On Sunday 05 April 2020 11:54:08 andy pugh wrote: > On Sun, 5 Apr 2020 at 16:39, Gene Heskett <[email protected]> wrote: > > Is the Z backlash setting used by a g33.1? if it is I might be able > > to play with that and tighten up the thread, > > It might be interesting to log the Z position and spindle angle with > halscope. (It is possible to save the data to file) > > Do consecutive G33.1 moves re-synch to index?
I'd have to assume so. ISTR it didn't start without an index. Both machine now have ATS667 index generators. Interesting possibly is that the ATS667 have pre-edge, such that the 2nd edge is at the actual pole crossing so very close time wise but if the first edge is used fwd/rev is way out of time, probably 15 or more degrees. The ATS667 stays in the state until the tab comes around again and it then resets itself as the slug approaches, then changes state again as the slog scans across the gap between the two hall devices. So the waveform inverts according to the direction. The 2nd edge is the accurate one. However you've said several times that the index is only used to time the start and thrown away after. That makes perfect sense as it removes any direction difference. In the g0704's case there is the gears backlash difference but with the scale ratios as high as they are, I can't believe its part of the problem, perhaps one degree. The same line of reasoning exists for the Sheldon, but that encoders only 240 edges a rev, and maybe under 1.9 degrees. So I'm back to the Z backlash as a possible culprit.. I assume it is applied as the spindle is doing its turnaround. The question then is when, because I am profiling the turnaround so as not to over speed the Z as it tries to keep up. It all happens very quickly but the reverse from motion is blocked until the spindle has virtually stopped at the output of a limit3, whose speed input has been taken to zip, and a one shot measures the A pulse, and when it recovers the reverse is allowed thru to the vfd, the input to the limit3 is restored and the spindle in then taken back to the set speed by the sine-squared ramp from the limit3. What I don't know is when in that state transition, is the backlash move actually applied to Z. IMO it should be the instant the encoder detects that it has detected its turning in the other direction. But I don't know that. And w/o a base thread its not readily seen on a halscope setup. Its too slow. Thanks Andy. 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-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-developers
