On Monday 26 April 2021 17:37:10 andrew beck wrote: > i have a friend that pulled apart a old 100+ kw vfd and collects caps. > > he has buckets of massive ones > > On Tue, Apr 27, 2021 at 9:02 AM Leonardo Marsaglia > <ldmarsag...@gmail.com> > > wrote: > > From what I could understand gene is using something similar to the > > old KERS used in Formula 1. I don't know if this is a common > > practice because it's really good idea. May be the only drawback is > > the cost of the capacitors and that's why we don't see this approach > > very often. > > KERS is an unk acronym to me. Yes, I do have quite a bank of caps in that psu but the cost was zip, came from an old employee I was told to fire 30 years ago, but his building skills were very useful when my door had a nameplate with Chief Engineer on it. I refused, and he had a job till we moved the transmitter in 2008. His navy pension isn't that much, so we get into a fight everytime I go raid his junkbox because I insist on paying him, IIRC that bank of huge caps, which have to be soft started else they'll trip a 30 amp breaker, cost me a $20 bill and I had to threaten him to get him to keep it.
> > El lun., 26 abr. 2021 17:50, andrew beck <andrewbeck0...@gmail.com> > > > > escribió: > > > 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 > > > > Leonardo Marsaglia > > > > _______________________________________________ > > 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 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
