Hi all,

I'm currently building a CNC machine for a friend which is an re-worked version of my own.
For the re-designed spindle, I'm going to use a brushless motor and pulleys.

I know that the likes of T5 and T2.5 pulleys are rated for 500w and 40,000rpm so speed and power isn't an issue.

The issue is how to mount them to the shafts as I have limited tooling For example, the spindle itself has got a 10mm shaft so do I
1. Drill the pulley to 9.9mm using my mini lathe and hope that the runout is enough to make the hole 9.95ish for interference fit
2. Ream the pulley to 10mm and use a grub screw

These options are both troublesome as the spindle is intended for high speed use, about 20,000rpm and the motor for about the same, probably more and I don't really know how grub screws will affect the balance unless I use 2 opposing screws.

Simply put, I would like some words of wisdom on this matter?