Belt or Rack

[bearwen]

I have a question I am looking at building a 4" X 8" cutting area router 8020 or steel I will cut wood, Foam signs commercial types and some aluminum sheet goods thin stock for signs and maybe some aluminum blocks prototype stuff and parts and well I have the design the weights roughlly and the motors etc the big question I have is should I run rack and pinion ala shopbot or should I run a continuose belt system I need speed but accuracy is important within .005" or less.


Bearwen

[ahren]

Both of these are good options for speed and large work envelopes. However, accuracy can be a problem, as rack and pinion can be plagued by backlash, while belts can stretch somewhat. If it weren't for your desire to make aluminum blocks, I would recommend the belt drive system, since you can keep the motors that move your gantry fixed. However, rack and pinion will likely yield a more rigid drive system.

Done carefully, either of these solutions can meet your needs. However, for ruggedness, I would go with the rack and pinion. Spring load the pinion into the rack to get rid of backlash as much as possible, or go with a helical rack (more $$$).

Ahren
www.cncrouterparts.com