On Mon, 2012-04-16 at 21:32 +0200, inflo wrote: > hi, > > servomotors cost much money. i looked at the steppermotor ST4209X1004 > http://de.nanotec.com/schrittmotor_st4209.html (perhaps this site is > also in english available) but has only a torque of 0.15Nm, but a > holding-torque of 17N/cm. > > As Kent said, Taig tabletop mill in CNC form ships with NEMA frame size > 23 stepper motors rated at 200 ozf-in (a bit more than 1.4 > newton-meter) holding torque.So i dont know what torque do i need to > look for? torque or holding torque? or both? and what a good values for > a proxxon mf70 ? > > thanks for help > > flo
You should be able to come up with these spec's yourself. Cut out a wood pulley that can fit to your axis screws. Then wrap with rope with weights on the end. The pulley radius plus the weight it takes to move the axis, and move the axis at your planned rapid should allow you calculate the torques you need. I would convert these values to various common units so you have the numbers handy as you shop. To me, servos are not that expensive. I keep an eye out for motors I can get for free. Maybe for a Tiag class machine, I found a set of DC motors on Shurflo pumps that where discarded because the owner didn't bother to keep them out of the weather. He would just buy another when the pump failed. They needed to be cleaned up a bit and bearings replaced, but bearings are cheap. They are brushed motors, but the average hobby user would have a hard time using a machine enough to wear these motors out. Mesa, Pico Systems and maybe robotics suppliers have PWM input amps that would work well with these. I tend to use US Digital encoder disks and sensors, then make my own housings and hardware. I've also used encoders from printers but it seems they usually don't have an index. Saving on servos is just a matter of how creative you want to get, how much "fun" you want, and not being in a hurry. -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/index.html California, USA ------------------------------------------------------------------------------ For Developers, A Lot Can Happen In A Second. Boundary is the first to Know...and Tell You. Monitor Your Applications in Ultra-Fine Resolution. Try it FREE! http://p.sf.net/sfu/Boundary-d2dvs2 _______________________________________________ Emc-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-developers
