Help with settings!

[Tenson]

25KHz is working fine now I have the dip switches sorted. Also the motors are less hot since I enabled half current SW4.

However there is ANOTHER issue! All axis move nicely except the side-to-side one (Mach 3 calls this X). Strangely it goes in one direction (to the right in the video) fine and in the other it makes a horrible rubbing noise. It's the ballscrew, but I don't get exactly what the issue is. Can anyone help?

It is running with a rotating ball-nut arrangement, so the ballscrew is tensioned between the gantry sides. I've played with alignment of the ballscrew and even thought it seems to be straight and central with the ballnut it always makes that sound. The only way I can get it not to make the noise is if I press the left end downwards (as it moves towards it), but as the gantry moves to that side it automatically pulls it back up again to be aligned with the ballnut, so it it only works one time, I can't fix it like that. Interestingly the problem reduces massively if I fix the ballscrew at the right end only, or hold it softly by hand, but I worry this might not be very accurate. Actually the ballscrew is not straight, but when tensioned and aligned it is, not that this makes it work well.

I guess it is some problem with the moment force in that direction but how I'm supposed to cure it, I've no idea; just the that end hang freely so it can bob up and down?

Video 1 - Ballscrew tensioned tightly and straight.
DSCF8166.mp4 video by tenson_uk - Photobucket

Video 2 - Ballscrew held at one end only by hand.
http://s608.photobucket.com/albums/t...t=DSCF8168.mp4