I have a motor with a 5mm shaft. I want to attach a gear to it, but should I pick one with 5mm bore, or does it have to be wider for some reason? I find lots of gears with a bore of 6mm and only few with a bore of 5 mm so it would be easier to get one with a 6mm bore.
Also I found this site which uses a “MOD” system to tell if one gear will fit into a different gear. But there are also other sites that use this MOD system. Is it “universal”? Will a MOD 1 gear from the site I mentioned fit a MOD 1 gear from eBay?