Rack and Pinion

Hi
Could anyone give me some pro's and cons with using rack and pinion?
The machine I'm planning will be about 700mm x 1000mm used for cutting plastics.
Also which type would you suggest?
Cheers
Patrick

Pro's - potentially very high feedrate. Accuracy not as good as a ballscrew. For the size you need I think ballscrews would be better with two on X and one on Y. It depends what federate you need?

If you are only using it for plastics and not high cutting forces then using timing belts could be acceptable, and cheaper.

Using ( Helical ) angled teeth on the rack and pinion help to increase accuracy. The machine will also run smoother compaired to standard gearing. We use Helical rack and pinion on our Laser and its accurate to 0.1mm. You will need a tensioning device to keep the pinion correctly set into mesh with the rack, too tight causes additional wear and tear and extra load on the drive system and too slack causes backlash. As with all drive systems they need to be kept clean and lubricated. I normally use a dry lub to prevent stuff sticking to the rack or pinion which would then be ground into the teeth preventing them from meshing correctly.

Regards

Ian

Thanks for the info guys, I will get back to you once I've made up my mind what I'm doing (which could take a while)
Cheers
Patrick