On Monday 22 November 2021 00:24:40 John Dammeyer wrote: > I'm running my AC Servo spindle motor as step/dir and can easily tell > LCNC to do 1 RPM. I also have the quadrature encoder on it so I can > do power tapping. The drive is through the MESA 7i92H as one of the > stepper channels as is the encoder signals. > > Is there a way to tell the spindle to turn until it finds the index > and stop so it's always stopping at the exact same spot? Like > decelerate to 0.5 rev per second (30 RPM) or slower and stop when the > index happens? With either an M5 or the button on the user interface? > > I currently have acceleration/deceleration set high so it reverses > quickly with power tapping. Not to mention the ratio from motor to > spindle isn't quite 1:1 because I didn't turn the pulleys exactly the > same diameter or groove depth. But on an M5 a deceleration to 30 RPM > and then a complete stop on the index edge. > > Thanks > John This is a separate problem, but it should be solvable even for me with a pwm-servo driving a 1 hp pmdc motor.
An expansion of what I'm doing when I reach up to change gears. I have a mux4 in the path to the pid with a limit3 between the output of the mux4 and the pid to slow the speed change at reversal into a ramp that the z axis can follow without throwing a following error when rigid tapping. The sel inputs come from 2 tally switches on the knob, so I have 2 of the 4 selections determined by the tally switches, neither of which is true unless the knob is within 2 or 3 degrees of fully engaged. This gives 2 positions of input selection on the mux4. So instead of zero volts on the other two inputs, a small setp runs the motor at about 30 or 40 rpm's. There's no engagement ramps to speak of on those plastic gears and that means the gears are moving plenty slow enough to self mesh as I turn the knob and the spindle only returns to the set speed when the gears are fully engaged and that particular tally switch closes. Control of the motor is quite instant in human time, but I can have it turning 1500 revs, wide open in low gear, reach up and turn the shift kbob, the motor is down to 40 revs in about 200 milliseconds, my wrist runs out of twist so I have to change grips to finish the shift, the gears remesh without stalling the knob and 200 milliseconds after it's home in high gear, the spindle is up to wide open at 3000 rpms. I think I could put a counter in the hal that was zeroed on the index, use that to oneshot the the slow speed signal, and stop it on the next index pulse since in my case the index is an ats667 watching a steel pin on the drawbar retainer cap. So the index remains timed to the spindle and another mux changes the scale so the pyvcp tach always reads the spindles real speed. Yes, the scale change is independent from the index but thats self correcting on the next index, so theoreticly I could set both the socket and the spindle to any arbtrary position. One of them needs to be adjustable and since I lock the spindle with a spring loaded pin to change tools, its the socket that needs the tweek. I still think the spring in the air motor thats making it overspin should be replaced with the impact screw tool since crowbaring its motor will be a considerably more precise stop without abusing a mechanical stop. More like hydraulics. The trigger replacement would be one of these: <https://www.ebay.com/itm/292529636989?_trkparms=ispr%3D1&hash=item441c20067d:g:LF0AAOSwDXJa2GmU&amdata=enc%3AAQAGAAACkPYe5NmHp%252B2JMhMi7yxGiTJkPrKr5t53CooMSQt2orsS%252Fwocn770hnih0B3mVHNZ5KfStvjoMLCX8LFETQxLOQSIc53KKgxPk0pbizZS7EqAMntvg7PP8jmK8U%252FUIgSuoa4I5xzNll1QXLYxdKQj6fX8VuJmOAA%252Bugm1N1pG1DD7xV62fIOK2x2YgNlZiqp7aHRksyk%252FtxONHnYXhMvW6U6DAFSKoFTK11WMaX6mD6YBj1AAm9YSMLJzDjMNXyDnsmJJA7YZ%252BJEOTlMqRFF9ouvNBhW%252Bfd1b5lCzupZXSgyOx%252BNWlOuhciMM16GwNItvdlZrZ3Ck%252Bg4aZjOXlqDEBWNPVM9TdJ0efbGJGnCJuKFHTfkuEWxQmRQgEAXTQtvWG27JdTDZnOe2kLz6R5n2YGjO5E80UyQfnSxQzTCBmNUIuNknD7cEjee5vxg%252B7JydaiQPaiUKqIkpINROyG7AVOyba8kzIxsKc618h1X6Q4nfnZFpIg2S2S391oRXE62KOYcW7wNVF%252BFYBtoptyxobdqBeZe2lyDa9edXaADS9WUlq31a1dmowLyPOWYe9%252Bp7k9AMSaIJLvAxoMvrrGDWBhT4yVcdkdhAxoZB3Zh4U156Q9OubGDrTBXRWS9Gt8AtVv11uojG%252FhxDHhIjn9MHkiMJwqxPxyJEcmztmJSc9b02RUBTatVCku9HnuX81lM%252FqUsEe4Bdie%252BTXWTpmOjn0e3EPi0rm3aXSe3zgi2OqzVwy3mfCvBD1CX2B9nDqCiexAQhqwg3UDnvRX3aFmSPaul%252Ft7ZCGCgAfLwD2Z9JfHwI%252F3MDTuVhROgQVi%252F2iDBbiFHQ0jsU4iEbnnKsbeYVnN%252Bkz27rjxn4euQI1s1rbMC%252B%7Cclp%3A2334524%7Ctkp%3ABFBM2MiP5qhf> at about $7 usd, drive it with both outputs of a pwmgen in mode 2. I assume you have a similar, fixed position spindle lock? I had to make mine. Doing that twice, to position the socket as its comes down to fully engage the drawbar should be doable with a dup of the same idea, but since that needs to be done while its up, maybe a second ring and magnet on the socket to make it work in the up position. That would also give you the rotational tweek for free. The impact driver, with a short 1/4" hex to 3/8" adapter should solve the socket dropping problem too. Cheers John, 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, 1940) 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
