Gathering ideas for a new CNC router-mill thingy

[Davek0974]

Ballscrews

Never used these before, the motion stuff arrived today :)

Questions...

Is it normal for the BK/BF end support bearings to be a press-fit? (Don't want to go forcing and break something.)

Do the nuts have to remain fitted or can they be removed without losing all the balls??

[JAZZCNC]

Questions...

Is it normal for the BK/BF end support bearings to be a press-fit? (Don't want to go forcing and break something.)

Do you mean they are Stiff to get on screws.? Or the bearings are pressed into the BK block.? If just stiff to get on screws then yes this can happen, just give the screw light rub with emery and they'll go on.

Do the nuts have to remain fitted or can they be removed without losing all the balls??

DONT REMOVE the balls WILL fall out. If you want to remove the Nut then you need tube the same size as the minor diameter of the screw and then rotate the nut onto it.

[Davek0974]

ok thanks, will leave nuts on screws.

I was surprised how big/heavy the spindle is :)

[Davek0974]

Ballscrew alignment...

How good does it need to be?

Obviously the simple answer is "perfect" but, how many here can honestly say their ballscrew / nut / motion system is perfectly aligned??

So, what sort of tolerance is there, clearly if its way out then the nuts will bind, motion will lose steps and things will fail quickly but if only a little off of perfect?

When assembling my new build i have the rails on one side of a 45x90 beam and the screws on the other side, I aligned the rails and BK/BF blocks carefully with a vernier to the same reference surface of the beam to within 0.05mm.

However, there is naturally some discrepancy when it comes to tightening the nut mounting blocks down to the travel system, I have used some shims to get shaft deflection as close as possible to zero when tightening them down.

Or is it better to float the BK/BF blocks and then clamp the nuts, wind the travel to each end and tighten the BK/BF's up then??