On Saturday, February 21, 2015 10:29:56 AM Peter C. Wallace wrote: > On Sun, 22 Feb 2015, Erik Christiansen wrote: > > snip > > > On a 3D printer, free of cutting forces, I figure microstepping would > > be OK at constant velocity, but rubbery under strong acceleration. > > At least it's only full steps that you can permanently lose. > > Actually step motors lose steps in multiples of 4 full steps > (a full pole slip = 360 electrical degrees, a full step is 90 > electrical degrees) > > > Peter Wallace > Mesa Electronics
Thanks for pointing that out Peter, and keeping me honest. It's one of the details that slipped my mind in my earlier expounding on it. On the usual 200 steps/rev motor, thats 7.2 degrees, and a part wrecking error, even on a 20 tpi acme leadscrew in one of the toy tabletoppers. Most such slippage is at or near the top speed, which results in an outright stall, so the machine has to be recalibrated to its home switches anyway. I could see it happening at motion startup, but that would likely be such a nuisance the user would soon find the missing decimal point in his 4, or 5 digit accel setting in the .ini files accel settings. 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> ------------------------------------------------------------------------------ Download BIRT iHub F-Type - The Free Enterprise-Grade BIRT Server from Actuate! Instantly Supercharge Your Business Reports and Dashboards with Interactivity, Sharing, Native Excel Exports, App Integration & more Get technology previously reserved for billion-dollar corporations, FREE http://pubads.g.doubleclick.net/gampad/clk?id=190641631&iu=/4140/ostg.clktrk _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
