On Thursday, 31 March 2022 07:57:53 EDT andrew beck wrote: > For those interested I decided I really should start to use the forum > so people can search later for stuff hopefully I help someone. > > I have started on the gear sensor style encoder. > > > Hope it works. Let me know your thoughts > > https://forum.linuxcnc.org/show-your-stuff/45498-linuxcnc-machine-shop-> > fun-thread > > Regards > > Andrew > > On Sun, 27 Mar 2022, 22:21 Andy Pugh, <bodge...@gmail.com> wrote: > > > On 27 Mar 2022, at 08:09, andrew beck <andrewbeck0...@gmail.com> > > > wrote: > > > > > > And is bigger dia better for higher resolution? > > > > Probably not, as it will perhaps have more scope to oscillate at > > 10,000 rpm. > > > > Don’t neglect the purely mechanical design of this fast-spinning > > part. > > > > Have you considered optical sensors rather than inductive? > > > > What will be counting the pulses? > > > > LinuxCNC can lathe-thread with one sensor. > > But rigid-tapping is different as it needs to accurately detect the > > reversal point. So you need three channels for index and full > > quadrature.
And this is the problem with useing an ats-667 gear sensor. It switches on the approach, so the switch point, in only watching one edge, will have a different switch point depending on the direction. Some day, I've got the fix that. Needs a circuit from the quad detectors direction output, to dynamically switch the polarity of its pulse depending on which direction the quad detector says its turning. Thats active circuitry and needs to be MUCH faster than a hal thread. Probably in pure hardware. Ideally for that, an edge detector watching and firing on both edges with the first one "cocking" a trigger, and the second pulse then gated to the index circuit. That way the pulse seen as an index would be the one generated as the center of the trigger tooth is passing over the center of the ats-667. The ats-667 stays in that state until the next trigger is aproaching. So turning in one direction, its on 96% of the time, but in the other direction its off 96% of the time. > > Work out what error you can accept in the reversal point detection > > (as a fraction of thread pitch) and you can get a feel for how many > > slots you need. > > > > > > > > > > _______________________________________________ > > Emc-users mailing list > > Emc-users@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/emc-users > > _______________________________________________ > 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, 1940) If we desire respect for the law, we must first make the law respectable. - Louis D. Brandeis _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
