Gathering ideas for a new CNC router-mill thingy

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Originally Posted by JAZZCNC

Dave Think you have been got by Classic Gotcha.?
How are you going to access the holes for fastening the rear plate to the bottom bearing plate.? The Z bearings fasten from back side so can't fit when rear plate is fastened. You'll need to Lift the bearings so can access the bolts.

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....Scurries off to grab the drawings............

Ok, it definitely seems to work for me :courage:

Attachment 17634Attachment 17635

Assembly would be to screw the x axis support plates on at the bottom and middle positions, then there is just enough clearance to pass the screws from the back to the front to mount the Z axis carriages, bottom line is tight but room should be ok.

:courage:

Build log started here...

http://www.mycncuk.com/threads/9577-...7182#post77182

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??

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Originally Posted by Davek0974

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.)

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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.

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Originally Posted by Davek0974

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

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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.

ok thanks, will leave nuts on screws.

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

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??