Driving floating end (ballscrew)

ok iv just run some tests on the coupler... with 10N it compresses by .43mm im assuming simmilar under tension
the full travel of the coupler is just over 1mm fully compressed
im thinking unless i take a blow torch to the ballscrew (y axis) i should be ok

if not it should run long enough to machine myself out of trouble

i thought id designed this machine to perfection :) however... i snapped up some cheap 20mm profile rails for the Z axis instead of the 15mm in the design and its had more of a knock on effect than i exspected :(

iv got this funny feeling ill be seeing a few more of those before im done :)

I guess you could always loosen and re-tighten the grub screws between the coupler and the ballscrew twice a year to take out any stress. Or you could mount the stepper on a sliding arrangement so that rotations were prevented but it could slide back and forth 0.5mm or so.

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Originally Posted by routercnc

Or you could mount the stepper on a sliding arrangement so that rotations were prevented but it could slide back and forth 0.5mm or so.

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Maybe put a rubber O-ring on each of the 4 bolts that mount the stepper motor. I did that on my rotary table to compensate for a little radial misalignment and it works fine.
It could also damp vibrations...

It'll work - just do it.

If all these MDF, draw slides, all thread screw jobbies work what's the problem.

Never let the decimal point stand in your way.

you can get rubber mounts for steppers, that simply mount between the stepper and the frame, giving a slightly flexible yet resilient mount.

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Originally Posted by Jonathan

Maybe put a rubber O-ring on each of the 4 bolts that mount the stepper motor. I did that on my rotary table to compensate for a little radial misalignment and it works fine.
It could also damp vibrations...

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Oldham couplings were designed to take out radial misalignment, Those lovejoy couplings are a total waste of time and space for CNC machines, they are better off driving sewerage pumps.

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Originally Posted by John S

Oldham couplings were designed to take out radial misalignment...

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Yes I know...didn't have time to make an Oldham coupling at the time for the rotary table and haven't bothered since because it works fine. It's only a very very slight misalignment.