On Friday 18 December 2020 13:16:00 Chris Albertson wrote: > 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)
I thought of that, then discovered just how much trouble it was to make the notch in the spindle flange and said screw it. With the current config, if it has not been moved, only moves it 5 degrees to find that edge of the notch, and back to zero which is usually about +.003 on the dro. That is very impressive, until you grab the chuck and discover about 1 degree of backlash at that parking point. I haven't totally blocked access to the adjustment lock screw but before I loosen that, I'll make a couple chisel cuts so I can tap it a thou at a time, and make sure theres no endplay in the worm. This piece of crap doesn't even have a ball bearing ball to cushion that adjustment screw, so there WILL be a high wear rate there. I've no clue what a REAL BS-1 is worth, but I'm beginning to rethink buying this Chinese junk. > 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 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
