Quote Originally Posted by Voicecoil View Post
I'll agree 100% about the HGR20's being a little sticky, but I'd rather they were that way and had no play, than "free and easy" and wobbling all over the place. If you can turn the ball screw end shafts smoothly between finger and thumb then I guess it should be OK - after all, a decent stepper should be giving a good few hundred Ncm torque.
Thanks for confirming my thoughts about the HGR20s. I think I've got the rails sorted, its the ballscrew causing issues I think. I have got it to a much improved state, but I can't quite "turn the ball screw end shafts smoothly between finger and thumb". Whilst the resistance along the entire travel is now pretty much uniform, there is a little patchiness to the motion - there are occasional slight sticking points which require a bit more force than just two fingers can apply. I mainly test it using the belt to move the ball screw and it all operates ok in motion though from a standing start it can be a little "sticky".

It may well be fine with the reasonably overpowered servos I will be using. I'm going to leave it as is and proceed with the other axes so I can compare the motions between each axis.

If its still a problem I can think of only 2 ways forward:
- widen some of the mounting holes so the major extrusions have a little more "wiggle room" so I have broader alignment range
- buy a new ballscrew - I worry I may have subtly bent this one during my initial tests and now it will bind whatever I do...