As promised, here is the follow up: 1. After extensive testing of the A axis running a non-integer-step-producing angle several thousand iterations it appears, just as John K said, that the "leftovers' are dealt with within the planer in an intelligent way and there are no measurable residual errors.
2. The backlash in the rotary axis is less than .5 degrees. 3. The backlash for the Z axis is less than .002 but had been set to .005 in the .ini (it had to be me that put it there since no one else has touched the machine) 4. The real culprit was the Z axis. I put a dial indicator in the spindle and zeroed it at Z0 with the spindle traveling down. wrote a program to lift the indicator clear of the table and cycle the Z axis up and down 1000 times at G00 feed rate then run it back to Z0 moving down. It lost about .010 inches. I cut the max velocity and max acceleration by 25 percent and ran it again. The step loss was not detectable on the indicator. It would appear that the fat tooth was caused by Z axis step losses due to trying to move the axis up faster than it was comfortable with. (I can relate to that, It's how I feel sometimes) So... As the Fonz would say... " I was wr....wr....wr...wr...wrong" about the truncation of fractions of steps and I caused the problem by not setting up my max velocity and acceleration carefully enough. I also noticed that the temperature in my shop this time of year is around 50 degrees F while it often runs as warm as 80 in the summer. I'm guessing that I did the testing for the original max vel and acc in the summer when the lube was thin and now that it has thickened up a little there is more resistance to moving the axis. Guess it would be a good time to check X and Y to see if the season has affected them. Thanks again for the help. Cecil Thanks to everyone for their input. John answered the right question. The bottom line appears to be that Linuxcnc does "round" both up and down to the "nearest" step as opposed to just dropping the "leftover" ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
