On Sunday, August 21, 2011 12:31:01 PM Bryce Johnson did opine: > On my first setup with the slave X joint. I measured the distance and > it was correct. > > I switched to using the sample config that John pointed me to. Starting > off with the one doing no homing. > > The setups are pretty much identical except for the gantrykiins and the > settings for the additional axes. > > If I move the machine any faster then 50 ipm on any axes than i am > getting joint following errors for that axes. X gives joint follow > errors 0 and 3. Y gives joint follow errors 1. Z gives joint error > two. > > Any hints on what to try next? I attached my files I'm usng the Gantry > one is based off the link I got from John. my-mill1 is the slaved > config that is working with no errors. > > (Another issue that might be a bug. When I have a joint following > error. And I re-toggle machine power. The next command I give it will > have the old one in as well. For example. If my X axis gave a joint > error. I re-toggle machine power and give it a Y movement. Then it > will do the Y movement as well as the X... and the X movement will get > stuck on and i'll have to hit the estop.) > > Thanks > Bryce
Joint following errors seem to be (here at least) symptoms of the trajectory asking the individual axis's for more speed and acceleration than the axis's are set for or capable of. While it isn't quite a rule of thumb carved in granite, the trajectory planners vision of MAX_VEL and MAX-ACCEL should be 10 to 20% less than the axis settings, so that if an axis gets behind, there is 'headroom' available for it to do the catchup. When its not there, joint errors will generally occur. With steppers here, running on 27-28 volts, I have found I can actually move considerably faster if the ACCEL's are set slower. I can hear the motors doing the accels and decels quite plainly, with nearly a 3/4ths second of accel to speed or to stop if I set the jog faster than an axis's speed. With, on my toy, slow accels, I can do rapids at 20+ IPM for xy and their 20 tpi screws, and over 30 on the z with its 10 tpi screw, belted down from 17 teeth on the motor and 42 in the nut pulley. That however is sensitive to how recently I have given the column a drink of way oil, I am more out of counterbalance since I added the ALU bar carrying an HF die grinder to the face of the z sleds casting as this adds 3 or 4 pounds offset the the left. I need to rig a separate counter spring to the left end of that bar, but haven't found the pattern I can run thru potrace to make some round tuits yet. I think its a basic truism that one needs to have one before you can make some more. I need to make a whole pocket full for friends, including some on this list. ;-) 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) Who was that masked man? ------------------------------------------------------------------------------ Get a FREE DOWNLOAD! and learn more about uberSVN rich system, user administration capabilities and model configuration. Take the hassle out of deploying and managing Subversion and the tools developers use with it. http://p.sf.net/sfu/wandisco-d2d-2 _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
