The G33 says to do a synchronized move. This is physically impossible. The Z axis has some limit on it's ability to go from zero speed to the commanded speed. So the controller is reducing the spindle speed so as to match the ability of the z-axis motor.
ALL multi-axis moves are this way. You see it best on a milling machine where perhaps the z-axis is also the slowest. Say you are milling a 45 degree ramp that climbs upward to the left. The X motor would have to slow to match the max speed of the z motor. When a lathe cuts threads it is in real-life cutting a ramp. The spinach is turning in x-direction the carnage in z. You can only cut as fast as the slowest motor can move. And nether of the motors has infinite acceleration. On Tue, Jan 30, 2018 at 2:42 PM, <tom-...@bgp.nu> wrote: > We have CSS on and are threading with a G33 on our Emco lathe and we are > seeing the spindle decelerating during the cut. Seems like the spindle > speed should be fairly steady at a given X location during a G33 and what > it seems like is that the spindle is still decelerating to speed while it’s > in the cut rather than before the cut. > > We are rapid-ing (G0 in Z) out of the part at the center of the part (X=0) > and so CSS spins the spindle up to full speed as I’d expect (*) but it > appears that our spindle is still decelerating to speed as the next > threading pass is happening. We read that G33 will wait for > spindle-at-speed before looking for the index pulse. But our > spindle-at-speed signal seems to be high during the full cycle once the > spindle speeds up the first time. It seems like spindle-at-speed should go > low after rapiding out of the part as it moves to it’s next X location and > decelerates to it’s next speed at the cutting diameter. Or are we > misunderstanding spindle-at-speed when CSS is in effect? > > > (*) Is it normal that a G0 move also triggers CSS to spin up (or down)? > Seems like the trajectory planner would know where the next cutting move is > and not adjust the spindle speed until it needs to. In our case we are > rapiding out of the part at X=0 and the spindle speeds up when it doesn’t > really need to. > > -Tom > > > ------------------------------------------------------------ > ------------------ > Check out the vibrant tech community on one of the world's most > engaging tech sites, Slashdot.org! http://sdm.link/slashdot > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > -- Chris Albertson Redondo Beach, California ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
