Re: Designing CNC router for PCB milling
I've been reading a lot of forum posts from people buying ball screws and linear rails on ebay. It seems all the THK and NSK stuff is fake, even if it's stamped with the manufacturer's logo. Apparently this is a pretty big counterfeit market. That said, people feel the quality they are getting is pretty good and it's a great value for the price. But it's a bit of a crap shoot, sometimes you get a dud. I think if you go the ebay route you should be prepared place an duplicate order if it doesn't work out the first time. I'm not sure how returns work with most of these guys; it seems returning something to China would be a pain. The chances of getting a dud appear to be on the low side though, most people seem pretty satisfied with their purchase. I don't know anything about getting servo motors or steppers on ebay. I suspect it's a similar situation. Since these prices are so cheap, it's still a good way to go. I do expect I'll be getting some, maybe all, of my stuff on ebay, but I won't be ready for purchasing for a while - I still have all the designing to do.
Regarding the spindle, there are a couple ways to go. First is get an integrated using where the spindle and motor are one unit. Second, have the motor be separate then you can use a belt drive and increase the speed. This is how the Othermill works. I'm not sure what the issues are with a belt-pulley setup are at high speeds like 60k RPM. The Othermill doesn't go that fast, only 16.5k RPM. I'd prefer an integrated unit, but I'm open to either.
"You can't teach stuff in a school that you would learn in real life unless the real life people are in charge of the school." - Gene Sherman