On Monday 11 May 2020 15:42:33 Chris Albertson 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.
Thats the sort of a fix I need for this I think. Grizzly may have shipped it better but takeing the post off canceled that and its fairly obvious. Come warmer weather I mat see if I can loosen those bolts and whack it a bit truer. I do have squares I trust cutting wood, but this is something else. Needs a wider track than a stamped square has though, but sticking a mag base carrying a dial to the head is certainly doable, and that should not care about the heads tram state, a different critter entirely. Hopefully I can loosen those screws where its sitting, I screwed up by back the last time I tried to move that beast as its some north of 400 lbs. So whatever I do is probably going to be done right where its sitting. Thanks for the conversation Chris, makes me think a bit farther out of the box, and thats good. > On Mon, May 11, 2020 at 11:52 AM Gene Heskett <[email protected]> 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 <[email protected]> wrote: > > > > On Mon, 11 May 2020 at 18:38, Chris Albertson > > > > <[email protected]> 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 > > > > [email protected] > > > > 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 > > [email protected] > > 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 [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
