Second CNC table build, here we go again....

[Davek0974]

Backlash is the slop or lost motion you can get with rack and pinion drive, normally gears are run with a small clearance between the teeth, when used in motion control you take all the clearance out by spring-loading the pinion against the rack so there is no clearance at all, this works well until the pinion or rack wears and backlash comes back. This will cause steps in the cut finish where the direction changes or circles to come out not quite round etc, basically its a bad thing.

Ballscrews can have anti-backlash nuts fitted which are two nuts with tension between them.

Cost for a 1.4m 20mm screw with end bearings and nut in the UK is about £350-£400, length is also limited.