On this post - I showed what happens to a shape as you increase Q http://www.cnczone.com/forums/linuxcnc-formerly-emc2-/206712-software.html#post1453562
sam On 2/16/2017 2:11 PM, Kurt Jacobson wrote: > OK, I see that you mean now. As they say, a picture is worth a thousand > words. (Though that does not seem to hold true when writing an essay for > English class!?) > > I still think naive cam detector is doing exactly what it is suposed to. If > the maximum deviation of an arc from a strait line is within Q they are > collapsed into a single linear move, which is exactly what I see in your > screen dump. > > Kurt > > On Thu, Feb 16, 2017 at 2:53 PM, Todd Zuercher <[email protected]> > wrote: > >> I didn't expect the Naive cam detection to do this. >> https://s2.postimg.org/ezy3wjfjt/bug.png >> Maybe I am reading the docs wrong. >> >> ----- Original Message ----- >> From: "Kurt Jacobson" <[email protected]> >> To: "Enhanced Machine Controller (EMC)" <[email protected]> >> Sent: Thursday, February 16, 2017 2:10:26 PM >> Subject: Re: [Emc-users] G41-42 and G64 Bug? >> >> I don't really know any thing about this, but I'd say that is the expected >> behavior based on the description of G64 Path Blending: >> >> "On G2/G3 moves in the G17 (XY) plane when the maximum deviation of an arc >> from a straight line is less than the G64 P- tolerance the arc is broken >> into two lines (from start of arc to midpoint, and from midpoint to end). >> those lines are then subject to the naive cam algorithm for lines.[1]" >> >> It sounds like your Q value is larger than the radius of your compensation >> lead out, so the arc is broken up into two line segments. Since these line >> segments are within Q of a linear move they are collapsed into one linear >> move, and since this linear move is within Q of the original linear move >> the whole path is collapsed in to a single linear move which is treated >> essentially becomes a long compensation lead out move. >> >> Just thinking out loud here, again, I am a complete noob so take this with >> half a grain of salt. >> >> [1] http://linuxcnc.org/docs/html/gcode/g-code.html#gcode:g61-g61.1 >> >> Kurt >> >> On Thu, Feb 16, 2017 at 1:32 PM, Todd Zuercher <[email protected]> >> wrote: >> >>> I was playing arround with G41 and G42 in a simulation and I think I >> might >>> have found a bug with the Naive CAM Detection. >>> The shape I was simulating was a semi circle with the start/end point on >>> the flat side and a single G2 arc move connecting the end points. >>> The simulation behaves strangely. With a tool radius of .125" and .25" >> and >>> staight G64 the tool path precisely followed the path (white and red >> lines >>> over lapped). With G64P0.001, the same. The expected behavior is cutting >> a >>> straight line parallel to the programed line offset the tool radius, cut >> an >>> arc around that end point to connect to the offset path of the commanded >>> arc cut. all good right. >>> With G64P0.001Q0.2 there is odd behavior. It moves in a straight line >> from >>> the beginning of the compensated straight line cut to the begining of the >>> compensated arc cut completely ignoring the compensated end point of the >>> straight cut. I know having such a large Q setting is a little odd. I >> also >>> see simular behavior with G64P0.2 (no Q specified, same as Q0.2) only >> with >>> more rounded corners. >>> I seem to see the odd behavior when ever Q is about 2/3 or more than the >>> tool diameter. >>> >>> -- >>> >>> ======================================== >>> >>> Todd Zuercher >>> mailto:[email protected] >>> >>> ======================================== >>> ------------------------------------------------------------ >>> ------------------ >>> Check out the vibrant tech community on one of the world's most >>> engaging tech sites, SlashDot.org! http://sdm.link/slashdot >>> _______________________________________________ >>> Emc-users mailing list >>> [email protected] >>> https://lists.sourceforge.net/lists/listinfo/emc-users >>> >> ------------------------------------------------------------ >> ------------------ >> Check out the vibrant tech community on one of the world's most >> engaging tech sites, SlashDot.org! http://sdm.link/slashdot >> _______________________________________________ >> Emc-users mailing list >> [email protected] >> https://lists.sourceforge.net/lists/listinfo/emc-users >> >> ------------------------------------------------------------ >> ------------------ >> Check out the vibrant tech community on one of the world's most >> engaging tech sites, SlashDot.org! http://sdm.link/slashdot >> _______________________________________________ >> Emc-users mailing list >> [email protected] >> https://lists.sourceforge.net/lists/listinfo/emc-users >> > ------------------------------------------------------------------------------ > Check out the vibrant tech community on one of the world's most > engaging tech sites, SlashDot.org! http://sdm.link/slashdot > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users > > ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, SlashDot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
