On Tuesday 21 July 2020 14:44:12 Robert Ellenberg wrote: > I totally agree that a silent failure mode (especially one that can > break taps) is bad news. Perhaps thankfully, we've gotten away with it > for a long time: based on the git history, the 10-rev overshoot limit > and this silent failure mode has been around at least since the 2.6 > days, maybe earlier. > > I have a few ways in mind to fix this: > > 1. Throw an error and abort motion if it reaches some threshold of > overshoot (say 90% of the maximum), or maybe if the position > tracking error exceeds some threshold. > 2. Check if the rigid tap motion + max overshoot exceeds the axis > limits (currently we check before adding the overshoot allowance, > which in theory could lead to motion past the soft limits) > 3. (optional) Tell motion what the expected spindle acceleration is > (via HAL pin), so that it can start reversing before it hits the > bottom of the hole (reducing the overshoot). Leaving this pin at zero > (default) would give you the current behavior.
Option 3 sounds like a great idea Rob, and it would/could/should be made to work with the G33.1 peck wrapper I hasn't published yet. I could even imagine 5 or 6 strokes, cutting air and programming that to achieve zero overshoot by actively adjusting the Z stop. Making it smarter than the average bear. > -Rob > > On Tue, Jul 21, 2020 at 2:17 PM Gene Heskett <ghesk...@shentel.net> wrote: > > On Tuesday 21 July 2020 13:09:16 andy pugh wrote: > > > On Tue, 21 Jul 2020 at 18:03, Robert Ellenberg <rwe...@gmail.com> > > > > wrote: > > > > 1. The rigid tapping cycle allows a hard-coded 10 revolutions > > > > > > > > <https://github.com/LinuxCNC/linuxcnc/blob/master/src/emc/tp/tc. > > > >c#L8 56> of overtravel beyond the nominal bottom of the hole when > > > > reversing direction. > > > > > > That feels like there should be an error message. > > > > > > "Maximum rigid tapping limit exceeded. And furthermore I have just > > > broken your tap" > > > > "Maximum rigid tapping limit exceeded. And furthermore I have just > > broken your $85 carbide tap" > > > > There, I fixed it for you. :( > > > > 10 turns is way too far. I cut air at least once to measure the > > turnaround (I have that stuff in my .hal file) and in what I have > > done, that has led me to set a personal limit of 2 turns. Taking a > > broken tap out of a valuable blind hole via EDM is a genuine PITA > > and I will do whatever it takes to avoid that. But, I would not > > uncouple the spindle from the tap either, killing the spindle drive > > ASAP instead, then one might be able to back the tap out of the > > hole with the spindle, salvaging the part so maybe the hole could be > > finished by hand. > > > > 10 turns, breaking the tap is the wrong thing to do. Shutting down, > > leaving it coupled before the tap breaks is the best thing to do. > > > > Cheers, Gene Heskett > > -- > > "There are four boxes to be used in defense of liberty: > > soap, ballot, jury, and ammo. Please use in that order." > > -Ed Howdershelt (Author) > > If we desire respect for the law, we must first make the law > > respectable. - Louis D. Brandeis > > Genes Web page <http://geneslinuxbox.net:6309/gene> > > > > > > _______________________________________________ > > 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 Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) If we desire respect for the law, we must first make the law respectable. - Louis D. Brandeis Genes Web page <http://geneslinuxbox.net:6309/gene> _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
