Rollers and the like are not going to work. The gantry beams will not be straight, not will they be level not square with each other and even if they were when the temperature changes they will move.
You can use rollers and such for controlling speed but position is going to have to be measured relative to the work piece NOT the building structure. On Wed, Aug 23, 2017 at 8:55 AM, Rick Gresham <rickgres...@comcast.net> wrote: > I've wondered about simple driven rollers versus some sort of cogged, > non-slip system. If the position can be monitored and controlled in real > time, then it seems likely driven rollers would be totally adequate as long > as there wasn't too much slippage. > > > On Aug 23, 2017, at 2:21 AM, andy pugh <bodge...@gmail.com> wrote: > > > >> On 23 August 2017 at 05:17, Dave Cole <linuxcncro...@gmail.com> wrote: > >> > >> A 3D laser tracker was part of the control scheme to track the actual > tool > >> head location. > >> That way standard rack could be used for the positioning mechanism and > the > >> position could be corrected on the fly via the laser tracker. > > > > That might still be a good idea, because it seems that such a machine > > might need to be modular, so units that are friction-drive on standard > > rolled steel sections seems like a likely solution. > > There will be some tyre-creep, but the laser (or acoustic) feedback > > could correct it. > > I heard of a system where you have a microphone in each corner of the > > room and a "clicker" that is localised in space by clever acoustic > > processing. > > The application was measuring accelerometer positions when > > instrumenting a car or van body. If you have ever "walked" a Faro arm > > round a van body you would know why the system seemed attractive. > > > > > > -- > > atp > > "A motorcycle is a bicycle with a pandemonium attachment and is > > designed for the especial use of mechanical geniuses, daredevils and > > lunatics." > > — George Fitch, Atlanta Constitution Newspaper, 1916 > > > > ------------------------------------------------------------ > ------------------ > > Check out the vibrant tech community on one of the world's most > > engaging tech sites, Slashdot.org! http://sdm.link/slashdot > > _______________________________________________ > > Emc-users mailing list > > Emc-users@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > ------------------------------------------------------------ > ------------------ > Check out the vibrant tech community on one of the world's most > engaging tech sites, Slashdot.org! http://sdm.link/slashdot > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > -- Chris Albertson Redondo Beach, California ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
