On Thu, 29 Apr 2010 23:33 -0500, "Jon Elson" <el...@pico-systems.com> wrote:
> My first cut at rigid tapping just jammed the VFD from forward to > reverse command, which was so abrupt it caused Z-axis following errors > at higher spindle speeds. I have a lowpass component in there also to > make the speed change more gradual. A couple thoughts here: 1) The lowpass component generates an exponential response, with the speed changing rapidly at the beginning of the transition and slowly at the end. If you use a limit2 block, the speed ramp rate will be constant. If you adjust the ramp rate so the total reversal time is the same, the initial rate will be less than the lowpass and easier for Z to track. If you choose a rate that matches the initial rate of the lowpass, the reversal will be quicker. Win either way. 2) Most VFDs let you set a ramp rate as a configuration parameter, so you don't need either the lowpass or the limit block in HAL. Regards, John Kasunich -- John Kasunich jmkasun...@fastmail.fm ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
