Hi Martin, May be a fast short reply but the first minute of the video completely described the problem. While on doggy walk this morning pondering the problem I knew the solution had to be as described in the video. But I didn't realize there is a G93 that is used in conjunction with a post processing of the G-Code file. A very simple solution.
Didn't think I was running into something new. But that video link you posted didn't show up when I googled the problem. And most forum posts were also even ignorant of the issue which really surprised me. Thanks John > -----Original Message----- > From: Martin Dobbins [mailto:[email protected]] > Sent: July-22-19 12:22 PM > To: Enhanced Machine Controller (EMC) > Subject: Re: [Emc-users] Rotary axis usage > > Real fast reply John, but does this video help? > > https://www.youtube.com/watch?v=d0ffiCekhpE > > Martin > > ________________________________ > From: John Dammeyer <[email protected]> > Sent: Monday, July 22, 2019 12:06 PM > To: 'Enhanced Machine Controller (EMC)' <emc- > [email protected]> > Subject: [Emc-users] Rotary axis usage > > I've run into a situation with the CAM file generated by MECSOFT AlibreCAM > appears to have a problem. I've asked this on the support group for > AlibreCAM but I think it's a more general question involving simultaneous 4 > axis milling where I write the G-Code myself. > > > N1 G17 G20 G40 G90 > (4th Axis Create Cylinder/Round) > N2 T2 M06 > N3 S20000 M3 > N4 G0 X-2.2788 Y0. Z1.664 A46.8 F0. > N5 G1 Z1.45 A46.8 F11. > N6 X-2.4983 Z1.4113 A46.8 > N7 X-2.5389 Z1.404 A46.3 > N8 Z1.4 A45. > N9 X-2.5388 A43.7 F14.7 > N10 X-2.4959 A43.2 > N11 X-0.0018 A43.2 > > > Effectively the feed rate on the X,Y and Z is 11 IPM or 14.7 IPM. But the > rotary axis is angular under LinuxCNC and measured in degrees per minute. > I believe that makes sense because the diameter of the part being rotated > determines the actual feed rate. So if the circumference was 14.7" and the > cutting speed is set at 14.7 IPM then the rotary axis should turn 360 degrees > per minute. > > But as shown in line N9 we have simultaneous motion on X and A but at > F14.7. > > Clearly if the diameter was such that the circumference was 29.4" then the > feed rate of the A axis would have to be half or 180 degrees/minute. > > Running the G-Code above sees the Z or X axis moving at the expected > speed. Watching paint dry is more interesting than watching the A axis turn. > But if I just do a G1 A360 F360 the motion of the A axis at 4.68 diameter > appears to be about the same speed as the X or Z horizontally. It also takes > exactly 1 minute to move 360 degrees at 360 degrees/minute. > > So how is this solved? How would the A axis know the diameter and be > able to translate that a request of F14.7 should really be F360 when Z is > being moved at the same time? Odds are I've configured the CAM software > wrong but if I was going to just manually write some G-Code that involved > simultaneous motion what would I do? > > The AXIS display shows 14.7 for speed. The Z is known. Is there something > missing so that the A axis actually gets a much faster rate? > > Thanks > John > > > > > > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users > > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
