Would "non-trivial kinematics" correct for non-square mechanical axis? It seems to me this is the way to correct the residual errors that all real-world machines have.
On Sun, Dec 12, 2021 at 8:40 AM Gene Heskett <ghesk...@shentel.net> wrote: > On Sun, 12 Dec, 2021 at 6:09 AM, me <ghesk...@shentel.net> wrote: > > > To: emc-users@lists.sourceforge.net > Greetings all; > > > I need access to the Z position that is G53 referenced as I need the > absolute > position on the post assuming the home switch abut 40 thou below the top > is at 0.00000. > > > Which hal pin or signal gives me that value? > > No answer so far, so let me ask a different way since I cannot watch the > #5XXX > > values with a hal meter to identify the var I need. > > > Is joint.N.cmd-pos the stable value I need? > > > Not changing with co-ord mapping or touch-offs, or even metric/imperial > measurement switches. > > > I am currently using it for Z pos reference as the pos input to a lincurve > module > whose output is directed to the X offset module "wired" up in hal to comp > bed > wear on the Sheldon, and that seems to be working well as it needs about 13 > thou of comp right in front of the chuck. It can now turn within a thou, > for at > > least 15" from the chuck. > > > > My GO704's post is not quite plumb, the boltholes that attach it to the > base aren't > big enough to allow it to be pulled plumb, so I either need to ream the > holes. or > > fix it with an offset in the X path, preferably based on a zero point at > the home > switches closure point. By inserting a tiny bit of Z motion in order to > not bend > a drill bit against the side of the hole as it descends. This bent drill > is quite > > visible. > > > > Ideal situation would having this joint.N.pos,cmd be 0.00000 at the home > > switch closure. > > > Then I want, not to use a lincurve module, but a scale module with a very > > small scale setp'd into it to develop a correction offset that might be > only > 50 thou in the height of the head travel. The head is currently well > trammed > to the table and a small X movement as Z descends could correct it, > drilling > and tapping round holes by moving X to make it stay plumbed as Z descends. > > > I have even broken taps with the non plumb sideways push at the bottom > of a hole. And obviously sloppy threads result. > > > > One more step IOW in my attempts to make a silk purse out of an $1100 sow's > ear mill. > > > > Thank you. > > Cheers, Gene > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net<mailto: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 > -- Chris Albertson Redondo Beach, California _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
