> On 20 Mar 2020, at 3:41 pm, John Dammeyer <jo...@autoartisans.com> wrote: > > > >> -----Original Message----- >> From: Phill C [mailto:phillcarte...@gmail.com] >> Sent: March-19-20 9:36 PM >> To: linuxcnc-users >> Subject: Re: [Emc-users] A hal question? >> >> >> >>> On 20 Mar 2020, at 3:24 pm, John Dammeyer <jo...@autoartisans.com> >> 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. >> >> I would assume that Z is �coupled" to the output of the spindle encoder and >> that the count is reset at each index >> <http://linuxcnc.org/docs/html/man/man9/encoder.9.html >> <http://linuxcnc.org/docs/html/man/man9/encoder.9.html>> >> > This link is broken and Jon just mentioned that the index is only used once > at the start of tracked motion.
Well, it works for me. Try googling linuxcnc man encoder _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
