On Thursday 06 December 2012 19:50:33 Michael Haberler did opine: > sorry for what maybe sounds like a dumb question, but having read the > Proctor/Shackleford paper on the influence of jitter on steppers which > basically say: "all it causes is a loss of torque on the order of 10%" > (given the figures at the time the paper was written), In view of my experiences at least I would tend to take any such claims with a 10 lb bag of salt. I wouldn't make a blanket statement that they are full of it, but spread on an Iowa cornfield, it can't help but raise the yield a bit.
> also, having never seen a stepper stall myself except when banging into > a limit: > > Am 06.12.2012 um 20:47 schrieb Gene Heskett: > > On Thursday 06 December 2012 14:38:54 Michael Haberler did opine: > >> Gene, > >> > >> just curious on your method: > >> > >> Am 06.12.2012 um 17:14 schrieb Gene Heskett: > >>> Chuckle.. NP Kent, but I would point out that it only takes one > >>> out-lier of an extra 50 u-s, in a 25 u-s loop, to cause a stepper > >>> stall and a wrecked part or tool. To me I could care less if its 2 > >>> u-s or 7 u-s because they aren't show stoppers. But that 2x a day > >>> 50 u-s lag IS a show stopper because that is the puppy that will > >>> cheerfully eat your lunch. > >> > >> How did you determine a) the stepper stalled (for how many steps?) > >> and b) actually the cause was the delay you mention? > >> > >> - Michael > > > > If a stepper stalls, running above 1/3 its max speed, and does it at > > random times, that is the doorstep I lay the blame on. Its also the point where I may add 1 or 2 microseconds to the base_thread before I restart. There is of course a point of diminishing returns there because the available step rates then must have a coarser value, resulting in a noticeably less smoother speed variation. For tolerably smooth control those steps should be only 5% or so up or down. > Do you have any hard evidence for that, or is that pure conjecture? I suppose it could be called conjecture, but I've had the latency overrun advisor come up at at the same time too often for it to be just a co-inky- dunce as one friend of mine was fond of saying. > How do you discriminate that suggested cause against mechanical > overload? If the machine is 'cutting air', I think its not likely to be mechanical. I do run the machine by hand to check on binding if I adjust any of its ways. Cheers Michael, Gene -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) My web page: <http://coyoteden.dyndns-free.com:85/gene> is up! "Of all the tyrannies that affect mankind, tyranny in religion is the worst." -- Thomas Paine I was taught to respect my elders, but its getting harder and harder to find any... ------------------------------------------------------------------------------ LogMeIn Rescue: Anywhere, Anytime Remote support for IT. Free Trial Remotely access PCs and mobile devices and provide instant support Improve your efficiency, and focus on delivering more value-add services Discover what IT Professionals Know. Rescue delivers http://p.sf.net/sfu/logmein_12329d2d _______________________________________________ Emc-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-developers
