Rotary Table CNCing

[ptjw7uk]

Irving,
You reminded me, I had to fit a sintered bush inside the offset bush as the thrust I used inside was a needle and so did not provide for any side thrust as ball units do. It is not easy to assemble due to the offset arrangement but at least it works as long as I dont try to reduce backlash to much.

Peter

[irving2008]

Irving,
You reminded me, I had to fit a sintered bush inside the offset bush as the thrust I used inside was a needle and so did not provide for any side thrust as ball units do. It is not easy to assemble due to the offset arrangement but at least it works as long as I dont try to reduce backlash to much.

Peter

Peter, can you explain further. I was looking at sintered bushes with a view to taking a .375" ID .6" OD bush, opening out to 10mmID and turning it down to 15mm OD. It will have less friction than cast-iron to cast-iron. But as I said above, the torque requirement at the moment seems to be OK with a 1Nm motor so maybe I'll leave that till later if needed. The end-float I can set now with a 1.5thou feeler gauge and the motion feels smooth. The worm is a 2mm pitch approx so, if my calcs are right, this represents an additional 5 or 6 minutes of backlash on top of the 15minutes already present and this can be taken up by the software

[Robin Hewitt]

I was looking at sintered bushes with a view to taking a .375" ID .6" OD bush, opening out to 10mmID and turning it down to 15mm OD.

Sintered bushes come oversize and go to size when you drive them home. I did try machining one once and it was distinctly odd, they are a bugger to chuck and smear rather than cut