On Wed, 29 Feb 2012 10:54:20 -0500 Dave <[email protected]> wrote: > I have a friend who is an engineer who sets up laser trackers on > those big mills all over the US. The only way you can maintain .005 > tolerances over 50 or 60 feet on a big gantry machine is with a laser > tracker. They do coordinate compensation on the fly. > Siemens has a plug in interface that they use to do that. > > That 100 foot long mill is the biggest one I have heard of. Most of > the big ones are used for military contract work. > > There was a big one for sale on Ebay last year - still erected. I > think it was 50 feet long. It never sold on Ebay. > > Dave > > > > On 2/29/2012 4:39 AM, Roland Jollivet wrote: > > On 29 February 2012 10:56, Dave<[email protected]> wrote: > > > > > >> There is a lot of BS on that webpage. Optical encoder accuracy.. > >> Impressive to those who don't know better I guess. > >> > >> This is really the only important fact regarding accuracy: > >> >>We use Leica laser trackers to measure the volumetric Cartesian > >> errors. These devices have accuracies of approximately 0.002 > >> inches (51 microns) in our working envelope. > >> > >> Those are required to get any decent accuracy on a machine that > >> large. That machine probably grows and shrinks a quarter of an > >> inch or more with temperature swings. > >> > >> Dave > >> > >>> > >> > > > > What temperature swing? 0.2deg ? Temp control is cheap. > > > > Regards > > Roland
That mill would have set up nicely in the missile bay of an Atlas site. Masses of reinforced concrete, underground but not deep, sliding cover over the bay to allow one to use a crane to swing in large parts. Pretty much constant temp but not as good as the Titan sites which were much deeper. Of course, they were based out of Fairchild AFB near Spokane and scattered around the wheat country of the Big Bend. The Atlas sites were a tremendous injection of capital into farming country. Naturally, they were obsolete by the time they were completed. The missile were moved to Vandenberg AFB and used as boost vehicles for sat launches. It is rumored that about 50% of them actually got off the launch pad and flew right. ;-) Dave > > ------------------------------------------------------------------------------ > > Virtualization& Cloud Management Using Capacity Planning > > Cloud computing makes use of virtualization - but cloud computing > > also focuses on allowing computing to be delivered as a service. > > http://www.accelacomm.com/jaw/sfnl/114/51521223/ > > _______________________________________________ > > Emc-users mailing list > > [email protected] > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > > > > > ------------------------------------------------------------------------------ > Virtualization & Cloud Management Using Capacity Planning > Cloud computing makes use of virtualization - but cloud computing > also focuses on allowing computing to be delivered as a service. > http://www.accelacomm.com/jaw/sfnl/114/51521223/ > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users ------------------------------------------------------------------------------ Virtualization & Cloud Management Using Capacity Planning Cloud computing makes use of virtualization - but cloud computing also focuses on allowing computing to be delivered as a service. http://www.accelacomm.com/jaw/sfnl/114/51521223/ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
