I do have a case where a "home" is needed on a rotary axis. It is a robot cart that uses a motor in place of a steering wheel to control the angle of the two front wheels. The wheels also turn but they are not homed, we assume the wheels are at zero at power-up. The steering homes to "center". I use two switches on the steering home so I know which direction to move, Center is when both switches are open.
I bring this up because you said you did not want to wait for a 359.9 degree rotation. With two switches you can always know on which half of the circle you are on. and never turn more than 180 degrees. (the microswitch rides on a ridge that covers 1/2 the circumference) On Fri, Dec 18, 2020 at 5:27 AM Gene Heskett <ghesk...@shentel.net> wrote: > On Friday 18 December 2020 05:23:45 andy pugh wrote: > > > On Fri, 18 Dec 2020 at 08:16, Gene Heskett <ghesk...@shentel.net> > wrote: > > > > Also for a rotary table I wonder if you could use a push button on > > > > a control pannel. You define home to be whatever you want. For > > > > example if you need to make 20 cuts to cut a gear, do you care > > > > where the firth tooth is on the black? > > > > > > Generally no, Chris, but there will be times, like when a gear > > > already has the keyway cut. :) > > > > I have not bothered with home switches on my rotary, it just homes > > where it is. (zero search velocity) as part of the home sequence. > > > > If there is already a keyway or feature on the shaft then I am not > > sure that homing really helps, unless it is a job that was left in > > overnight. > > (And in that case I would return to zero before shutting it down). > > > > Aligning to an existing keyway or flat is a touch-off process, not > > homing. > > That was my impression too, Andy, but I can drive it till the encoders > rawcount is maybe a dozen counts from zero, touch it off to zero, and > restart LinuxCNC and its back to -44 thousand counts on the restart. So > call me puzzled. Even nuking position.txt doesn't prevent it long term. > I parked it on the switch but didn't touch off to 0.000 before the last > shutdown and this is position.txt now: > > 0.00010004874109802 > 0.00000004978340956 > 6.24999990801172967 > -33.10949999999843385 > 0.00000000000000000 > 0.00000000000000000 > 0.00000000000000000 > 0.00000000000000000 > 0.00000000000000000 > 0.00000000000000000 > 0.00000000000000000 > 0.00000000000000000 > 0.00000000000000000 > 0.00000000000000000 > 0.00000000000000000 > 0.00000000000000000 > > Thanks Andy > > Cheers, Gene Heskett > -- > "There are four boxes to be used in defense of liberty: > soap, ballot, jury, and ammo. Please use in that order." > -Ed Howdershelt (Author) > If we desire respect for the law, we must first make the law respectable. > - Louis D. Brandeis > Genes Web page <http://geneslinuxbox.net:6309/gene> > > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > -- Chris Albertson Redondo Beach, California _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
