Igor Chudov wrote: > Jon, siggen is very nifty. Thanks. > > I spent some time adjusting Z parameters yesterday. A change of P from > 300 to 550 has made the servo motor a lot stiffer, and now the best I > can do by hand, is move the Z axis by about 0.0003" or so. I can live > with it. > Yes, that sounds pretty good for a hobby/home shop machine. Mine is down in that region until I overpower the servo amps. > So, what would you say, does velocity mode provide in extra benefits? > Precise speed control at low speed? > Yes, it theoretically enables the machine to retain smooth motion at speeds where the encoder counts are coming in VERY slow. I did some testing WAYYY back in the EMC1 days, when I was setting up my own servo amps, back about 1998, where I was getting smooth motion down to where the encoder counts were coming in at 3 per second. Below that, stick-slip friction became dominant, but I'm not sure the encoder counts were the cause.
I BELIEVE, but can't prove it, that a torque-mode system would not be able to keep this smooth motion down that low. You can do some tests, like put an ultra-fine point pen in the spindle, and tape paper to a block in the vise. Then program an arc of as large a diameter as will fit, or just an arc sector including where an axis will reverse direction. This makes the stairsteps pretty visible. If not stairsteps, then it should be good enough. Jon ------------------------------------------------------------------------------ Start uncovering the many advantages of virtual appliances and start using them to simplify application deployment and accelerate your shift to cloud computing. http://p.sf.net/sfu/novell-sfdev2dev _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
