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. 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 ------------------------------------------------------------------------------ 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
