OK gene. I'm all ears 😁. Love To hear how this works. Maybe put the relevant code here.
Regards Andrew On Tue, 27 Apr 2021, 1:37 AM Gene Heskett, <ghesk...@shentel.net> wrote: > On Monday 26 April 2021 08:02:34 andy pugh wrote: > > > On Mon, 26 Apr 2021 at 11:19, andrew beck <andrewbeck0...@gmail.com> > wrote: > > > Still need to automate changing ramp > > > > If you wanted to do it based on commanded spindle speed, then > > "lincurve" would probably work. > > > > Alternatively, you could consider basing it on spindle.0.revs, noting > > that a threading pass is unlikely to get higher than 100 full turns > > between index resets. > > > > Or, maybe even just base it on the spindle running in reverse. I think > > that rigid tapping does a reverse without a stop? > > It does indeed do that Andy, zero smarts about that. And I can't think of > a better way to blow a vfd and/or a 30 amp 240 volt breaker abuseing a > horse or more motor by slamming it into reverse while spinning at its > normal rpms. > > Thats why /all/ of my machines have extra hal code and modules loaded to > control that. I tried to describe the sequence of events that I use to > control that yesterday. It works, and does /not/ trip 15 amp breakers > doing it. My 11" Sheldon lathe, with a vfd but no PID's in the config, > has this hal code in it, and additional hal code to report the > overtravel both in terms of spindle travel in turns, and If the gcode > makes use of it, travel distance of the overtavel provided you tell it > what the tpi of the tap loaded is. > > With a nearly 40 pound 8" 4 jaw chuck mounted, my overtravel is at 100 > rpms, .25 turns, and I can and have done it at 5 second intervals for > half an hour at a time without tripping anything off, and I'm doing it > with a cheap clone vfd that has no breaking resistor hookups, > controlling the vfd thru a pwmgen and a spinx-1. > > Similar hal code is used in the go704 and in tlm but tlm's idea was to > preserve drive parts as none of a 7x12's was ever designed for a motor > that size with millisecond response times. > > The slowdown in the go704 was actually designed to stop the z following > errors at the bottom of a stroke, it can reverse faster than z can keep > up, so the overshoot is still substantial at 1000 rpms. So I tap at 2 or > 3 hundred rpms in low gear. But it also means that if my gcode > accidently outputs an m4 while its turning 3 grand, its back to 3 grand > in reverse in less than 400 milliseconds. Thats a bit hard on the filter > caps, but no great surge from the powerline thanks to Jon's pwm-servo > being a full 4 quadrant control, so it sucks energy out of the spinning > motor as it stops it, running the filters up to around 170 volts, 40 > volts above their rating. but once the motor is stopped, it then uses > that stored energy to re-accelerate the motor in the other direction, so > the overvoltage only exists for less that 50 milliseconds. I usually > hear the iron in the motor chirp from the servo amps programmed 17 amp > limit, which is about 190% of those motors nameplate full load amps of > 9.7, as both motors are 90 volt rated motors getting about 125 to 130 > volts if the going gets tough. > > So it can be done and I'm disappointed that no one is asking me how to do > it. > > 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 > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
