On Tue, 2013-04-16 at 20:37 -0700, Gregg Eshelman wrote: > Would a 0.0002" or 0.00005" resolution linear magnetic scale be good enough > to use instead of a servo encoder? > > Still trying to get the guy with the Acra mill in need of a bunch of TLC to > sell it for what it's worth as-is, not for what it'd be worth if it was in > working order? > > The old Anilam Crusader M system uses tachometers and glass scales so any > reason LinuxCNC couldn't use magnetic scales of higher resolution? > > Seems to me that it'd be easier to read the actual position of the table and > quill rather than inferring it from how many revolutions the motors have > turned.
Hi Gregg, I was told by a Boeing engineer that one need resolution to be five times better than the accuracy you are trying to hold. Understand that we really need two kinds of resolution; one for position and another for motion. Most of us would be rather happy if we could cut to 0.001 accuracy and repeatability. To get good motion you may need several times that resolution. I suppose that ideal systems would have linear encoders for position and encoders on the servo motor/ballscrew for motion. A emc person in trying to convince me to shift from glass scales to encoders once said, "the big companies all use rotary encoders and it isn't just for cost reason as they can afford to build and sell much more expensive stuff if it made a difference in performance". Just my tuppence. Dave ------------------------------------------------------------------------------ Precog is a next-generation analytics platform capable of advanced analytics on semi-structured data. The platform includes APIs for building apps and a phenomenal toolset for data science. Developers can use our toolset for easy data analysis & visualization. Get a free account! http://www2.precog.com/precogplatform/slashdotnewsletter _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
