I know that many manufacturers of machine use granite -rock as a table base in order to reduce thermal expention. it is not cheap but not expencive ither. those machine looks like large CMM machine. aram
> I think the problem with temp correction is where to put the > thermometer, ptd, etc. > Important components have widely differing thermal mass. > Might be easier to liquid cool/heat the major pieces ... or the room/ > enclosure. > I think some of the big boys cool/heat. > > Just my tuppence. > > Dave > > On Jan 21, 2008, at 1:02 PM, sam sokolik wrote: > >> wait - couldn't you use a temp sensor and have emc adjust the >> encoder scale >> (or something like that) on the fly? calibrate it once and it >> should be >> consistent.. Then you could use emc2's leadscrew comp (for lead >> screw/backlash inconsistencies) + temp correction. (or am I just >> dreaming?) >> >> just a thought. >> >> ----- Original Message ----- >> From: "Dave Engvall" <[EMAIL PROTECTED]> >> To: "Enhanced Machine Controller (EMC)" <emc- >> [EMAIL PROTECTED]> >> Sent: Monday, January 21, 2008 02:53 PM >> Subject: Re: [Emc-users] more scales >> >> >>> The SONY website show some of their scales with coeff of expansion = >>> steel and apparently others that match who knows what! >>> MMS a couple of months ago show an approach where there was a shop >>> made gage that ran alongside the >>> long work pieces and was probed before each job to determine >>> expansion corrections. Not the easiest thing and >>> pretty expensive for a one-off but for long term production it will >>> work. >>> >>> Good luck. >>> >>> Dave >>> >>> >>> On Jan 21, 2008, at 11:51 AM, Jon Elson wrote: >>> >>>> Stuart Stevenson wrote: >>>>> >>>>> The scales are SONY scales with an MD10A interpolator on them. >>>>> The >>>>> interpolator gives a max resolution of .5 UM. .5 micrometers is >>>>> 0.00002 inch. I don't know what the interpolator is configured >>>>> for. It >>>>> can be configured for .5, 1, 2, 2.5, 4, 5, 10 UM. >>>>> >>>>> >>>> OK, then, that solves THAT problem. At .5 um you get 50800 >>>> counts/inch, which should be good enough for nice smooth movement. >>>>> >>>>> I have DAC output from the ppmc boards to the A/B ac servo >>>>> amps. I >>>>> don't have motion yet. I am a lot closer. We will try to determine >>>>> why >>>>> the amps don't output later today. >>>> Unless the ballscrews have a lot of slop, you should be able to >>>> make it run just on the linear scale. Maybe much over 2 >>>> thousandths of an inch would get to a lot of rattling or >>>> excessive use of deadband. I assume these amps have tach feedback? >>>> >>>> Jon >>>> >>>> -------------------------------------------------------------------- >>>> -- >>>> --- >>>> This SF.net email is sponsored by: Microsoft >>>> Defy all challenges. Microsoft(R) Visual Studio 2008. >>>> http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ >>>> _______________________________________________ >>>> Emc-users mailing list >>>> [email protected] >>>> https://lists.sourceforge.net/lists/listinfo/emc-users >>> >>> >>> --------------------------------------------------------------------- >>> ---- >>> This SF.net email is sponsored by: Microsoft >>> Defy all challenges. Microsoft(R) Visual Studio 2008. >>> http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ >>> _______________________________________________ >>> Emc-users mailing list >>> [email protected] >>> https://lists.sourceforge.net/lists/listinfo/emc-users >>> >> >> >> ---------------------------------------------------------------------- >> --- >> This SF.net email is sponsored by: Microsoft >> Defy all challenges. Microsoft(R) Visual Studio 2008. >> http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ >> _______________________________________________ >> Emc-users mailing list >> [email protected] >> https://lists.sourceforge.net/lists/listinfo/emc-users > > > ------------------------------------------------------------------------- > This SF.net email is sponsored by: Microsoft > Defy all challenges. Microsoft(R) Visual Studio 2008. > http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users > ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
