unfortunately I'm not always at the pc ... I'm often away for work ... so .... but your problem made me think of something that I did a while ago ... a vision system that chose cards from a pile .... one of the problems was to find the symbols of the playing cards .... a basic part of the program was to identify the circle as a geometric figure .... so I thought: you fix the laser to the spindle ... shoot at a webcam that is on the tailstock .... at this point the center does not matter and even the cone of light with opencv we always identify the center of that kind of circle that the laser prints on the webcam ... the center will be very precise and you with a piece of iron you can always get to the center of the design you get on the webcam ... there is a bit of code to do ... but it can be a nice tool. Having said that today's LDVTs are very precise, they already have on board an electronics dedicated to the measurements and can have both digital and analog outputs ... so that you can use the mesa Analog input card
Il giorno lun 15 ott 2018 alle ore 00:13 Gene Heskett <[email protected]> ha scritto: > On Saturday 13 October 2018 18:43:25 Gene Heskett wrote: > > > On Saturday 13 October 2018 16:10:16 andy pugh wrote: > > > On Sat, 13 Oct 2018 at 15:03, theman whosoldtheworld > > > > > > <[email protected]> wrote: > > > > I think for your pourpose the better idea was using a very precise > > > > LVDT and put the measure of your axis in a table for make a good > > > > backslash linearization kinematics file .... > > > > > > Or use a dial indicator and a notebook. > > > > And a long, perfectly straight rod, turning slowly enough not to beat > > the $100+ dial to bits, and try to get an average reading. I'd need a > > 34" rod, a dog to turn it and an MT5 dead center, none of which I > > have. > > > > And from my experiments this afternoon, I am going to have to find a > > single spot beam green laser, this red line pistol cartridge model > > isn't going to give me good data, ever with its rotating - pattern > > beam. I've put a layer of cloudy poly on the cds and it helps, but it > > all goes to hell the instant the knife on the toolpost starts to > > interrupt the beam since the beam isn't round, and there does not seem > > to be a null at exactly half the beam blocked. I changed the drive > > belt to get more spindle revs, but at 1200 revs the front bearing is > > smoking in about 6 or 7 minutes with the bolts loose. And the reading > > still wanders around since the spindle is not synchronized with the > > meters A/D. So I've got to find a different way. I was hoping I > > wouldn't have to putz with building a camera, but that might yet be > > the only way. > > > > I'm getting my cataracts fixed starting next week, so this project is > > on hold for the time being. > > > Actually, blame it on oldtimers I guess, but I thought what would happen > if I put a honking big cap across the CDS cell, so I went out and stuck > a 4700 UF cap across it. This made the settling time several seconds, > but worked a treat, so now I have it well within a thou from just > clearing the 4 jaw with the side of a carriage, which is -3.500 in > machine coords based on my homing, on out to around 23 inches. There > seems to be a bump there, or the bellows is pushing, or perhaps I don't > have that screw bearing properly adjusted. Shop made bracket by an > amature, me. :( Thats about 1.5" from running into the tailstock. So I > feel like I actually accomplished something for a change. Murphy was > present and up to his usual mischief, the mouse battery died in the > middle of it, and of course I had to come into ther house ands get one > out of the coyote.den, and I'd give my left one to have a switch on the > DVM to disable its timeout shutoff feature. Batteries for it I have. > > FWIW, the maximum correction was about 3 thou, in the middle of the bed, > most corrections were under a thou. there's a bump in the middle of the > ways that I can't see, or feel thru a paper towel wiping it. > > But its better than it was. > > > Many many thanks for all the help and ideas I've been offered, even if > > my explanations lacked clarity, its appreciated, a lot. > > Thanks again everybody. > > -- > 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> > > > _______________________________________________ > Emc-developers mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-developers > _______________________________________________ Emc-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-developers
