If you added a mirror and a beam splitter you have the bones of a laser autocollimator.
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
