On Wednesday 04 April 2018 12:33:26 Jon Elson wrote: > On 04/03/2018 11:50 PM, Chris Albertson wrote: > > Yes the faster you go the bigger the jumps. With my 1MHz clock I > > can only make pulses with periods that are a whole number of > > microseconds. > > > > So I ask again: What is the fastest step rate you actually use with > > a real machine? > > It TOTALLY depends! There are guys running delta 3D > printers with NEMA 17 motors that probably go to insane > RPMs, and thus really high step rates with microstepping > drives. > > > What is needed? Do people run motors at 100,000 steps per second? > > 100K (micro) steps/sec is 10K full steps/sec with a Gecko > driver. 10K full steps/sec with a standard 1.8 degree motor > is 50 RPS or 3000 RPM, so that is quite possible with a good > driver and NEMA 17 motor. > And I have made 3300 revs on a nema 23, 45 volts into a 2m542 driver. No usable torque, but it ran. I don't recall the step divisor ATM but it was not less than a /8.
> > What I'm guessing is that it is rare to run as high as 10K steps per > > second. I could be wrong, so I'm wanting to hear from people who > > are running real machines. > > 10K (micro) steps/second would be 5 RPM or 600 RPM, VERY > normal speeds even with much larger motors. If you > direct-drive a 5 TPI screw at 600 RPM, you get 120 IPM, > which is quite normal. Absolutely. > So, 10K steps/sec is NOT at all rare when using > microstepping drives. > > > To say this using MK or LinixCNC terminology what is the fastest > > usable "base rate"? I am using a 1 uS (or 1MHz) base rate. Is > > that fast enough? IMO, no. Mesa's cards use a higher frequency, in some cases I think 50 MHZ, (or is that only for encoder sampling) so the timing jitters even when its doing a semi-random step to generate an in between pulse train, the timeing errors are under 1%. > With Machinekit on the Beagle Bone, the PRU can generate > steps a lot faster than X86 software stepping, and there is > no base thread. I don't know the max rate you can get, but > you can certainly get step rates well into the 10's of KHz, > while doing other stuff, too. > > Jon -- Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Genes Web page <http://geneslinuxbox.net:6309/gene> ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
