On Friday 20 March 2020 00:24:07 John Dammeyer wrote: > > > But it's here where I become a bit confused. A 60 tooth gear at > > > 1200 RPM produces 7200 edges per second or 1 about every 139 > > > microseconds. Say we're rigid tapping 8 threads which means a > > > total of 57600 pulses. If the hardware counter is 16 bit signed > > > that's larger than the 32767 before the counter rolls over. If > > > it's a 32 bit counter it's not an issue. > > > > I doubt if that would be a problem at 1200 because it would > > following error out from Z not being able to move that fast. > > Probably before the tap ever touched metal going in. Another problem > > would also rear its ugly heard is that the overshoot at the bottom > > of the hole would likely exceed the length of the tap at 1200. I got > > concerned about blind holes, and despite the belts yelping like > > michelin tires on hot blacktop, the overshoot at the bottom of the > > hole was over 3 turns at 300 rpms when swinging an 8" 40 lb chuck > > with a workpiece in it. Trade my 1hp motor for a 10 and a bigger vfd > > might speed up the turnaround but my place isn't wired for that kind > > of power. > > > > So I have modified most of my rigid tap routines to tell me how many > > turns and how far the overshoot is at that taps pitch and show me in > > the gui. So I can cut clear to the bottom of the blind hole w/o > > breaking the tap. > > Hi Gene > I can understand that one has to factor accel and decel into the > picture. The spindle won't stop suddenly and won't start instantly > either. So the Z axis tracks the decelerating spindle and that needs > to be factored into the depth of the hole of course. > > The same is true for threading up to a shoulder. > > I have a spring loaded tap holder so even if there's a little bit of > error my system will ultimately not break the tap. Plus in the near > future my spindle will be step/dir run with an AC servo so > theoretically the tracking of Z verses rotation will be as good as the > system can provide. > > But it doesn't answer my question on how it works with a spindle using > 0-10V plus DIR for the spindle while using STEP/DIR for the Z axis. > How is the Z coupled to the spindle when the control over > deceleration, as you explained about yours, is somewhat loose. > > John > > > > > > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users
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 [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
