On Sunday 20 January 2013 00:02:02 Gene Heskett did opine: Message additions Copyright Sunday 20 January 2013 by Gene Heskett
> Greetings all; > > Has anyone cut any threads with g76 lately? > > I fired off a routine that 4 months back worked great, carving a 1/4-28 > thread for me several times last fall. Tonight, without any changes in > the .hal file that would affect threading ops, still set to make a > 1/4-28 SAE thread, and it came out at about 24 tpi. And I haven't a > clue. My encoder still has 39 slots. Etc, etc. I am on the bleeding > edge development branch. > > If someone could go cut a thread with this 2.6 code and check it for > true tpi, it might help me find whatever dumb effect I've put into this > in my spindle servo tuning. > > Thanks folks. A PS of sorts here. I just recalled that I had changed the servo-thread to run at 2khz a couple weeks ago. This of course doubles the capture rate of encoder.capture.position. Could this be why the threads I tried to cut were coarser than I expected? If that scales directly, then I should have gotten 14 tpi threads, but they were about 24 tpi when set for 28. That is nowhere near a 2/1 error. So that doesn't grok at all. Here is that routine: % g7 s100 ( all measurements in inches, set thread pitch ) #<tpi> = 28 #<pitch> = [1.000 / #<tpi>] ( set threads OD ) #<thread_OD> = 0.250 ( from thread_OD set drive& retrace diameters ) ( set drive line OD ) #<drive_line> = [#<thread_OD> + 0.060] ( set z far enough away sync is good. -0.1 leaves .2" for startup accel wibblies ) #<zdrive_start>= -0.1 ( ending point of thread at first pass, Q will advance it! ) #<zend>=-0.503 ( calculate this K from pitch ) ( set k, peak to valley of std USS/USF thread format = pitch/0.866 -10% clipped from peak and valley ) (#<kpp> should=0.032993, debug print it) ( so I want to use 80% of pitch /0.866 according to the Handbook) #<kpp> = [0.8 * [#<pitch> / 0.866]] ( set threads OD, drive_line minus i ) #<i_cut> = [0.000 -[#<drive_line> - #<thread_OD>] - 0.003] g1f26 x#<drive_line> g1f26 z#<zdrive_start> m3 g76 p#<pitch> z#<zend> i#<i_cut> j0.005 k#<kpp> r1.7 q29.5 h2 e0.015 l2 ( leave it where it started from ) g1f26 x#<drive_line> ( but move it out of the way of gages ) g1f26 z[#<zdrive_start> +6.00] g1x0.000 m5 m2 % ============================== I will change the servo-thread back to 1 kilohertz and retest tomorrow. Cheers, Gene -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) My web page: <http://coyoteden.dyndns-free.com:85/gene> is up! My views <http://www.armchairpatriot.com/What%20Has%20America%20Become.shtml> Tact is the art of making a point without making an enemy. I was taught to respect my elders, but its getting harder and harder to find any... ------------------------------------------------------------------------------ Master Visual Studio, SharePoint, SQL, ASP.NET, C# 2012, HTML5, CSS, MVC, Windows 8 Apps, JavaScript and much more. Keep your skills current with LearnDevNow - 3,200 step-by-step video tutorials by Microsoft MVPs and experts. ON SALE this month only -- learn more at: http://p.sf.net/sfu/learnmore_123012 _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
