Clamp a dowel pin to the table and probe the od. On Thu, Feb 28, 2019, 10:25 PM Gene Heskett <ghesk...@shentel.net> wrote:
> On Thursday 28 February 2019 21:03:49 Jon Elson wrote: > > > On 02/28/2019 05:04 PM, Frank Tkalcevic wrote: > > > I have a cheap ebay $100 probe. I had doubts about the accuracy, so > > > I perfomed a test probing a precision disc from all orientations. > > > (The disc came from a 1"-2" micrometer - it is used to "zero" the > > > micrometer). > > > > > > The results were pretty poor, with the error ranging from 0.3mm to > > > 0.75mm. > > > > > > http://www.franksworkshop.com.au/wordpress/2019/03/01/touch-probe-ac > > >curacy/# results > > > > > >> I have no way to measure how good MY probe is. > > > > Yes, what I need is a standard for an inside mike. That > > would make it pretty easy to test several directions without > > moving anything. I did set it up by creating a program to > > measure two sides of a gauge block, and dialing in the > > "fudge factor" in the program to compensate for the apparent > > probe ball diameter. Since the Blum probe needs the ball > > deflected a fair bit to register, the computed diameter of > > the ball is quite different from the actual measured size of > > the ball. But, it seems to work pretty well. > > > > Jon > > Jon, have you considered setting a digital caliper to say .2500" and > locking it, then clamping it down well enough it won't slip while you > probe its gap. Maybe even mounting it on an upward faceing belt drive > rotory table so all angles of the probe could be explored? Its not > required that it be exactly .2500 inches, only that it was well zero'd > before you started, and that you can read whatever it is once opened and > locked. That would be the standard you are comparing the probe to. That > ought to make us some smarter about probes. Backlash comp would need to > be done first of course. > > > > > > _______________________________________________ > > Emc-developers mailing list > > Emc-developers@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/emc-developers > > > 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-developers mailing list > Emc-developers@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-developers > _______________________________________________ Emc-developers mailing list Emc-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-developers
