up making a new cross shaped fan for it. Its made of layers of wood in alternating directions, sort of like plywood, but made of maple for extra strength. This I jammed onto the shaft where the brass bushing was before. I drilled the hole just slightly smaller than the part of the shaft it was to go on. Though it didn't take as much force to put on as the original brass bushing, which was so tight on the shaft that I had to cut a slot in it with a dremel tool to get it off.
Anyway, no big deal, but it was kind of a neat repair. Have been using that drill since then without any problems, including for my Horizontal boring jig.
See also: How DC motors and universal motors work