On Thu, 11 Mar 2010 06:33:36 -0600, you wrote: > >I don't remember the details but remember a size 34 stepper on the bench >here running somewhat above 3k rpm. It required low accel but you could >control it getting up to speed. Motor inertia made it really difficult >to slow down while maintaining position -- impossible to do any useful >work with it. The torque curve on steppers drops off quickly as you >turn them faster. Position feedback doesn't help much.
A stepper running on a bench driving no load is not a particularly representative test. Without any load they are very difficult to control accurately. As you say they will go fast - I've run them at 5k rpm on the bench to test breakout board opto speed. He's a post from Mariss (geckodrive) >Back when I was younger and more foolish, I once ran a step motor to 127,000 >RPM. It was a NEMA-23 Portescap Disk Stepper; the rotor was a ceramic magnet >disc with cantilevered coils, kind of like a disk type servomotor. > >The motor exploded on the test bench at 127,400 RPM but luckily the motor case >contained the debris, the rotor being reduced to ceramic sand. > >A little bit of calculation (2" diameter rotor disk, 127,000 RPM) gave a >tangential velocity of 1,100 feet per second at the circumference. 1,100 fps >is an interesting number, it is the speed of sound at sea level. > >I have liked to think I took a step motor supersonic and shock waves destroyed >the motor. More likely it was centripetal forces but it's fun to think Mach1 >(not Mach3) effects did it in. > >Mariss My router on testing will rapid 8m/min reliably and accurately, the triple stack Nema 23 steppers are direct driving 4mm pitch ballscrews, so I reckon that's 2000 rpm. That's on 75V at 2.5A. To be fair though, I don't run that fast normally, I've set rapids to 6m/min, kinder on the machine, it doesn't try and jump around the floor at those speeds :) At 37.5V 2.5A it will only do 4.2m/min or so before it becomes unreliable. Steve Blackmore -- ------------------------------------------------------------------------------ Download Intel® Parallel Studio Eval Try the new software tools for yourself. Speed compiling, find bugs proactively, and fine-tune applications for parallel performance. See why Intel Parallel Studio got high marks during beta. http://p.sf.net/sfu/intel-sw-dev _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
