[CNC] Delrin Bushings For Cnc Ball Screw Shaft

[davidh]

I'm currently building a cnc gantry and assembly for use as router, or gasket cutter or whatever, and its getting heavy. . . over engineered by me. i have made Delrin bushings for the ballscrew shafts, instead of ball bearings, and need an opinion or two about how these will or won't work, and what should the bore tolerance be in relation to the ballscrew shaft itself ?
my first guess was to just make it so the shaft will rotate unimpeded, so i made the bushings except for the bores.
the thrust of the ballscrews i hope will be restrained by a delrin washersand steel set collar on each end of the shaft.
is this a good or bad idea ?
I'm using 400 inch lb servos, and aluminum flex joints to coupling them to the ball screws

 

[JimDawson]

I think you'll be OK with a fair amount of radial play, but the axial play will effect the accuracy. It should be zero clearance, installing some thrust bearings along with a nut to tension the assembly might be a good idea. Something like this http://www.vxb.com/page/bearings/PROD/Thrust/Kit8671