Gentlemen, To be truthful with you I don't bother calculating an encoder count very accurate. I just want to get it close so I can put an indicator on the slide and adjust the count so the joint moves as close to the commanded move as I can get it. I then use the bidirectional lead screw compensation to correct for every inch or 1/2 inch of motion. Seems to work very good for me. thanks Stuart
On Sat, Feb 23, 2013 at 10:19 PM, Jon Elson <el...@pico-systems.com> wrote: > Bruce Klawiter wrote: > > I have just switch my mill over from linear scales to rotary encoders > and I can't get my input scale right. OUTPUT_SCALE is 1, Units-inch > > > > X axis has a 1250 CPR differential encoder, motor 14 tooth gear, screw > 21 tooth gear, .200 pitch screw. 1250 X 4 X 1.5 X 5 = INPUT_SCALE = 37500 > > > > Y axis 5000 CPR differential encoders, motor 14 tooth gear, screw 21 > tooth gear, .200 pitch screw. 5000 X 4 X 1.5 X 5 = INPUT_SCALE = 150000 > > > > Z axis 5000 CPR differential encoders, motor 14 tooth gear, screw 28 > > tooth gear, .200 pitch screw. 5000 X 4 X 2 X 5 = INPUT_SCALE = 200000 > > > > If these calculations are correct they don't work, to even be in the > ballpark of one inch of actual travel (+/- .020) equaling the DRO showing > one inch I need. > > X axis INPUT_SCALE =38500 > > Y axis INPUT_SCALE =750000 > > Z axis INPUT_SCALE =1000000 > > > > What am I missing here. > > > > > Are you absolutely sure your encoders are counting correctly? Have you > turned > each motor as exactly one turn as possible and observed the difference in > reading? (This should be done in both directions with the pos option of > the > diagnostic program. Note the program starts with an oddball value of 517 > in the position counters.) > > Having gears between the encoder and leadscrew is a bad idea, unless you > actually > mean timing belt sprockets. > > The fact that the numbers keep going up at vast rates between axes > indicates something is quite wrong. Are you absolutely sure these > values are being sent to the input scale parameter of the ppmc driver? > Possibly there is something wrong in your ini files (it would likely be > either in the .ini file or in ppmc_motion.hal, which reads the parameters > in the .ini file and sets the, into the driver with a line like : > setp ppmc.0.encoder.00.scale [AXIS_0]INPUT_SCALE > > If this line is somehow being tricked into picking up the wrong value > from the .ini file, that might be the problem. You should examine > the actual value with the "show hal configuration" utility that is > available from the Machine drop-down menu in Axis. > Examine the values of ppmc.0.encoder.02.scale, for instance, > and see if it is what you are putting into the .ini file. > > Jon > > > ------------------------------------------------------------------------------ > Everyone hates slow websites. So do we. > Make your web apps faster with AppDynamics > Download AppDynamics Lite for free today: > http://p.sf.net/sfu/appdyn_d2d_feb > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > -- dos centavos ------------------------------------------------------------------------------ Everyone hates slow websites. So do we. Make your web apps faster with AppDynamics Download AppDynamics Lite for free today: http://p.sf.net/sfu/appdyn_d2d_feb _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
