On Sunday 22 July 2018 17:57:46 James Boulton wrote: > If you added a mirror and a beam splitter you have the bones of a > laser autocollimator. > Since there are $2 beam splitter/combiners on fleabay, is there some diagrams for this in the wikipedia? Sort of, whats diagrammed assumes the sensing is a mirror at the far end of the path. And its tilt is what measured. Not exactly what I had in mind.
What I'd need is something to measure the centering of the beam as the sensor is moved along the bed by the carriage. Bed wear registering as an off center beam. That grinding noise is getting louder. :) I'll chase a few more wikipedia links. Thanks James. > James. > > Sent from my iPhone > > > On 23/07/2018, at 9:42 AM, James Boulton <[email protected]> > > wrote: > > > > Replace your 4 photodiodes with a webcam without a lens. Put a tube > > in the lens place to reduce ambient light. This will give you a > > cheaper detector with higher resolution. Use a laser collimated to 3 > > to 5 mm. Then put a lens on the tool post. This lens will make a > > ‘light lever’ which will accentuate the laser deflection on the ccd. > > > > Sent from my iPhone > > > >> On 23/07/2018, at 6:21 AM, Gene Heskett <[email protected]> > >> wrote: > >> > >> Greetings all; > >> > >> In trying to come up with a means of measuring and compensating for > >> bed wear, it strikes me that a laser diode with a very small beam, > >> well under a 1mm diameter with minimal beam divergence would serve > >> as a light source. > >> > >> Then a 4 pixel ccd, with the pixels in a square pattern could serve > >> as a detector. If mounted at a 45 degree angle, one should be able > >> to separate the up-down error from the in-out error > >> > >> Mount the laser in the chuck, on center, and point it toward the > >> tailstock and diddle the aim until it hits whereever on a center, > >> but with as little wobble as it can be adjusted for, then move the > >> center until its hitting the tip of a dead center nounted in the > >> tailstock. > >> > >> bring the ccd into the beams path and adjust its position for equal > >> output from all 4 cells while mounted in the toolpost. All this of > >> course with the spindle turning. Run the carriage and the detector > >> toward the headstock, recording the average reading from each cell > >> every half inch or so. There will of course be an up-down error due > >> to wear, and there will also be an in-out error. If the updown > >> error is too gross, get out the moglic and build up the low spots, > >> but if they are reasonable then log the in-out errors and correct > >> them with a couple linearity modules and an offset module, based on > >> having the tool set dead at level with the work, the correction > >> ought to be pretty good, with well under a thou error if doing the > >> finishing cut with a grinder. > >> > >> So, is the improved accuracy worth building such a contraption? > >> > >> Or are there other, even cheaper ways of obtaining these > >> measurements? > >> > >> Thanks for any feedback. > >> > >> -- > >> Cheers, Gene Heskett > >> -- > >> "There are four boxes to be used in defense of liberty: > >> soap, ballot, jury, and ammo. Pleas > > ---------------------------------------------------------------------- >-------- Check out the vibrant tech community on one of the world's > most engaging tech sites, Slashdot.org! http://sdm.link/slashdot > _______________________________________________ > Emc-developers mailing list > [email protected] > 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> ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Emc-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-developers
