On Sunday 22 July 2018 17:42:48 James Boulton 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. > And the lens on the toolpost is all that moves? Or does the cameras ccd stay at a fixed location vis-a-vis the lens, moving as a unit?
That sounds doable although thats a bigger beam than most diodes, which are about 1.5mm's, and likely will be felt in the divergence as the carriage is moved. I'll see if I can round up the goodies. How long a f.l. for the lens? Cameras I have several of, of not bragging resolutions or fps's, some with focusing lenses but all with exposed ccd's if the lens is removed. Then I wonder if the pi has enough iron in its butt to run camview. That is yet to be determined. FWIW, the new camview fails in almost exactly the same manner as the previous version on an amd64 wheezy box. Python bug methinks. But if the pi can do it, that would give me target rings that cheese in a separate window can't. Ignore the grinding noises from my brain. Thanks. > 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 -- 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
