John, To be clear you need either closed loop servos or steppers on all of the motion axis for CNC control. The spindle however can be open loop just as Jon said. A spindle encoder essentially allows all other motion to be electronically geared to the spindle motion. You can run linuxCNC without a spindle encoder but then you cannot do ridged tapping or threading.
John Figie On Mon, Jan 1, 2018 at 6:06 PM, Jon Elson <[email protected]> wrote: > On 01/01/2018 05:59 PM, John Dammeyer wrote: > >> Most of those VFDs appear to be open loop. >> >> What's normally done with LinuxCNC for closed loop spindle control? Say >> you want to do the equivalent of internal threading on a lathe. Is a >> run-out area required or can LinuxCNC control the spindle speed in sync >> with the Z axis so either a tap or cutter follows the threads? >> >> Is an AC Servo (with encoder) even required on a CNC system or just open >> loop variable speed control? >> >> >> I run entirely open-loop, and it works fine. You do need a spindle > encoder for any threading operation. > On my minimill, the spindle slows noticeably when threading, but the Z > axis stays in synch with the spindle, > and it works fine. You need both a "run-in" and "run-out" distance, as > the Z axis cannot start and stop > instantly. > > Jon > > > ------------------------------------------------------------ > ------------------ > Check out the vibrant tech community on one of the world's most > engaging tech sites, Slashdot.org! http://sdm.link/slashdot > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users > ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
