Thanks. Have to investigate those G codes in more depth. John
> -----Original Message----- > From: Gene Heskett [mailto:ghesk...@shentel.net] > Sent: January-01-18 6:19 PM > To: emc-users@lists.sourceforge.net > Subject: Re: [Emc-users] 240V single phase input vfd > > On Monday 01 January 2018 18:59:08 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? > > > > Thanks > > John > > > All thats needed is a reliable way to track the spindle as it turns. > > From that and the 1/tpi or tpmm of the tap, the rest of the required > motion to carry the tap into the hole in synch with the taps own > threads, and a reversable spindle to back the tap out of the hole, > totally in synch with the taps own threads. This is G33.1 at work. > > Switching from a tap to a single tooth, usually triangular cutter, (using > G76) will drive the cutter at the desired number of threads per unit of > travel again to cut the thread, retracting the cutter over a programable > distance at the end of the thread, or drive the tool into the thread at > the beginning of the cut or both. Here the spindle synch is disconnected > at the end of the cut, the tool is taken back to a point about 1 turn > away from the start of the thread, and synchronized motion is > re-established at the next index pulse from the encoder on the spindle. > Here also, the tool is driven at 29.5 to 30 degrees as its driven into > thread so that the cutting action is only on the leading edge of the > tool, much cleaner cut. > > G76 has the concept of a drive line, which can be adjusted for increased > clearance during the tools retrace move, this and the length of the > extraction move can be exploited to make tapered threads with very low > taper angles. That in turn can make an extremely high pressure > compression joint for attaching a extended drive shaft to the end of a > ball screw. > > > Both of those 2 gcodes need carefull study. They can be very powerfull > when used correctly. > > > > > > > > > > > > ---------------------------------------------------------------------- > >-------- 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 > > Emc-users@lists.sourceforge.net > > 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) > Genes Web page <http://geneslinuxbox.net:6309/gene> > > ---------------------------------------------------------------------------- -- > 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 > Emc-users@lists.sourceforge.net > 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 Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
