I would expect compensation to be on or off period (that is, not PER axis). I am curious why you expect it to look that way. Why would you expect the first move to position itself one cutter diameter lower than where the cut should be?
We are using a NGCGUI routine that was written by someone else. After modifying it to make a taper with depth-of-cut as a consideration (as opposed to plowing through material at massive depths ;-) we saw this odd angled move that we were not expecting. We then noticed that the unexpected location was exactly 1 tool diameter below were we thought it should go, and then noticed that there was a G42 in the code. One thing lead to another and here we are... I have been playing with G41, G42 trying to understand what the $%%@ cutter compensation means on a lathe. I think I am more confused than ever. But one thing is clear, I do not understand why G42 would cause that line to angle up like that, or more specifically why it would seem to be turn on on one move and then off on the next. Also, Also…I have very weird behavior in Axis when trying to set G41 (to just play with what the back plot looks like using each one). It complains that you can’t have G41 with G17 (plane). Ok, all well and good. This is why there is a G18 clearly in the file, but even though the program runs Axis does not switch to G18. I have to issue G18 at the MDI prompt. At which point G41 works. But, then Axis says, when I go to move the machine home that it cannot use G53 with Cutter Compensation on. Why? G53 is machine coord, who cares if cutter compensation is on? To add insult to injury Axis also shows G40 in it’s active G-Codes even though I can issue G18 and G41. There is some really strange stuff happening. At this point, my eyes have glazed over and I think my inclination is to just completely ignore G41/G42 from now on. G40 will be my friend. Ugh. -Tom > On Jul 2, 2017, at 6:32 PM, Stuart Stevenson <stus...@gmail.com> wrote: > > The motion I see in the link looks like I would expect it to look. Are you > expecting cutter comp on just the X axis or just the Z axis or both X and Z? > > On Jul 2, 2017 5:12 PM, <tom-...@bgp.nu> wrote: > >> I admit that compensation confuses me on a lathe. I have no idea if it is >> cancelling or changing - but why would it change? There is a single G42 at >> the beginning of the routine. The routine is simply cutting a taper (as >> can be seen by the steeper lines in the back plot) starting at >> CurrentDiameter and ending at X-End, Z-End. >> -Tom >> >>> On Jul 2, 2017, at 5:54 PM, Stuart Stevenson <stus...@gmail.com> wrote: >>> >>> Are you sure it is cancelling cutter comp or is it changing cutter comp >> to >>> the other side of the programmed path? >>> >>> On Jul 2, 2017 4:50 PM, <tom-...@bgp.nu> wrote: >>> >>> Yes, I do see different results, the line becomes horizontal rather than >>> angled. But my question is, why when cutter compensation IS on, are the >>> moves treated differently. By the way, even if we change the first G0 >> to a >>> G1, we still get the angled line. So, it isn’t G0 vs G1, it is simply >> that >>> the first move is lower than it should be (by the tool diameter in the >> tool >>> table) and the second move in Z causes X to rise to the compensated >> value. >>> How/why? >>> >>> -Tom >>> >>>> On Jul 2, 2017, at 5:29 PM, Stuart Stevenson <stus...@gmail.com> wrote: >>>> >>>> You SHOULD see different results. >>>> >>>> On Jul 2, 2017 3:46 PM, <tom-...@bgp.nu> wrote: >>>> >>>>> I don’t disagree but am failing to see the connection to my question…? >>>>> -Tom >>>>> >>>>>> On Jul 2, 2017, at 4:16 PM, Stuart Stevenson <stus...@gmail.com> >> wrote: >>>>>> >>>>>> It has always been my experience G40 cancels cutter compensation. >>>>>> >>>>>> On Jul 2, 2017 2:44 PM, <tom-...@bgp.nu> wrote: >>>>>> >>>>>> Why would G0 to a given location in one axis (X) differ such that a G1 >>>>>> movement in another axis (Z) causes the first axis to move? Let me >>>>>> explain... >>>>>> >>>>>> Attached is a screenshot of the back plot from Axis: >>>>>> http://bgp.nu/~tom/pub/G0G1.png >>>>>> >>>>>> The highlighted line is "G0 X#<CurrentDiameter>" >>>>>> >>>>>> However, if you look at the back plot that IS NOT the CurrentDiameter >>>>> value >>>>>> where it landed. It MIGHT be "CurrentDiameter - Cutter Compensation”. >>>>>> >>>>>> But then 2 lines down I move "G1 Z#<Z-Start>" and the line rises up >> to >>>>>> CurrentDiameter. That is, the move “G1 Z#<Z-Start>” is also >> causing a >>>>>> move in X to CurrentDiameter (when it should already be there - but >>>>> isn’t). >>>>>> Why is this? Why is the G0 move different from the G1 move? Or >> phrased >>>>>> another way, why is that first line at an angle rather than >> horizontal? >>>>>> >>>>>> According to the G-Code reference it appears both G1 and G0 are both >>>>>> affected by cutter compensation so they should be the same shouldn’t >>>>> they? >>>>>> >>>>>> -Tom >>>>>> >>>>>> >>>>>> ------------------------------------------------------------ >>>>>> ------------------ >>>>>> 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 >>>>>> Emc-users@lists.sourceforge.net >>>>>> 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 >>>>>> Emc-users@lists.sourceforge.net >>>>>> 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 >>>>> Emc-users@lists.sourceforge.net >>>>> 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 >>>> Emc-users@lists.sourceforge.net >>>> 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 >>> Emc-users@lists.sourceforge.net >>> 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 >>> Emc-users@lists.sourceforge.net >>> 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 >> Emc-users@lists.sourceforge.net >> 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 > Emc-users@lists.sourceforge.net > 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 Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
