On 21.02.15 09:27, Gene Heskett wrote: > The disadvantages are that they will continuously burn from 25% to 50% of > their running power even if being driven by smart controllers that can > reduce the drive when they have stopped. And the discrete steps they > make, which with smart controlers can be subdivided by microstepping, look > like a prob lem but in the world of flying swarf, not terribly important.
And even burning that power, the torque to hold a 1/16th microstep is only 10% of the full step holding torque, if I caught all of what was said in a LinuxCNC youtube clip I looked at last night. (It was in German, and it's a while since I used mine.) > But unless the current mapping in the controller is exactly matched so > that a 1/8th step is exactly 1/8th step, there will be a cyclic > positioning error. Miniscule, its less than .001" at any point when direct > coupled to a 5mm per rev ball screw. Best match I would guess is when the > motor is being run at exactly its nameplate amperage. With commonly > available stepper drivers having a dip switch current setting that > typically changes in 10 to 15% increments, this isn't as easy to as it > should be. 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. ... > Thanks for reading this far, stay warm guys. We're collecting more white > stuff this morning. There's been an awful lot of it in some states, we hear. Once it's deep enough, mebbe just tunnel through it to the workshop. (I spent an afternoon skiddooing at Whistler, years ago, on 7 meters of snow.) We don't have that stuff here. We just need a way to stop dumb parents from broiling their infants in cars. (see sig) Erik -- Victorian paramedics were called to more than 200 cases of children locked in cars in the first five weeks of 2015. Last year more than 1,100 children were rescued from inside locked cars. - http://www.abc.net.au/news/2015-02-20/toddler-found-dead-kyneton-police-continue-investigations/6158496 ------------------------------------------------------------------------------ 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
