Re: EMC and lead screw compensation

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Wally replies:

>Smokie, I could not tell if you were kidding or serious in your
>reply. If you have acme screws and try to circle interpolate a
>circle you get a axis jump at 4 points of the circle from the
>backlash. It is very doubtful this big jump could be compensated
>for as the stepper would have to reverse direction faster than the
>table would jump.

One way to avoid this problem would be to generate full arcs in 4 quadrants
so the control will read a new block at each compass point and compensate
for backlash before executing the next quadrant. This method works very well
on the Ahha software, I do not know about the other software packages
discussed in this forum.

While this is not a replacement for quality ballscrews and a system with
ZERO backlash, it is better than having to live with no backlash
compensation for arc moves in a low cost system.

>You Can't make a silk purse out of a sows ear.
>Bridgeport's typically have about .03 backlash.

This is true!

>Also to put a laser and associated measuring equipment on each axis
>would probably cost much more than the ballscrews would.

Agreed!

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