Hi Gene Have you considered a separately mounted probe. Have a look at these two Datron machine videos and see what you think. You seem to enjoy playing with offsets ;-) so it should suit you.
https://www.youtube.com/watch?v=_PC9ezN6cno https://www.youtube.com/watch?v=51FxvsCnMJc So, with a separate probe; - you never have to worry about fitting it into the spindle - it's readily available - wiring for the probe can be permanent - you can customize the probe as you progress Also, if the probe was mounted to the left of the spindle, you could add a USB camera to the right. Then you could eyeball(on screen) a jog to a feature, then run a probe routine, and then machine. Of course, one can swing the probe out the way, or have it on a separate vertical slider, and simply retract it. On Mon, 24 Dec 2018 at 20:17, Gene Heskett <[email protected]> wrote: > Greetings all; > > Thinking on probing on this new machine. > > Generally, the workpiece will be fastened to a spoilboard so that a drill > thru cuts into it rather than the slotted alu bed. This I'd assume can > be thought of as an insulator as a sheet of plywood seems ideal, and if > a more precise z reference is needed, it seems 10 thou can be skimmed of > the top in an hour or so. It would still be an insulator, meaning the > workpiece an be connected to the probe input for GP probing. I've been > useing a probe made from a needle threader, but with the fine wire > reformed into a sharper V, an have the spindle turning 100-400 rpms, the > wire loop then forming a cone, with a .1 uf capacitor that is discharged > if the loop touches at any point in its rotation, and being slow to > recharge, will hold that logic zero for long enough to register at > LCNC's probe input. > > My question then is, is there enough continuity up the motor shaft and > thru the bearings that it can serve as the ground? > > Or, because the motor has ceramic bearings its shaft is not grounded and > I'll have to rig a brush against the side of the probe itself (it has a > brass tubing shank of 1/8" OD) to assure a good grounding of the probes > tip) This has worked well, with a repeat accuracy well under a thou on > the little HF. > > Or should I figure on grounding the workpiece, and making a probe out of > a piece of 14 gauge wire, drilled into a round teflon rod that is in > turn chucked in the er-11, and the hot probe is a brush contacting the > wire, again with the holding capacitor to store the first fleeting > contact long enough to be seen by LCNC. I've done it this way too, and > have found the center of a drilled hole to a repeat error well under a > thousandth on the g0704. > > Now, to explore some what if's: > > If the spinning diameter was known, it could work in 3d, and assuming the > size of the hole was known, the distance it travels across the hole > could be used to determine that, by probing y-, y+, centering on that, > then centering on the x, and a repeat center on the y could give the > phantom diameter of the spinning probe by subtracting the travel from > the known hole size, which could then be picked up and used to probe the > sides of a workpiece, giving data close enough to use the align > utilities to orient the co-ords map so it autocorrects for a raw part > thats fixed at a small angle. I like that as I've never been able to > keep camview working long enough to use it for that on the g0704. I even > have the gui stuffs for that already installed in the g0704's axis! > Fiddly stuff changing the probe tool in and out, and may change its > working diameter if it gets sprung while remounting the probe tool but > it could work just fine as you can calibrate that error out. > > Would any of you have a better idea that doesn't cost $300? > > IOW, get all the precision needed from the probe itself each time you use > it, it recalibrates itself if you know how big the hole is and you are > useing the side of the probe. Cone tips would be out because a z diff > would modify the results. > > The possibility of permanently mounting a calibrating hole comes to mind, > calibrating against that, then probing the workpiece for alignment. > > Anybody like? I do. > > Merry Christmas everybody. > > 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) > Genes Web page <http://geneslinuxbox.net:6309/gene> > > > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users > _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
