On 03/04/2014 03:32 PM, Robert Ellenberg wrote: > Since I wrote the original question, I've been able to understand NCD much > better, so some of what I said originally no longer applies. The example I > showed wasn't terribly good, but since then I've been able to find a better > one here: > > https://www.dropbox.com/s/ixt2yuv6lvw0blp/naive_cam_quirk.png > > Here's a snippet of G code that produces that path (uncomment the > appropriate G64 line). > > G90 G20 > G64 P0.1 Q0.0 > (G64 P0.1 Q0.1) > G0 X0 Y0 Z0 > G1 X2 > G1 Y.1 > G1 Y.2 > G1 Y.3 > G1 Y1 > G0 X0 > Y0 > M2 > > Qualitatively, it seems like most of the time, your assertion is correct, > and the difference is slight. This particular case shows the effect more > dramatically. Incidentally, this also shows another liability with large > NCD tolerances. The move from X0.0 to X2.0 becomes a move from X0.0 to > (X2.0,Y0.1), which means that entire motion is shifted, and the toolpath is > no longer parallel to the X axis. Setting G64 P0.1 means the user would > expect larger blends, but they may not be expect this big deviation along > the whole line. It's possible that they fully understand the implications > of NCD, but if they don't, then this behavior will be a real > head-scratcher. >
Someone complained about this non-parallel behavior on www.practicalmachinist.com a few months back. -- Chris Lesiak Principal Design Engineer, Software LI-COR, Inc. chris.les...@licor.com Any opinions expressed are those of the author and do not necessarily represent those of his employer. ------------------------------------------------------------------------------ Subversion Kills Productivity. Get off Subversion & Make the Move to Perforce. With Perforce, you get hassle-free workflows. Merge that actually works. Faster operations. Version large binaries. Built-in WAN optimization and the freedom to use Git, Perforce or both. Make the move to Perforce. http://pubads.g.doubleclick.net/gampad/clk?id=122218951&iu=/4140/ostg.clktrk _______________________________________________ Emc-developers mailing list Emc-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-developers
