On Jun 7, 2008, at 11:30 AM, Jon Elson wrote: > Andre' Blanchard wrote: > >> What is the delay (in degrees of rotation) between reading the >> spindle >> encoder and positioning the Z axis? >> That delay would be in opposite directions going and coming out. > Unless there is mechanical backlash between the spindle itself > and the spindle encoder, this delay should be minute, somewhere > in the couple millisecond range. At a couple hundred spindle > RPM, it should be negligable. Indeed with the timing belt coupling between the spindle and the encoder and 1440 counts/rev emc should track pretty well. I suspect that backlash in Z will be contributory as it is probably 0.002 or so. Are we good enough to put a prox or other transducer below a tool and plot Z commanded motion( with halscope) against externally sensed motion? > > Backlash in the Z axis, combining all factors such as axis > following error, leadscrew backlash, spindle axial backlash and > spring in the link between ballscrew and quill are most likely > the culprit. This might be a lot easier to measure than the > actual error during a threading cycle. It would be a VERY > interesting experiment to perform, though, and could possibly > turn up some kind of quirk in EMC2, such as a software delay > introduced in the Z axis motion as it follows the spindle. I > seem to recall there is some "smoothing" applied to the Z motion. > > Jon > > ---------------------------------------------------------------------- > --- > Check out the new SourceForge.net Marketplace. > It's the best place to buy or sell services for > just about anything Open Source. > http://sourceforge.net/services/buy/index.php > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users
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