Hi Stuart, You can see that requirement in the arArcTest3_4.png I tacked on in a previous posting. The center point of the new arc has to move to a new position such that the starting radius from center to XStart and YStart matches the radius to XEnd and YEnd. The position of this center is referenced to the XStart and YStart locations and now has to be WOC longer.
John > -----Original Message----- > From: Stuart Stevenson [mailto:stus...@gmail.com] > Sent: September-24-19 12:13 PM > To: EMC2-Users-List > Subject: Re: [Emc-users] G-Code issue with IJ > > Gentlemen, > When using the R register in the circle interpolation routine the control > calculates the center point. It is almost 100 percent certain the center > point coordinates calculated using the R value are NOT the same coordinates > you use to calculate the IJ registers you put into the routine. Said > another way - the center point calculated using the R register is not the > center of the hole you are wanting to machine. > Just saying > Hth > > Stuart > > On Tue, Sep 24, 2019, 1:55 PM Todd Zuercher <to...@pgrahamdunn.com> > wrote: > > > I had taken the time to work out an approximation of a spiral using IJ > > arcs using parametric code for a Fanuc machine once. > > > > Here is what I had. > > % > > #100=0.07 (LOOP OVERLAP SIZE) > > #103=100. (FEED RATE) > > N1G00G17G20G28G40G80G91Z0M5 > > G90 > > G52X#107Y#106Z0 > > G8P1 > > M8 > > (1/4" O-FLUTE UP) > > G28G91Z0M05 > > G90T2002M06 > > T102 > > M03S14000 > > > > (1st pocket) > > #101=1.425 (X POSITION) > > #102=1.925 (Y POSITION) > > #104=[#100/4] > > #105=0.125+#104 > > G0G17G55X[#101]Y[#102+0.125] > > G0G43 H2 Z1.0 > > G1Z0.25F#103 > > G3I0J-0.125Z0.2 > > G3I0J-0.125Z0.15 > > G3I0J-0.125Z0.1 > > G3I0J-0.125Z0.05 > > G3I0J-0.125 > > N30WHILE[#105 LT 1.25]DO1 > > G3 X[#101-#105] Y[#102] I-0.005 J[0.005-#105] F#103 > > #105=#105+#104 > > G3 X[#101] Y[#102-#105] I[#105-0.005] J-0.005 > > #105=#105+#104 > > G3 X[#101+#105] Y[#102] I0.005 J[#105-0.005] > > #105=#105+#104 > > G3 X[#101] Y[#102+#105] I[0.005-#105] J0.005 > > #105=#105+#104 > > END1 > > > > Todd Zuercher > > P. Graham Dunn Inc. > > 630 Henry Street > > Dalton, Ohio 44618 > > Phone: (330)828-2105ext. 2031 > > > > -----Original Message----- > > From: John Dammeyer <jo...@autoartisans.com> > > Sent: Tuesday, September 24, 2019 12:34 PM > > To: 'Enhanced Machine Controller (EMC)' <emc- > us...@lists.sourceforge.net> > > Subject: Re: [Emc-users] G-Code issue with IJ > > > > > On 09/23/2019 10:35 PM, Chris Kelley wrote: > > > > > > > > > > > > I suspect the problem lies in the method for calculating CentDist on > > > > line 148. I'm not sure that method actually produces a I or J > > > > coordinate that is equidistant from both the start of the arc and > > > > end of the arc, regardless of decimal precision. > > > > > > > > > > > OK, I have to admit that I have only used this program in the R arc > > > mode, so it is possible I screwed up the I J calculation. It is not a > > > true spiral, it is a set of 90 degree arcs with the radius increasing > > > slightly every segment. I've used this for 20 years in the R mode > > > with good results, though. > > > > > > Jon > > > > Hi Jon, > > It works perfectly in the R mode for me too. And with MACH3 even in the > > IJ mode without complaint. But LinuxCNC is correct when it reports that > > the Radius is different between the start and end positions by up to as > > much as 24 percent. > > > > Doing it by hand and trial and error I was able to do 90 degree arcs like > > the R mode but the exact calculations to get there still escapes me. I > > think partly because I was not using the center of the hole as the starting > > position. For the Mecsoft AlibreCAM example I put the workspace origin in > > the hole center so I could see the symmetry for positive and negative > > movements. But of course your program has an offset called starting x and > > y which is more logical if we're working off a drawing and positioning the > > tool bit at the center of each round pocket (hole). > > > > What I'm trying to do, and it's really a complete waste of time for me > > since AlibreCAM does it for me, is figure out how to modify your program > to > > properly generate the IJ values. I don't like not knowing. I'll be able > > to get back to this later this afternoon. > > > > But do notice from the attached screen shot there's a 1" radius circle and > > then three quarters of a spiral starting at the same spot. The first two > > I,J parameters have one each set to 0 as your program does. But the third > > 90 degree arc now adds in the -0.05 width of cut offset into I while J has > > incremented by 0.05. So the state machine that determines I and J has to > > be a bit more complicated. It's doable. Just not sure how yet. > > > > John > > > > > > > > > _______________________________________________ > > > Emc-users mailing list > > > Emc-users@lists.sourceforge.net > > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > > _______________________________________________ > > Emc-users mailing list > > Emc-users@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
