I saw this discussed once or twice in irc or maybe on the mailing lists. I can think of a few ways,
1 separate axes and do some maths in gcode, this may be best because of the differing speeds and responses of the top/bottom on a knee mill. 2 use the scale comp and some interconnection of bottom to top axis in hal so that the resulting distance is part bottom part top but you then can only travel at the slowest axis 3 put more logic in hal and do the same as 2 but only move the bottom axis if you have to, could be faster most of the time For an example of linked axes using this sort of trickery see http://wiki.linuxcnc.org/cgi-bin/wiki.pl?Hobbing Dave Caroline On 04/01/2014, Gregg Eshelman <[email protected]> wrote: > A couple of examples. The knee and quill on a milling machine. The head > ram and table Y axis on an old Gorton mill. > > Can LCNC combine the two motions that are in the same plane to provide a > greater range than either alone? > > This would be especially useful on Bridgeport and clone knee mills that > usually have a quill travel around 5 inches. > > The Gorton is an old linear ram hydraulic True-Trace dinosaur. For the Y > axis it moves the ram and head in and out, but the table also has a long > manual motion with an ACME screw. With both combined it looks like its > total Y travel would nearly equal its X travel, which is all hydraulic > plus a tiny 5" manual range that was apparently used to fine adjust for > starting to trace the pattern. Gorton billed these as being usable as a > full manual mill... > > Given that the Gorton's head has no tilt or nod, it'd make a quite nice > CNC mill, no need to ever tram the head because it can't get out of > tram. Probably best to replace the hydraulic cylinders with ballscrews, > unless there's a way to precisely position hydraulic rams without direct > machine position feedback (linear scales). > > In any case the huge hunk of iron would have to come to my shop > extremely cheap. If it was the somewhat later version that used > hydraulic motors with chain drive to screws, I'd be all over that. Much > easier CNC conversion. > > ------------------------------------------------------------------------------ > Rapidly troubleshoot problems before they affect your business. Most IT > organizations don't have a clear picture of how application performance > affects their revenue. With AppDynamics, you get 100% visibility into your > Java,.NET, & PHP application. Start your 15-day FREE TRIAL of AppDynamics > Pro! > http://pubads.g.doubleclick.net/gampad/clk?id=84349831&iu=/4140/ostg.clktrk > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users > ------------------------------------------------------------------------------ Rapidly troubleshoot problems before they affect your business. Most IT organizations don't have a clear picture of how application performance affects their revenue. With AppDynamics, you get 100% visibility into your Java,.NET, & PHP application. Start your 15-day FREE TRIAL of AppDynamics Pro! http://pubads.g.doubleclick.net/gampad/clk?id=84349831&iu=/4140/ostg.clktrk _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
