Marc Bodmer wrote: >Dear List > >I have an XY plasma cutter (gantry) with an externally height >controlled (Dynatorch THC) W Axis for the plasma torch. >This is my primary tool. > >Now I would like to add a secondary tool on a Z axis mounted right >beside the W Axis on the gantry. This tool would be used for >engraving or drilling or the like. > >This mechanical setup however gives an offset in X and Y between >primary and secondary tool. > >I know I could compensate for this "tool offset" by setting G54 for >the primary and G55 for the secondary tool in the g-code. But I >would prefer a "cleaner" solution than that. Because with G54/G55 >these 2 toolpaths are shown in axis with the respective offset. > >I would prefer a somewhat "transparent" solution: select the >tool in the g-code and have the offset implicitly set. > >Are there any solutions better suited than G54/G55 ? > > You should be able to do this in HAL. You're only switching between two tool locations, so a pair of mux2 components with the X and Y offsets pre-loaded on their inputs can provide the offsets. You may even be able to use an M-code to switch the active offset (M6x to set an I/O bit - I don't recall the exact ones). You add the mux output to the motor-pos-cmd output from motion, and subrtact it from the feedback path before sending it to motor-pos-fb. The stepgen or PID should take care of the step change in position when the output switches, or you could have a limit3 block there for smoothing (noting that it will also be "in the way" during normal motion).
I'm pretty sure there are some details I've ignored, but that's the fun of doing new things :) - Steve ------------------------------------------------------------------------------ SF.Net email is Sponsored by MIX09, March 18-20, 2009 in Las Vegas, Nevada. The future of the web can't happen without you. Join us at MIX09 to help pave the way to the Next Web now. Learn more and register at http://ad.doubleclick.net/clk;208669438;13503038;i?http://2009.visitmix.com/ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
