On Thursday 17 December 2015 10:40:41 Viesturs Lācis wrote: > AFAIK it has been few years since Araisrobo and Yishin Li have done > it; take a look here: > https://github.com/araisrobo/linuxcnc/blob/master/src/emc/kinematics/t >p.c > > I found some threads from 2012 on developers mailing list, where > Yishin discussed their work on that. This one seems even older, > hopefully it would get you started on finding some more useful > information: > http://sourceforge.net/p/emc/mailman/message/27376772/ > IIRC it has not been implemented in LinuxCNC, because it would not > work for spindle-synchronised moves, but I might be totally wrong on > that :)) > > > Viesturs
Early on, in playing with G76, I found that the actual lockup phase relationship was quite spindle-speed dependent, wrecking a few threads because I thought I could crank the speed up once the motion was verified. And was advised that this was the Z accel lag, and that as long as the spindle speed was maintained, it would not be a problem. Doing that, it hasn't been but I now restrict the spindle rpms to <300 also. I assume the same caveat applies to G33.1, rigid tapping, so I don't crank the revs up there either. But I have wondered why, in the grand scheme of things, that delay, which can be obtained in degrees without a huge hassle, is not turned into a pre-start, that based on the rpms, puts the actual start z point that fraction of a turn ahead of the index, which would result in the lock being obtained such that the index to spindle phase was within an encoder count (or closer) of zero. Doing this on every Z restart would allow us to run it one or two cycles at 50 rpms to check clearances etc, then crank the spindle up to 500 revs and get the job done, without wrecking the threads cut because the phase lag is a fixed time at that rpm. Obviously it would need stretching because of the higer speed Z needs to accelerate to at a higher spindle rpm. I haven't tested recently, perhaps this is something that Robert Ellenburg has addressed? Call me "Curious". Thanks. 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) Some mill pix are at: Genes Web page <http://geneslinuxbox.net:6309/gene/GO704-pix> ------------------------------------------------------------------------------ _______________________________________________ Emc-developers mailing list Emc-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-developers
