The internal numbers in gcode are floats there is no rounding down unless you put small constants in your gcode, I calculate the tooth angle in gcode so internally it is as accurate as needed.
eg do not calculate yourself use a line such as #<angle>=[360/#<teeth>] I never see your problem and have been using linuxcnc since 2.2. I would see a problem if I did not nod the a axis to remove the backlash. Dave Caroline On 03/01/2016, Cecil Thomas <wctho...@chartertn.net> wrote: > I guess I wasn't as clear as I had hoped about my question. > To be more specific: > When the commanded value for a move is converted into steps (or > microsteps) and that number of steps contains a fraction....What > happens to the fractional part of a step???? > > I am not speaking of dropped steps as would be the case in a stepper > whose movement is inhibited by not being able to complete a step due > to load, velocity, acceleration, setup or duration. > I am only questioning whether LinuxCNC drops the non integer portion > of a step when converting from commanded position change to steps. > > I have assumed that the system can only issue steps as an integer and > that the fraction is dropped. If this is the case then the system > can ONLY "round down" so all commanded moves that don't convert to > integers wind up being short of the desired move. Never "long". The > only way the error can "even out" is by virtue of having the effect > balanced by equally "short" moves in the opposite direction. > > As I have designed my program there are many more moves in one > direction than in the other so I assume that the "shortness" > accumulates over a large number of moves. My calculations for the > accumulation of error in my system seem to match the measured > results. I can change my program to try to balance the forward and > back moves or I can add a stage of reduction to the A axis to reduce > the magnitude of the "leftovers" or both but before I proceed I would > like to be sure that the trajectory planner does as I assumed "Only > round down". > > > Cecil > ------------------------------------------------------------------------------ > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
