Gene wrote: >Looking at the torque curves of the SDSK series, and the steady state >available powers, for a spindle drive the steady state limit is the >important one, and its much lower than its peak torque while moving to a >fixed position. You have to get large and ex$pen$ive to get steady state >above 250 oz/in at a usable rpm. You may want to check out the MC >series which are brushless servos internally. I'd have to assume they >also would overheat in a steady state run at a given load. You can only >pack so much horsepower in that volume before something gets too hot.
Andy wrote: >Choose one with the same peak torque as the stepper that people are >using, and you get the same as they have at low speed, and useful top >speed. >You still need to trade-off peak torque for spindle speed, but the >Clearpath motors do look useful. >However, the Clearpath motors that make 1800 oz.in don't go faster >than steppers. But then 1800 oz-in is 12Nm, which is lots, possibly >rather more than necessary. First off, what it's competing with, from: http://sherline.com/product/33050-dc-motor-speed-control-units/ under the "specifications" tab 90 VDC motor .06 KW (60 W) at 10 oz. in. / 6100 rpm Duty rating: Continuous-10 oz. in. at 6100 rpm, .85 amperes; Intermittent-30 oz. in. at 5500 rpm, 1.75 amperes (5 minutes on / 15 minutes off). I'm guessing that the 30 oz. in is the highest (intermittent) torque in the entire speed range. The torque at the spindle is increased by speed reducing pulleys 6100 motor rpm = 2800 spindle rpm. I first saw Tecnik Clearpath servos many months ago and thought they were DC motors with encoders, and why swap one DC motor for one the same size or smaller? I've since realized that all of them, both SD and MC are brushless motors internally. Nevertheless, I imagine they do run hot given the large heatsinks on the back and the provision for adding a fan. It's very difficult (for me, at least) to compare a stepper motor to one of these because the torque of a stepper is going to fall off rapidly with speed. The stepper used is so huge, however, how much torque will it lose between zero and (say) 1500 rpm? Martin ________________________________ ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
