Rafael, This is an idea on how to provide linear motion to a single axis: http://www.oemdynamics.com/hld_animation/hld_intro.html
The Harmonic Linear Drive (HLD) article was posted in Machine Design on 6/16/08: http://machinedesign.com/ContentItem/719/72741/ScanningforIdeasNovelRecirculatingBeltPowersLinearActuator.aspx The large pulley and small pulley sets are connected together. This provides a speed difference at the outer radius of the pulleys. If the large and small pulleys were the same size then their circumference speed difference would be zero and the carriage would not move. If the smaller pulley had 49 teeth and the large pulley had 50 teeth the pulley edge speeds would be 49 and 50 respectively. This would make the carriage move at a rate of 1-(49/50) = 0.02 or 2% of the rate of the large pulley edge radius speed. I have always been a fan of rotary harmonic drives due to their "near zero backlash" and the example above is just a linear version of it. The linear system provides fast acceleration using low mass components although belt speeds can be high compared to the carriage speed (30-50x faster). If the timing belt in a Honda type R engine can accelerate from 700 RPM to 9000 RPM in 1/2 sec then a properly selected belt should work fine in a linear motion control application. I think the HLD system could work well with a direct drive DC motor because a DC motor can accelerate quickly to 3000 RPM and provide 560" per minute of travel speed with 3" dia pulleys (49 tooth & 50 tooth). My Bridgeport VMC has max travel speeds of 300 IPM. It is far from being state-of-the-art but gives me a baseline for other projects. High quality DC motors with built in encoders can be cheap if you look in the right place. I have quite a few Ametek drive motors from old tape drives that I picked up for $5-10 ea. at a local army surplus store. I'm a sucker for high quality motion control that's nearly free. Dennis ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world http://moblin-contest.org/redirect.php?banner_id=100&url=/ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
