On Monday 16 January 2017 12:46:03 Jon Elson wrote: > On 01/16/2017 09:01 AM, Gene Heskett wrote: > > I had a dial sitting on the saddle watching X motion, and > > put it in the range where it was at zero on the outer end when it > > had run to completion and parked itself. Then I ran it again, and at > > the end of the 2nd run, it was parked 0.041" inward from where it > > was parked the first time. This difference does not show in the dro > > display. > > Whose stepper drivers are you using, and do they have > opto-isolated step and dir inputs? > If so, then make sure whatever common there is for the step > and dir inputs are wired to the controller board by a direct > wire that goes to no other system. One giant common ground > for logic and power sounds like it might work, but my > experience is it DOES NOT. > > We've had problems with my PWM system when a common ground > is used. It causes ultrasonic oscillations where the power > transistors switching cause pulses on the common for the PWM > command and that becomes a feedback loop. > > The fix was to have the PWM and DIR common wired back to the > ground terminal on the controller by a direct wire, and then > another wire from the controller ground to the system > ground. You might have a similar situation. If your drives > don't have opto-isolated inputs, then all I can say is "good > luck!" > > Jon
They do Jon, I don't think in Chinese stuff suitable for nema23 and nema34/42 motors that you can buy them any other way. Nema 23's need a 2M542 or a M542T, which at first glance look like carbon copies, but aren't quite. The X motor is an 8 wire motor, wired parallel, but its still being a speed problem, so I think I'll look around tonight and see if I can find a single shaft 425oz in 8 wire, this one has a tail shaft and the tall shaft will have to go to make room for the triple stack 425 or 470 motor. And I found & made another pass at fixing the slippage, it wasn't noise from kits own stepper. The green threadlocker had let go, so it was very slowly walking out of the taperlock socket in the back face of the thrust bearing I had made. Then when I put it back together, I didn't get perfect concentricity between the drive shaft and the screw, and was forced to put a prybar in the works to either bend it straighter, then found (I'd had a heck of a time determining the center height of my new nut holder, there wasn't enough of the old nut to measure) and once the screw was running straight, found I need about 20 thou more top on the cage, so now it has a thin, hard washer intended to be part of a thrust bearing I'd had sense enough to buy spares of when I bought them, between the bottom of the cross slide and the top of my nut cage. These ball nuts have no mounting facilities, so I had to make a cage, which because they also had no wipers, now have some brass squares with a cone shaped pocket to hold a felt ring cut from an old hat, which when one end is driven towards the other until they have a death grip on the nut, are also doing the felt compression to wipe the nut clean and wipe it with oil at the same time. With a pipe wrench on the 40 tooth pulley on the end of the shaft, and a 5/8" wrench on the homemade taperlock, which is 3 or 4 times tighter than the first time I put it together, and the taperlock given a few more drops of green threadlocker, It might stay fixed for while. I just ran the lathe pawn, cutting air, 4 times and the x resting point when the spindle shut down was +- less than a thou on the dial. Every time. So thats encouraging. But I've a question or 2 for Peter, so I'll be back after I've rounded up a nose bag at Subway. 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-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-developers
