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. 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