Greetings all; I am trying to put together a G76 wrapper that will let me do a clean cut, test the fit, and if it doesn't, decrement a value thats is added or subtracted from the desired thread OD and factored into the z_start point, to run it again until it fits.
I am trying to use some math to allow the usual variations in thread face angles, normally around 30 degrees for most threads to adjust the z axis start point. For a 30 degree example, sin[30]=0.5, but that with a #<_drive_zstart>=[2.0 +[#<_t_offset> * SIN[30]], according to the backplot, is too much of an advance. Nominally twice too much. What I want to get is a backplot that shows the start point of the threading motion follows the same up to the left angle as a normal G76 run shows so that the point of the tool continues to cut on its leading edge only while cutting the thread deeper and deeper until it actually fits. The threads I am getting with good 08ERA60 inserts sure have a lot of "hair", and I do have the tip of the insert level with the centerline. This hair, while it cleans up nicely with a die or a pass with the correct nut, totally makes trying to measure it a waste of time. Here is the gcode, without adding the looping yet, this needs editing the t_offset at the top of the file. ==================== % ( adding a couple new vars to aid in the cut, test for fit, adjust and ) ( wash rinse and repeat till the stop button is clicked because it now fits. ) #<_t_offset> = -0.7500 ( use this to adjust size! ) #<_p_offset> = 0.000 ( place holder ) #<_thread_od> = 9.525 ( starting value ) #<_thread_end> = -24 ( mm's obviously ) #<_q_angle> = 30.000 (degrees) G7 G21 (diameter mode,mm mode, g20=inch mode) S250 ( diddle this stuff if inches as below) (#<_tp_mm> = 1.00) #<_tpi> = 24 #<_pitch> = [1.000 / #<_tpi>] #<_pitch> = [#<_pitch> * 25.4] (needs mm's) #<_thread_od> = [#<_thread_od> + #<_t_offset>] ( from thread_OD set drive xline ) ( set drive line OD 1st) #<_drive_xline> = [#<_thread_OD> + 1.5000] ( a bit large for mm's, works for ext ) #<_p_offset> = [#<_t_offset> * SIN[#<_q_angle>]] (sine of 30? degree angle) ( constrain this #<_p_offset> to be lt #<_pitch> either direction ) o150 WHILE [#<_p_offset> lt -#<_pitch>] #<_p_offset> = [#<_p_offset> + #<_pitch>] o150 ENDWHILE o151 WHILE [#<_p_offset> gt #<_pitch>] #<_p_offset> = [#<_p_offset> - #<_pitch>] o151 ENDWHILE ( set z far enough away sync is good for startup accel wibblies ) #<_drive_zstart> = [2.0 + #<_p_offset>] ( assumes mm's, too far for inches ) #<_z_end> = [#<_thread_end> + #<_p_offset>] ( 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>=[0.8 * [#<_pitch> / 0.866]] (debug, kpp=#<_kpp>) ( set threads OD, drive_line minus i ) #<_i_cut>=[0.000 - [#<_drive_xline> - #<_thread_OD>] - 0.01] m3g4p1 (start spindle, wait for speed) g0x41.1 ( clear armstrong bolts spinning base ) g1f450 z#<_drive_zstart> g1f250 x#<_drive_xline> g76 p#<_pitch> z#<_z_end> i#<_i_cut> j0.25 k#<_kpp> r1.6 q#<_q_angle> h5 e0.25 l2 ( leave it where it started from ) g1f450 x#<_drive_xline> (but out of the way for test fits) g1f650 z#<_drive_zstart> m5 g1f650x41.1 (back it out of the way to check screw fit) g0z150 m2 % =========== Thanks all. 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-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
