Hi Gene, The Renishaw-type probe is explained fairly clearly over here: http://www.indoor.flyer.co.uk/probe.htm . The idea is to have three conductive rods, spaced 120 degrees apart, lie on six balls, so you have a proper kinematic seating. Each rod closes the contact between two of these balls and lifting the rod breaks the contact. Three of these balls/rod combinations are wired in series, so breaking contact with just one ball breaks the entire loop. Major advantage of this setup is the ability to use it in any direction, as tilting the probe will break the loop, too. Precision is a bit hard to state, but with a VERY makeshift version (three thick copper wires for rods, each resting on two sharply bent copper wires for balls - makes sort of a torus-shape, bit hard to explain. Look at the bottom of http://wiki.linuxcnc.org/cgi-bin/emcinfo.pl?SandBox to see what I mean), I was able to get a repeatability of approx. 0.001" in the horizontal plane and 0.00008" (!) in the vertical direction. Using proper materials (ball bearings and hardened steel rods), I'm positive you can even get the horizontal plane within the micron range (~0.00004"), so this should suffice for most purposes.
Of course, you could also use just a "simple" plunge arrangement, with a probe sliding up and down. However, you should probably ALWAYS use a normally closed switch config. That way, you can use a rigid switch for higher accuracy, while still giving the probe room to "give way" when the machine decelerates. Good luck in trying any of this stuff out. Marc. ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
