On Thursday 03 September 2020 22:23:07 Ken Strauss wrote: > > -----Original Message----- > > From: John Dammeyer [mailto:jo...@autoartisans.com] > > Sent: Tuesday, September 01, 2020 1:03 AM > > To: 'Enhanced Machine Controller (EMC)' > > Subject: Re: [Emc-users] Tool presetter > > > > > -----Original Message----- > > > From: N [mailto:nicklas.karlsso...@gmail.com] > > > Sent: August-31-20 9:21 PM > > > To: Enhanced Machine Controller (EMC) > > > Subject: Re: [Emc-users] Tool presetter > > > > > > > I have one of these. > > > > Fowler 54-575-600 Electronic Edge Finder with Cylindrical Tip, > > > > 0.200" > > > > Stylus, 1/2" Shank > > > > > > I use it with the Shumatech DRO to find edges or the center of > > something > > > round. The DRO-350 has a feature for that. Eventually > > > > > I'll wire up a cable that can be sensed by LinuxCNC to detect the > > > edge > > > > automatically. > > > > > Was also thinking about a cable, however need to connect it each > > > time > > > > otherwise tool changer will slowly turn it into a twisted cable. > > > > > Expect they are more or less equally good as 3D taster but much > > > cheaper. > > > > Nicklas > > > > You make a good point. It should be possible to make some sort of > > holder which fits around a TT mill holder shank. The holder could > > have a small > > Blue > > > Tooth Low Power module that signals contact. > > > > The issue might be response time. Or noise that delays the contact > > signal > > > long enough to break the probe. > > It takes *VERY* little overtravel to destroy the tip of a small > carbide endmill. I wouldn't consider touching off onto a plate lacking > some sort of movement after contact with the endmill. > I have used a small bit of pcb material for a G38.2 contact. With the spindle turning backwards, its .0001" accurate and lasts till I goof up and destroy it. It registers contact for TLO setting with .0001" repeatability, and until I screw up, has never left a mark on the copper of the pcb. Similarly, a 3" piece of bare copper from the static ground of a piece of romex, stuck in a short piece of 3/4" teflon rod and that mounted in a TTS holder with a contact wire to it from the probe input has served as an edge and center finder for 20 years now. Spinning at say 500 revs, with a capacitor of perhaps .05 uf across it to hold the contact long enough for lcnc to sense it, has served as a center of a hole finder all of those same years. Accuracy is maybe .0002" worst case repeatability. Spinniing it, and the capacitor, holds the logic low from a very light contact long enough to register in linuxcnc.
My holefinder.ngc finds first contact, backs off 5 thou, and comes back in the selected direction, and records the 2nd contact, doing that in all 4 quadrants of a circle, and calculates the center of those 4 contacts. I have drilled a hole halfway thru a pcb, turned it over and using that method, finished drilling the holes in the pcb with no visible offset where the holes meet in the middle of the pcb's thickness. Around my place, thats plenty good enough for the girls I go with. Now, if I could just make it work for woodwork. What I have done is make half a brass cube soldered up out of small bits of sheet brass, screwed it to the jig and by g38.2ing into that, found the jig then flipped the jig away and machined the wood relative to that. I still have that motorized jig stashed away for the next time if I last long enough for a next time. 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
