The facing mill I was speaking of fits into the spindle of the Discovery 308 (the troublesome one) with the Simodrive 611. It's the heaviest tool I have for the 308.
My concern about using the resistor to trick the drive into ramping up slower is it will report at speed even before it is at speed. Do you do any rigid tapping with the resistor in place? The spindle has to be in control by the controller so I can rigid tap which is 30% of the ops I do on that machine. Thanks for the ideas John On 5/30/2012 3:41 PM, ceen...@in-front.com wrote: > Hi John, > > Sorry for the delay - just got back from a meeting. I also updated my > email address so I can post again!! My ISP moved to Google services and > my > email address changed. The EMC list had blocked posts sent from my new > address. > > I'm guessing your 2.5" facing mill may not be rated at 7.5kW average with > peaks of > 15kW during acceleration and deceleration. Does your facing mill have > electronic drive controls or is it a plain 3-phase motor with belt > reduction? I'm guessing our 7.5kW spindle drivers were built with the > assumption there is a sturdy 3-phase supply to lean on. > > I posted a picture at: [LINK: http://flic.kr/p/c8pc7Y] > http://flic.kr/p/c8pc7Y showing the circuit mod. I > forget the exact resistor and capacitor values but I just experimented > with > a 5k and 220uF pair with a 10V bench power supply. To reach 90% of full > value (9.0V) it took 5 seconds. Using a 1k resistor with a 220uF will > reach > 90% of terminal value in 1 second. My selection gave me about a 2 second > time constant. Just now I emulated the Heidenhain 0-10Vdc control with a > bench power supply. Connecting the resistor to the cap to limit the rate > of > voltage rise on the capacitor and watching the cap voltage reach 9V took > 5 > seconds with the 5k resistor. I remember inserting a resistor first and > making sure the stepped speed program still achieved the RPMs I wanted it > to. If you program it for 2000RPM and it only hits 1500RPM then choose a > small resistor value. Somewhere in the 100 ohm to 4.7k ohm should work. > If > the resistor is too high a value compared to the input impedance of the > spindle driver you will simply have a drop in voltage at the spindle > driver > and never achieve the speed you want. So, start with 1k without the > capacitor and see if that changes your spindle RPMs. If ok then add (1) > or > (2) 220uF capacitors to suit. This will add 1 to 2 seconds of delay to > slow > the acceleration and deceleration of the spindle. > > If your spindle driver is analog like mine you may have a good chance of > modifying your machine too. Old analog is great. No digital protocols or > acknowledge packets to mess with. If you have schematics to the CNC > controller, look for the spindle interface lines. If there is just one or > two shown, you can break the connection and manually control the spindle > speed with an external bench supply, potentiometer, etc. > > My experience was pretty straight forward looking back on it. It was the > first rotary phase converter I built. When accelerating OR decelerating > quickly, the spindle power meter would max out at 180% (meter would peg). > This is normal for this machine. Accelerating would decrease the CNC's > voltages and decelerating and dumping the spindle's brake energy into the > rotary phase converter "grid" would increase the CNC's system voltages. > It > was apparent to me that is was starving for power while quickly > accelerating and I did not have a strong enough grid (rotary phase > converter) to brake against. If the engine is too big for a car and > starved > for gas or if the tires break loose while downshifting then don't > accelerate as fast or decelerate as fast. The RC delay fixed it. > > Let me know what you find in your schematics. > > > Dennis > > > >Hi Dennis, > > >I have a 2.5" diameter facing mill that I use and I don't notice any > >difference when using that. My machine lights do not dim during > >acceleration which I assume is a good thing. I'm in the same canoe as > >you with 240v single phase my only option to work with. > > > >Before all the experiments I could get 0 to 2k with no problems and > >would structure my programs around that or use the G4 pause and ramp up > >to the rpm I wanted above 2k. > > > >I too modified my program using a pause between S values but only had > to > >do that going up in rpm. From 6k to 0 I've never had a fault. > > > >The resistor/capacitor would be a low cost experiment. How do you > >calculate what the values are for the resistor and the cap? Did you put > >the resistor in series with one of the control lines? Does the cap > >connect to the upstream side or the downstream side of the resistor? > >Maybe a stick drawing would help me understand... > > > >John > ------------------------------------------------------------------------------ > Live Security Virtual Conference > Exclusive live event will cover all the ways today's security and > threat landscape has changed and how IT managers can respond. Discussions > will include endpoint security, mobile security and the latest in malware > threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
