first post can the rack an pinion be used to drive x axis rather than screw on lathe

[ken ben]

is this good or bad lots of backlash on rack

[wildwestpat]

Hi Ken

The answere is yes but there are a lot of disadvatages!

1. The gearing is all wrong to get a supper smooth finishing cut. The pinion is sized on the normal lathe apron to give rapid movement (traverse) under hand wheel control. The lead screw can drive at slow speed and hence get a smooth finish as the cutting edge overlaps at each sucessive revolution.

2. The turning of the chucked object and the advance of the tool need to be synchronised accurately for screw cutting operations.

3. Yes there will be a lot of backlash but that is secondary to the above two points.

4. This could be made to work with a fine toothed rack and a small pinion combined with an accurate DRO and some cute software manipulation.

Hope this helps crystalise your thoughts.

[BillTodd]

1. The gearing is all wrong to get a supper smooth finishing cut.

Not strictly true, my Hardinge HLV-H uses the rack and pinion (driven by an electric motor via a clutch and gears) - super smooth finishes are normal.

The biggest issue for cnc operation is the backlash - It'll be difficult to remove unless you can fit a pair of pinions and have a pair of motors (one driving one way one the other).

[ken ben]

thanks for the info