On Dec 22 2015 8:33 PM, andy pugh wrote: > On 23 December 2015 at 02:02, Jon Elson <[email protected]> > wrote: >> So, the spindle's >> rotational inertia makes jerk MECHANICALLY impossible. > > I don't think that there is a mechanical limit on jerk. > > This is why you stumble when a tube train stops hard.
I like to think of what happens when I apply the breaks on a car. It slows down, and if I do not let up a little near the end it grabs... I think that is technically jerk. As for applying gas, if you pop the clutch... Seriously though. The VLA example, they installed two motors (each feeding the opposite way, and would feed them propositionally to control jerk, and possibly higher order derivatives). They told me that when they originally had one motor on the system, the initial impulse would send a shock through the entire antenna. I could have the story wrong, but that is what I remember. Back to LCNC land... I can see this being useful for most cases, but not critically necessary unless I was spinning something less than a 24" chuck. I only had a chance to run a machine that large once, and that was decades ago. EBo -- ------------------------------------------------------------------------------ _______________________________________________ Emc-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-developers
