On Wednesday 15 July 2020 07:40:50 Gene Heskett wrote: > On Wednesday 15 July 2020 00:58:43 Gregg Eshelman via Emc-users wrote: > > There are sine wave controllers that do various smoothing things to > > run steppers smooth and silent. Trinamic calls it Spread Cycle and > > Stealth Chop. https://www.youtube.com/watch?v=Q0sJlGh9WNY On > > Tuesday, July 14, 2020, 11:18:22 AM MDT, Todd Zuercher > > <to...@pgrahamdunn.com> wrote: > > > > If you can hear it, it isn't smooth. I'd recommend using the > > finest micro stepping setting your driver offers, but simply not > > counting on more than 1/4 of a full step in your resolution > > accuracy. But just because the motor and drive may not be able to > > physically achieve positioning accuracy much better than 1/4 step, > > doesn't mean that having the finer micro step resolution won't > > significantly contribute to smoother quieter motion. > > I would tend to agree with this, except for the slewing. There. using > a microstepping of more than 16 will run out of bandwidth in the > dm542's opto's and he may get stalls, which will require rehomeing on > polaris again before it knows where its at. So there it might be > advantageos to use pulse lengths that would set an overall clocking > limit below 200 kilohertz. > > Been there, done that on my machinery. A dm542 can turn a much bigger > motor just laying on the table at just above 3000 revs, but when it > stalls, its so sudden it jumps up in the air about an inch. But with > the divisor set at 16 or more, I lost speed at 32 and was slower yet > at 64. > > So most of my stuff is running on /8, which seems to be a good > compromise between speed and noise. The dm542 is a decent driver, I'm > running 9 of them here, 2 on TLM, 4 on the 6040, and 3 of them on the > GO704. Software stepping, as opposed to a mesa card, will limit slew > rates because the step rates are limited by base thread speeds and the > next increment faster is something the motor can't accel to in one > step so it stalls. And it was doing that on the little hf mill at > speeds it could cut at! > > So eventually a Mesa 5i25 found a home in that machine, at which point > I thought the psu voltage was the limit. That whole kit, computer and > all, is now runniing the 6040 at 200ipm rapids. The diff is the > smaller, lower inductance motors. The one thing they did right on the > 6040. The rest of the electronics was BBLB stuff and not capable of > even being interfaced with linuxcnc. The vfd started the spindle ok, > but in random directions I couldn't control, so the usual clone vfd > from ebay now does exactly what linuxcnc tells it to. > > What I am interested in is the stellarium interface, that seems to be > an extra cost option from a different source. My googling has not > found it for sale or even a price quote, but then my goggle-foo has > been found wanting before. I have a 10" Meade newtonian thats now been > standing face down behind the back door for about 20 years. I've also > the motorized pier mount. But I'm down in a cul-de-sac and can just > barely get down to polaris due to the tree line on the hill to the > north. And a huge 60+ yo maple I don't own blocks much of the below > equatorial southern sky view. I should make it a building as I'd like > to do frame a week movie of eta-carinae, probably the next supernova > we'll get to see. I also have a lack of dark sky problem, street > lights are old and unshielded. Sigh... But that interface interests me > greatly. > Better google-fu, found several sw packages that work with stellarium, and investigated EQMOD, a freebie DL that looks quite capable. UNK if winderz only. Talks over rs232. Now need schematics for pier control, and there seem to be several such kits available that EQMOD can talk to. All I have is a hand tracking motor and a very simple speed control, teeny little thing, might be able to track for an hour. More research needed to make a proper az/el drive... But first I'm low on caffiene.
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) If we desire respect for the law, we must first make the law respectable. - Louis D. Brandeis Genes Web page <http://geneslinuxbox.net:6309/gene> _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
