On Sunday 22 March 2020 12:57:34 Leonardo Marsaglia wrote: > > You would have to turn the coolant off to measure, but have a look > > at laser triangulation distance sensors: > > https://www.micro-epsilon.co.uk/news/2018/2018-05-15-optoNCDT-1750LL > >/ (specifically mentions grinding wheels) > > Thanks for the link Andy. But these I assume measure distance, > reflecting the beam against a surface and then receiving it and > measuring the time elapsed between the two events am I right? > > I was thinking in something more like two IR barriers transversally > crossed by the wheel. The problem is, this is just an idea it came to > me because geometrically ,for me, this is the simplest way I came up > with to measure the wheel radius only depending on the accuracy of the > ballscrew and the motor driving it. But I don't really know if one can > achieve good levels of repeatability with such a setup.
That would be quite a heavy reponsibility on the ability to repeatedly dial in half of the beam blocked. I measured the bed wear of mt lathe with a 38 cartridge bore siting leser and an ir cell fixed to the point of a dead center in the tailstock, with the laser moditied for power thru a contact on the other end of a 18" tail sticking out of the back of the spindle and a cutoff blade raised high enough to block it fully. Fist adjusting thetail stock to center the beam on it photocell. Then mount the cutoff tool and advanced it in front of the receiver cell until half the beam was being cut off by the cutoff blade. Touched off x at 0.0000 at that point, jogged z a short distance each way to check for torque on the carriage, found under a thou, the jogged toward the spindle and recorded both z and the x jog offset. Every inch of travel. pretty close to a straight line for almost 20" of Z but then the bed wear closer to the spindle started to show so I wound up at he spindle pretty close to zero. Then I picked out the peaks and composed a settings table for a lincurve from that, inserted the lincurves output thru h offset to modify the x to keep its =- a thou or better over the z range checked. Taint perfect but it plenty close enough for the girls I've gone with. Ranges up to 8 thou if disabled. Using the method I've described I that methods accuracy budget would show that friction in the home switch would account for the huge majority of the errors, and I found those to be repeatable to .0002". or better. More than enough to measure thermal effects. > El dom., 22 mar. 2020 a las 13:52, Leonardo Marsaglia (< > > ldmarsag...@gmail.com>) escribió: > > You only need one beam. I would use the first beam interruption as a > > > >> second home switch of sorts, setting that with the home_offset when > >> you install a new wheel. The established home offset then becomes > >> your new wheel reference. This should then be considered a fixed > >> reference and a suitable distance from the work to prevent > >> accidental contact during setup. > > > > I was thinking about using the two beams that are transversally > > cut by the well because that way I can measure the length of a > > circular portion and have an exact measure of the radius > > independently of the home distance or the part diameter being known. > > The only thing that would matter with this approach would be to know > > exact distance between one beam and the other and they off course > > must be perfectly perpendicular to the wheel axis of movement. > > > > And obviously Leonardo, make a youtube video and tell us about it > > when > > > >> its working. :) > > > > Be sure I'll let you guys know as soon as I do something. In fact, > > I can't wait to see and show you the mazak turning with LCNC. After > > that, I hope I can start converting the grinder as soon as poosible! > > > > > > > > El dom., 22 mar. 2020 a las 10:41, Thaddeus Waldner > > (<thadw...@gmail.com>) > > > > escribió: > >> The most > >> > >> > primitive idea I have is to measure the wheel before placing it > >> > into the machine and then keep track of its diameter as it gets > >> > dressed. But sometimes we have to adjust the offset of the > >> > dressing tool because a diamond just detaches from the tool and > >> > then you need to correct for > >> > >> that > >> > >> > difference. > >> > >> I don’t know what the dressing system looks like, but if it’s > >> motorized in both axis( cut depth and motion across the wheel) then > >> why don’t you touch off the dressing point? You could do an initial > >> homing when machine starts, and again after each dressing > >> operation. Use the info to determine dressing point depth of cut > >> and also to infer actual wheel diameter. You could also use it to > >> catch the event of a diamond point being knocked loose, and alarm > >> the operator. > >> > >> > >> > >> _______________________________________________ > >> 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
