On Wed, Dec 1, 2010 at 6:10 PM, Dave Tweed wrote: > M.L. wrote: >> I think the DIY CNC milling crowd routinely does this sort of thing. >> (pertinent advice category) > > Thanks, I thought about that, but don't they generally work with leadscre= ws > that aren't capable of the speed that I need? > > Industrial screw-based stages seem to top out at around 100-200 mm/sec. a= nd > are generally much more hefty than what I need. > > Something like a scaled-up floppy-disk (or optical disk) head positioner,= a > stepper motor with a relatively coarse (multiple-start) screw, could work= .. > I haven't found anything like that so far, though. > It sounds like what you need is basically a giant ink-jet printer mechanism. It's been a couple years since I've taken one apart, but they have a cogged belt, stepper motor, and precise optical encoder. You can probably count steps and do without the optical encoder, but just use a couple microswitches perhaps at the ends and the middle. To get the speed you need, you may have to use a servo motor and rotary encoder. http://www.mcmaster.com/#drive-belts/=3D9ypgg5 http://www.mcmaster.com/#pulleys-for-belts/=3D9ypi25 http://www.probotix.com/stepper_motors Use 80/20 aluminum and you won't have to machine anything. You could even get away with a hardwood frame if the customer doesn't mind that it looks too 19th century. http://www.8020.net/ It sounds like a fun project. If I can help out let me know. --=20 Martin K. --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .