On 09/06/2016 07:24 AM, Gene Heskett wrote: ... snip > Thats no doubt true, but I've just found that the tapered thread I need > CAN be done with the G76 we have. Its not even an error if E is as long > as the drive line - tp_mm. If that value is exceeded, that should be an > error but in 100% of the cases where the drive line starts off the end > of the workpiece, it is of zero consequence because what it does is move > to the I position, and next extends the overshoot distance to the right, > cutting air, then it runs a taper the full length of the thread, air > included.
I checked the source for 2.7 and sure enough E is only checked for being negative: > double taper_dist = block->e_flag? block->e_number: 0.0; > if(taper_dist < 0.0) taper_dist = 0.0; so any E equal to 0 or greater is okidoki. > > Angle of the taper is UNK, but for my purposes, may even be slightly more > than what I was playing with before. Try to make E equal to the length of the Z move. rise / Run = tan(theta) so theta = arctan(rise / Run) rise = K, Run = E so theta = arctan(K/E) (BTW, NPT pipe threads are specified as a slope which is 3/4" diameter in 1 foot length, or 1:16, so making E 16 times greater than K should work for NPT.) The end taper path is designed to leave the thread at the end of the taper, so figure out where your final threading pass should be. This pass should be K deep into the material, but since this will have the pass leave the material and the end of the pass, add a K's worth to I to drive it deeper, then add your tool clearance to I. The Z length only needs to be as long as the thread and enough lead-in to stabilize the synchronized motion before you start cutting chips. Then lastly, set your start position by calculating back from the final pass numbers. > So please do not take away the E of G76. > > Any chance you could put a - sign in front of an S number to select the > spindle, so -s6 s1000 m3 would spin spindle 6 at 1000 revs? E is needed for end tapers. Andy and I are arm wrestling over D which is the only letter left for adding features to G76. I think there are also dot forms of G76, such as G76.1 available for other features. -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/ ------------------------------------------------------------------------------ _______________________________________________ Emc-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-developers
