On Sunday 22 July 2018 19:11:22 James Boulton wrote: > Sent from my iPhone > > >> On 23/07/2018, at 10:32 AM, Gene Heskett <[email protected]> > >> wrote: > >> > >> 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? > > The ccd is on the fixed to the end of the bed. Use a lens with a long > focal length focused on the ccd with the tool post closest to the > chuck ( I’m assuming a lathe). As the lens moves closer to the ccd on > the carriage the spot will get bigger ( giving you z displacement) and > deviation will be proportional to carriage deviation. > But its not Z displacement I want to measure. I want to measure X, say at 1" increments of Z so as to develop an X correction that will turn a long part with zero taper regardless of bed wear.
I'll have to plead guilty to not describing that originally. As long as the bed wear is even on both front and rear rails, the turn diameter is not seriously affected, but if the wear isn't even, then that tilts the carriage, carrying the cutting tip with it, and its this tilt, and consequent diameter of cut change that I want the data to feed back to LCNC to compensate that error out of it. I would assume with some yet to be developed drive tech, we could drive the tool up and down, call it Y, dynamicly under cutting forces, and correct both, but that effect without that is a change in tool height of only maybe 15 thou, for a lot of bed wear, and that 15 thou is such a small X motion it can be ignored for anything short of grinding Hubble a new, perfect mirror, and its correction can be mapped to effectively zero real error from these measurements. Since the "eyeglasses" they fitted Hubble with are working so well, we both know thats not going to happen. It does need a service call though, something we cannot now do since the shuttles have been decommissioned, the reaction wheel gyro's are failing and we'll be lucky to get another years use out of it. And its orbit which is right at the absolute limit of what the shuttles could reach and have propellant enough to do a braking burn left, is decaying and unless Musk builds something he can lift on his new Falcon9 that can synch with it, connect and give it a 5 mph boost and stick around while a couple guys in suits replace the gyro's, then bring them back, its going to be 30 billion dollars worth of fireworks as it burns up. I'll be a bit sad as that thing is mankinds highest technical achievement in the last 25 years. > > 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 whi > > ---------------------------------------------------------------------- >-------- 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
