Spindle load is certainly one way to do it. Whether you do spindle load or force your cam is going to have to do a good job of keeping the cutter load constant or you will end up setting the trip too high to do much good. The same is true in trying to control such things by setting following error rather tightly.
Dave On Feb 11, 2008, at 4:02 AM, Gene Heskett wrote: > On Monday 11 February 2008, Dave Engvall wrote: >> IIRC - some years ago there was some talk about limiting force on >> each axis or the x,y vector. >> I don't think it is easy to do but something to think about. I have >> no idea how much difference there >> is between the forces for a 'good' cutter and a cutter on the edge >> of going bad. >> Something for someone with time on their hands to experiment >> with. ;-) >> > No idea if this is worth a shot or not, Dave. I was recently > trying to do > something on my micromill that resulted in several boxes of blown 2 > amp > spindle fuses because the servo has a quite high gain and I wasn't > aware that > the spindle was being overloaded. > > So I went out to radio shack and got a small project box, a 15 volt > dc meter > which they didn't state but I deduced was just the movement of a 1000 > ohms/volt meter and a 15k resistor, but only has an 85 ohm internal > resistance. A card of 1 ohm 10 watt r's, a card of 1500 ohm 1/4 > watters, > and a 4 amp 400 volt diode bridge. > > Placing the AC terminals of the bridge in series with the fuse to > rectify the > current, and a 1 ohm 10 watter across the bridges dc output, and > the meter > with its 1500 ohm scale resistor across that, gives me a 0-1.5 amps > full > scale meter, live in real time. > > So now I can see how hard the spindle motor is working. > >> Dave >> >> On Feb 10, 2008, at 9:15 PM, Stan Blosser wrote: >>> I'm not an expert on AC servos (or servos at all for that matter) >>> but I suppose the same tecnique could be used to measure torque on >>> nearly any motor, but keep in mind it is an offline process. This >>> is not something done directly by EMC or the motor controller. >>> >>> The setup for my measurements: >>> The stepper motor mounted on a bar suspended several feet above the >>> floor. A 1.5" diameter pulley mounted to the shaft. A string >>> wraps around the pulley and goes down to a basket for holding >>> weights. >>> My method for measuring torque went like this: >>> Set EMC to a very low jog rate. Initially about 1 inch/minute. >>> Load a basket with with weight. >>> Jog EMC so that it runs the stepper, which like a winch, lifts the >>> basket. >>> If everything works fine, jog in the other direction to return the >>> basket to the floor. >>> Continue to load the basket and jog until the stepper mis-steps >>> once fully accelerated. >>> Upon failure, note the weight and jog rate (which gives me the >>> values for the table on my site). >>> Remove some weight from the basket. >>> Increase the jog rate, attempt to lift the basket, and continue >>> increasing the jog rate until the stepper mis-steps. >>> Upon failure, note the weight and last successful jog rate. >>> Remove more weight and repeat the process. >>> Like I said, this is an offline process though. It is meant to be >>> a method for approximating certain design variables, rather than as >>> feedback for an active system. >>> >>> [EMAIL PROTECTED] wrote: >>>> Hi >>>> Can you measure torque on AC servo motor? >>>> Can I put that if torque exceed some certain level STOP machine or >>>> go to >>>> feed hold mode. It is very important because torque can directly >>>> show >>>> condition of cutter. If can stop machine when torque start >>>> increase I may >>>> or better will prevent break of cutter. >>>> I think in program need be include variable that limits maximum >>>> torque to >>>> axis. >>>> I am interesting in your work and let me know if it can be used >>>> with AC >>>> servomotors? >>>> Thank you >>>> aram >>>> >>>>> Doh! Of course, a link to my site would help: >>>>> >>>>> http://www.theblossers.net/index.php?section=15 >>>>> >>>>> Stan Blosser wrote: >>>>>> I just posted a blog article on my site regarding my recent >>>>>> stepper >>>>>> torque measurement project. Not directly relating to EMC, but I >>>>>> felt >>>>>> it relevant enough to share here. :-) >>>>> >>>>> ------------------------------------------------------------------ >>>>> -- >>>>> ----- >>>>> This SF.net email is sponsored by: Microsoft >>>>> Defy all challenges. Microsoft(R) Visual Studio 2008. >>>>> http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ >>>>> _______________________________________________ >>>>> Emc-users mailing list >>>>> Emc-users@lists.sourceforge.net >>>>> https://lists.sourceforge.net/lists/listinfo/emc-users >>>> >>>> ------------------------------------------------------------------- >>>> -- >>>> ---- >>>> This SF.net email is sponsored by: Microsoft >>>> Defy all challenges. Microsoft(R) Visual Studio 2008. >>>> http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ >>>> _______________________________________________ >>>> Emc-users mailing list >>>> Emc-users@lists.sourceforge.net >>>> https://lists.sourceforge.net/lists/listinfo/emc-users >>> >>> -------------------------------------------------------------------- >>> -- >>> --- >>> This SF.net email is sponsored by: Microsoft >>> Defy all challenges. Microsoft(R) Visual Studio 2008. >>> http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ >>> _______________________________________________ >>> Emc-users mailing list >>> Emc-users@lists.sourceforge.net >>> https://lists.sourceforge.net/lists/listinfo/emc-users > > > > -- > Cheers, Gene > "There are four boxes to be used in defense of liberty: > soap, ballot, jury, and ammo. Please use in that order." > -Ed Howdershelt (Author) > Not one hundred percent efficient, of course ... but nothing ever is. > -- Kirk, "Metamorphosis", stardate 3219.8 > > ---------------------------------------------------------------------- > --- > This SF.net email is sponsored by: Microsoft > Defy all challenges. Microsoft(R) Visual Studio 2008. > http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
