On Thursday, February 24, 2022 11:43:45 PM EST Thaddeus Waldner wrote: > > That is likely because motion is aware its moving, but there is no > > feedback of a signal showing that it has moved to show motion it is > > following orders. I have a pair of 100 ppr dials on my sheldons > > replacement apron, which I use to drive it since there are no cranks > > on mine, motors having replaced the cranks. And I just spent 20 > > mins studying my hal file to find that coupling, but that hal file > > is now several years old, and apparently not well enough commented > > to let me get my ancient head back into what I was thinking back > > then. At 87, can I plead oldtimers? > > I suspect you connected them as MPGs, as that would be the most logical > thing to do. I don’t think I want MPGs because the axis need to move > during NC moves. > > Perhaps if I were more clear as to what the purpose is of this axis … > > I plan to use this axis with the linuxCNC probe features to > automatically record the profile of a surface as the Y axis moves > across that surface. The probe will have a roller on the end, which > will be held in contact of the surface by gravity or a spring. > > At this point, I am trying to find the correct hook to feed the > position/velocity from the encoder into the joint, as Gene suggested, > to get rid of the following error. Do I even need the stepgen? Can I > have a joint without a motor? Can I configure the joint to ignore the > following error and still get good position feedback? > In that case, I'd design the probe to be held in the x axis, or crossfeed if this is a lathe, with its own self contained contact closer, move y by whatever increment is needed to get the y accuracy you need, and use the std g38.2 probe to record the trip position.
I use the cheapest roller tipped, under a buck each by the bag, teeny micro-switches for homing, and normaly get .02mm or better repeat accuracy's from them. You'd have to write the scanning routine, logging the results to a file for later processing, but its something you could start at quitting time, turn out the lights and it may or may not be done by lights on the next morning. Scanning something held in the chuck or between centers, would not if its round, even need the spindle to be turning. Scanning a camshaft OTOH, would require the ability to position the spindle by the degree or even less, and its position would then be logged but then you'd only need 2 reaings per lobe since there is often a teeny taper to encourage a flat or mushroom faced tappet to spin and equalize the wear. With roller tappets that is not done because the tappet is pinned from rotation anyway. For cams, note that profiles are often patented. 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 Genes Web page <http://geneslinuxbox.net:6309/gene> _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
