On Monday 11 May 2020 16:07:42 Stuart Stevenson wrote: > Gene, > > This tool will allow you to check the relative square of a machine > tool. > > https://www.travers.com/cylindrical-square/p/57-020-263/ > I did look at that Stuart, 3 or 4 years ago, but the price kept me from reaching for the card. Now its up another $40. But the card is in better shape too... > > > On Mon, May 11, 2020, 2:45 PM Chris Albertson > <albertson.ch...@gmail.com> > > wrote: > > Mathematically, you don't need an absolute reference. If you have a > > perfect mill it would still be a perfect mill if put in on a slanted > > floor. What matters is the relative angles of the axis. > > > > Yes we can mesure these angles with inexpensive tools assuming you > > have one "good" larger size square you can trust. Those cheap > > inductive distance sensors on eBay have sub-micron repeatibilities. > > They are intended for use as non-contact limit switches and they > > work well for that. If you put one in a chuck facing down you can > > detect axis tilt. In fact, you do the same with a dial indictor, > > Then you scan the sides of your "good" steel square. to detect > > z-axis tilt. > > > > What the system would do is do a scan and see the error. Then it > > would compute what compensation is required and does the scan again. > > This way it sees that moving in X or Y no longer effects Z. > > > > But there is nothing you can do about tool orientation. Drills and > > fly cutters can not be fixed but the system could report the angle > > you would whack it with a mallet then re-test. > > > > On Mon, May 11, 2020 at 11:52 AM Gene Heskett <ghesk...@shentel.net> > > > > wrote: > > > On Monday 11 May 2020 14:22:26 Chris Albertson wrote: > > > > So, lets say I have a machine that has non-tricial kinematics (I > > > > mill with the z-axis tilted 30 degrees) and I write the > > > > kinematics routines correctly. Then you are saying the machine > > > > will not honor accel and velocity limits? > > > > > > > > But all machines are like this, not 30 degress certainly but > > > > some number of arcseconds. A nice feature would be to > > > > compensate for all the errors, not just the bed. > > > > > > That then raises the question: What reference point then becomes > > > the one true reference? Do we have the reasonably priced tools to > > > measure it? For me that answer is no, but I have observed many > > > times that the hole I drill by putting the work in the spindle, > > > and a drill straight up from the bed, are oviously out of > > > alignment by the time that hole is 1" deep, I am bending the > > > drill. This is likely because it was required I remove the post > > > while installing the ball screws, and the post is attached to the > > > base with horizontal bolts into the rear of the base casting, > > > meaning any slop in those boltholes will allow the post to lean > > > left or right at least a degree. And it is very noticeable. But, > > > where is the square that I can use to loosen those 4 bolts that > > > mount the post to the rear of the base casting, and adjust it for > > > plumb? Such a _3_ dimensional square isn't for sale that I know > > > of. > > > > > > > I would not be surprised if non-trivial kinematics is broken as > > > > so few people have machines with not-square axis the code would > > > > not be well tested. That said, te velocity problem is > > > > proportional to the cosine of the tilt. It is going to be tiny. > > > > > > > > On Mon, May 11, 2020 at 11:03 AM andy pugh <bodge...@gmail.com> wrote: > > > > > On Mon, 11 May 2020 at 18:38, Chris Albertson > > > > > > <albertson.ch...@gmail.com> wrote: > > > > > > Perhaps kinematics is the place to do the > > > > > > bed compensation. > > > > > > > > > > We tried that with "probekins" and it turned out not to to > > > > > work very well. external-offsets seems like a better way as it > > > > > honours accel and velocity limits. > > > > > > > > > > -- > > > > > atp > > > > > "A motorcycle is a bicycle with a pandemonium attachment and > > > > > is designed for the especial use of mechanical geniuses, > > > > > daredevils and lunatics." > > > > > — George Fitch, Atlanta Constitution Newspaper, 1912 > > > > > > > > > > > > > > > _______________________________________________ > > > > > 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 > > > > -- > > > > Chris Albertson > > Redondo Beach, California > > > > > > _______________________________________________ > > 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) 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
