On Sunday 25 April 2021 08:24:49 Leonardo Marsaglia wrote: > Hello Andrew, > > Is there a baking resistor installed on your drive? I think a proper > one should solve your problem and you can keep the good deceleration > rates. > > Leonardo Marsaglia > > El dom., 25 abr. 2021 08:30, andrew beck <andrewbeck0...@gmail.com> > > escribió: > > hey guys > > > > not sure if my emails are coming through to you guys. hope they > > are. > > > > i have just successfully set up my encoder for rigid tapping using > > index signal from spindle motor encoder > > > > just got a few questions for the group > > > > is it possible to set different ramp values depending on spindle > > speed. > > > > if I try rigid tap at 1000 rpm at 1mm pitch i get a over travel of > > about 5mm. I can reduce the deceleration ramp in the altivar 71 > > schiender drive to 0.5 secs and then the over travel is about one > > revolution of the spindle. but if i leave the settings in vfd like > > that and then run spindle at 9000rpm the spindle goes into > > overvoltage faults. > > > > just wondering if I can maybe set use the ramp internally to > > linuxcnc to give me more control > > > > http://linuxcnc.org/docs/html/examples/spindle.html > > > > if i could specify a max rate of change and also a max ramp setting > > I think I could set the values up so that at high speed the max rate > > of change slows the spindle slowly enough that it doesn't trip vfd. > > while at low speed say under 1000 rpm the spindle can stop faster. > > or maybe I am just miss reading this all
I don't have a spindle system quite like what Andrew has described, probably the closest would be on my lathe with a vfd. There, and two other machines that can rigid tap, its a rather complex bit of hal I can email (PM, just ask) the files for, but that is best described: I treat the change in direction from motion by detecting it with an xor, so it works for both direction switches. Direction actually fed to the spindle controller is captured by the one shot timing out as the spindle is stopped by the limit3 in series with the speed signal, the initial action being a zeroed input to the limit3, with the limit3 output going to the controller. I also use Jon's (PICO) pwm-servo amp with dc motors, and like the vfd, its a full 4 quadrant controller, extracting the energy from the motor as its stopping and feeding it back into the power supply. Stopping either motor to a slow enough speed that a oneshot timing out due to the lengthening time between encoder pulses makes a good stopped indicator. When that oneshot times out, the mux2, functioning as a sample-hold is finally updated so it sends the new direction to the controller and the xor2. The xor2 then restores the speed signal to the input of the limit3 controller and that ramps up the speed to its former value. In the case of the sheldon lathe with a vfd fed by a pdm-generator driving a spinx-1, which controls the vfd, I can reverse a 40 lb 8" chuck, and I have some more hal watching and displaying that overtravel, and I have hub clamps on the backing plates to prevent unscrewing themselves from the spindle. The overtravel at 100 rpm is .25 turns, and at 500 rpm is just a bit more than 3.5 turns. Not much faster if I have an er42 collet in the spindle as the rest of the drive chains mass prevents making it any faster. Lots of spinning mass in an E-400 drive even w/o that big chuck. I can go a wee bit faster but the vfd goes into an overvoltage shutdown if I push the limit3 setting any faster. But still, .25 turns is pretty impressive for turning around a 40 lb chuck. I use the same basic idea on TLM, and my GO704 as both use Jon's pwm-servo as the motor controller, but for different reasons, on TLM to keep it from breaking drive parts which were never sized for a nearly 2 hp peak motor, and on the GO704, with a better quality but identically rated PMDC motor, to stop the following errors because the Z can't keep up with instant reversals. It takes z around 350 millisecs to turn around at 500 revs, but can do it in 400 even at 3000 revs. Thats a bit extreme on the go704's spindle power supply, running its dc voltage up to around 170 from its normal 126, considerably above the 130 volt rating of its filter caps, but its so quickly used up by re-accelerating the motor in the other direction that no measerable leakage heating has developed, and its been doing that for about 6 years now. No failures. And no circuit breaker trips. I bought a breaking resistor for the 6040's 24k motor, but have never hooked it up, it does not have the moxie to tap, and no encoder exists in the motors available for less than $3k bucks. No Z room to do anything about it either, that combined with the damp noodles for X suspension rods, makes light cuts with a mister running the order of the day. > > regards > > > > Andrew > > > > _______________________________________________ > > 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
