On Saturday 21 January 2017 04:28:00 John Morris wrote: > On 01/20/2017 08:30 AM, Robert Ellenberg wrote: > > On Fri, Jan 20, 2017, 9:22 AM John Kasunich <jmkasun...@fastmail.fm> wrote: > >> On Fri, Jan 20, 2017, at 07:46 AM, John Morris wrote: > >>> The manual for G33 spindle synchronized motion [1] reads, "It is > >>> an error if [...] The requested linear motion exceeds machine > >>> velocity limits due to the spindle speed." > >>> > >>> It seems that doing that actually doesn't cause an error, as > >>> demonstrated by the regression test in the top commit here [2]. > >>> Instead, the G33 command is happily executed with the axis > >>> velocity limited to its `MAX_VELOCITY` from the INI file, thus > >>> cutting threads with smaller pitch than specified in the K flag. > >>> > >>> Is this something that should be fixed, or am I reading the > >>> documentation wrong? > >> > >> I think it is a terminology thing. Where the manual says "it is an > >> error", read it to mean "if you do this, you made an error and all > >> bets are off", rather than "if you do this, LCNC will detect and > >> report it". > >> > > That's true, though I think we should warn users of errors we can > > detect as > > > early as possible, so they don't have to destroy a part to learn > > the significance of a line in the documentation. > > I also thought of these three possible intended scenarios pointed out > in this thread, and can think of valid arguments for each, briefly: > > 1. The manual says it's an error, and it's up to the user to avoid it > (status quo) > 2. The controller detects the condition, and informs the user > 3. The controller detects the condition, and compensates by adjusting > spindle speed > > Of course "spindle synched motion" most simply means to move other > axes by a specified amount with each revolution of the spindle. In > this case, the spindle shares some characteristics with an axis, since > the goal is to produce coordinated motion of a tool across the surface > of a workpiece. In coordinated motions involving the XYZABCUVW axes, > the TP will scale down the feed rate in order not to violate > constraints for any axis. > > Scenario 3 extends this thinking to scaling spindle speed to keep > within axis constraints. Aside from the theoretical elegance, I can > think of practical reasons, like having the same .ngc file produce the > same tool path on different machines.
A definite plus. > I'm going to take a look at Rob's implementation (related thread here > [1]). Thanks- > > John With my/our thanks John, bearing in mind that a vfd driven, multi-gear spindle is not, or hasn't been for me, as agile in time vs speed as the dc motors on my other machines. My G0704 can reverse from 2500 fwd to 2500 in reverse in 400 or 500 milliseconds. My vfd, although I do not yet consider it calibrated, will be 5 seconds or more from 500 rpm. I have not explored faster because my chuck is screw on. One of my first projects is to make a clamp on the rear of the faceplate that puts a death grip on the spindles flange just in front of the front bronze bearing. Then to transfer that lock to the faceplate, pin another clamp to the cleaned up faceplate hub. That shouldn't be a clothing catcher if I do it right. > [1]: > http://www.mail-archive.com/emc-developers@lists.sourceforge.net/msg16 >953.html > > ---------------------------------------------------------------------- >-------- Check out the vibrant tech community on one of the world's > most engaging tech sites, SlashDot.org! http://sdm.link/slashdot > _______________________________________________ > Emc-developers mailing list > Emc-developers@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-developers 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) Genes Web page <http://geneslinuxbox.net:6309/gene> ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, SlashDot.org! http://sdm.link/slashdot _______________________________________________ Emc-developers mailing list Emc-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-developers
