Re: Spindle motor drive belts MAXNC 10

Paul Devey wrote:

> Sherline's motors are speced at 3K rpm?
>
> What mods are you performing to get them to run at 7K? Any
> problems with bearings or heat?

Pulley ratios do the trick nicely. Yes, bearings can be tricky. I did,
after about 8 months, finally toss the chinese bearings and installed
some Nachi bearings. I set preload very light and run the spindle in.
Will start out very slow and increase speed until I notice a rapid temp
rise on the head. I back off on the rpm and let it run for several
hours, then start running rpm up until I get another temp rise. I CNC'd
a Sherline for my dad. I had a wild idea to mount the DC motor behind
the Z slide to avoid side loading.
It works great and we use some rather large pulleys to get the belt
around the slide. We've set his up for 10,000 rpm. Took a good while
longer to get this setup to run cool, and we went straight for the Nachi
bearings. Both my dad and I make money with ours. If we have to buy $25
worth of bearings once or twice a year it's no big deal.

Jon