Re: Low cost Servo Controller

David Howland wrote:

> Dan (Falck), It seems as though you have a fair amount of experience in the area I am exploring. Others may also have this kind of experience as well. You have run CNC without ballscrews. You said you tried this and upgraded to ballscrews after running without them for a few months. Aside from the cutter sucking the table out of position, as it can in manual milling, was a major part of the NO FUN aspect of working with the backlash, the fact that you had to program in a manner to adjust for it.

There are several reasons that anti-backlash ballscrews are desirable.
1. less friction
allows smaller motors to move machine
2. no backlash
allows shaft encoder to show machine position. High resolution is a LOT cheaper
with a shaft encoder than a linear encoder. Resolution at least 5 x the general user
resolution (ie. .0001") is desirable.
allows heavy climb milling cuts to be performed with confidence.
allows fly cutters and boring bars to be used without the table moving around.
allows circular interpolation to be done without flat spots (no backlash compensation
in software) or jagged bumps near axis reversals (with backlash compensation).
3. Lack of wear, so it STAYS anti-backlash for a long time, whereas acme screws
get increasing backlash in well-traveled areas.

Jon