Dave that is real nice. Can you post a few pictures and a little bit about it on the EMC Forum?
Thanks John On 7 Dec 2009 at 8:56, dave wrote: > Hi all, > For once I'm going to crow rather than eat crow. > > Discussions with Matt Shaver yielded an idea for a probe that was > not > the classical Renishaw ball and bar design. > > To wit: > Drill and ream 0.187 holes in a disk on a 2" bolt circle and press > 0.1875 ground dowel pins into the hole. Arrange so they protrude > approx .3". Drill a hole in the center of the disk and tap 1/4-28 > to > attach the probe. You will note set screws in the pic since I > didn't > have an undersize reamer. > > Mill holes 0.8" dia in another disk on the same bolt circle. > Make cups in .75 dia x .5" cylinders by drilling with a #2 > drill/countersink. Put teflon washers in the holes in disk and float > the > cups in epoxy using the dowel pins as a jig to align the cups. > Tap the cups with a 4-40 to attach electrical connections. > > The logic utilizes the inverting inputs on a hal logic 3 input OR > to > digital inputs on the stg card. A wire off the disk with the pins > goes > to digital ground. No pullups were necessary. > > see > > > http://imagebin.ca/view/UHmqcPz.html > > > > > Now for the proof of the pudding. > > Used G38.3 probe a ground surface to check Z repeatability. G code > was > provided by a C program that simply looped. (PROBEOPEN dataset_name) > and > (PROBECLOSE) were used to accumulate the data. > AFIK if one uses a path in the dataset name then spacing between > the > PROBEOPEN and the dataset name is not critical; otherwise extra > spaces > i.e. > 1 will be prepended to the data set name. Ask me how I know. > ;-) > For each test reps = 30. > > In like manner I probed the bed at 1" intervals and also used > movements > in X to probe the side of a ground bar. > > Note: resolution of the axes are 1 um in X and Y and about 1.5 um in > Z. > encoders are on the ball screw for X and Y and on the servo > motor > for Z. > > Results: std dev. > X probe: 0.00022" > Z probe: 0.000267" > Bed probe: 0.000634" > > I think I can live with these numbers for a shop-built probe. ;-) > > Many thanks to those hard working (and I might add bright) people > that > created the various components that made this this implementation > possible. > > Dave > > > > > > > > -------------------------------------------------------------------- > ---------- > Join us December 9, 2009 for the Red Hat Virtual Experience, > a free event focused on virtualization and cloud computing. > Attend in-depth sessions from your desk. Your couch. Anywhere. > http://p.sf.net/sfu/redhat-sfdev2dev > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users ------------------------------------------------------------------------------ Return on Information: Google Enterprise Search pays you back Get the facts. http://p.sf.net/sfu/google-dev2dev _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
