On Tuesday 16 February 2016 08:15:43 Robert von Knobloch wrote: > On 16/02/16 14:02, [email protected] wrote: > >> Pass over the switch might be possible? > > > > No. The datasheets I've read all say the same that you must activate > > the plunger straigt on. Any angle will give you bad performance. Any > > sideways stress on the plunger can kill the plunger assembly. > > > > The only alternative is to use a level-based micro-switch. That, > > however, will probably make it less accurate. Especially when you > > move over it side-ways. The angle of attack is too small with > > respect to the travel distance. > > > > -- Greetings Bertho > > Bertho, > > FWIW I made mine by using small, round bar magnets (ca. 6 x 15 mm) and > reed switch capsules. I milled out small (25mm) pieces of 10 x 10mm > aluminium and epoxied the switches and magnets each in one. These, I > glued to the machine with cyanoacrylate such they slide past each > another horizontally, with a small gap (no contact at all) . I haven't > measured the repeatability but it seems pretty good and they are cheap > and sealed against junk getting in. > > Cheers, > Bob I used the round buttons Grizzly put on the tables for hard stops but took the stops off and the button just rolls the wheel in the end of the lever as they go by for X&Y, and put a pointer on the head sled to hit the roller on a post mounted switch. All 3 can go on by without damaging the switch.
On the toy mill when I put some teeny ball screws in it, I put a switch with a plain lever to sense when the screw was about to come out of the nut by letting the lever come out as the end of the screw passed the root of the lever. That made a quite decent homing switch, so I then set the software limit to stop it a few thou before it hit the hard stops at the other end of the travel. But on that mill I have never tried to put a switch on the Z. It has the whole post to play on, so there aren't any sw limits and I just touch it off where ever I need it to be. On the lathe, Z switch is about an inch from the empty chuck to the empty toolpost, and X switch trip is about 5 thou from the X maximum backout, so I remove the tool holder from the QC post, and the ctl+home sequence finds X first, then since that will clear the tool post with anything under 2.5" in the chuck, goes & finds that Z home & then parks it at 2" away from the chuck. All 3 machines seem to have pretty good. On the lathe of course both measurements are completely arbitrary since there is not a way to put a tool point so it blocks a beam of light thats exactly on the centerline. Repeatability is more important, and that seems to be adequate. More important when turning is taper, and the best way to control that is to map X against Z but LCNC cannot to that so I have to put it in the gcode. And that works about 75% of the time, depending on the direction and backlash, but .002" accuracy is do-able for about 3 or 4" of Z travel. Then bed wear sets in and I've not tried to compensate for that, yet... However, hint hint, if X could be mapped according to Z, that would be the cats meow. Use one map when running in the chuck, and another when using a tailstock too. Any axis to any other axis would be the ice cream on the pie. Those are my major sources of error on all 3 machines. Accuracy of the screw thread itself hasn't appeared to be a problem, with acme or ball screws within my ability to measure it, but that would be a bit crude to do with my limited range indicator tools. 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> ------------------------------------------------------------------------------ Site24x7 APM Insight: Get Deep Visibility into Application Performance APM + Mobile APM + RUM: Monitor 3 App instances at just $35/Month Monitor end-to-end web transactions and take corrective actions now Troubleshoot faster and improve end-user experience. Signup Now! http://pubads.g.doubleclick.net/gampad/clk?id=272487151&iu=/4140 _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
