On Saturday 13 January 2018 00:25:26 Tom Easterday wrote: > We have been successfully using G76 for external threading on our > EmcoTurn 120P lathe for some time. We haven’t yet used it for internal > boring or threading. We have an application to make some internal Acme > threads in a cylinder. We have a right-handed solid carbide Acme (8 > TPI) threading tool. When I run the G76 (set up for internal > threading) it is apparent that the machine routine thinks the tool tip > is pointing up. It moves in but then moves down (rather than up) to > retract. > This is confusing Tom. From the video I'd assume the enco is a slant bed machine. So this s/b equ to a regular lathe, with the z axis rotated some arbitrary, might not be 90 degrees CCW as viewed from the tailstock end. All G76 values are positive except for I, which determines the internal/external toolpath. I s/b positive for an internal thread. From the video, the g76 toolpath looks correct IF the spindle is turning toward you, or CCW viewed from the tailstock. I cannot, from the video, determine which way the spindle is turning, but it looks like the tool tooth "top" is faceing us, which implies the spindle s/b turning CCW, normal IOW. This would cut the thread in the lower wall of the hole, and which looks correct to me,
> So with a left-handed tool spinning the spindle in the opposite > direction this would work, but we have a right-handed tool we want to > use. I am wondering if an external G76 would work? > I would need to fix > the tool retract at the end of the cycle (it goes directly up rather > than coming out of the work), Thats the only problem I see. > but other than that is something > inherently different? See youtube link below where I run an external > test tool path. > Thats not an external path to me, its proper motions for an internal thread. A positive I IOW. > I could also turn our tool upside down in the holder, but the flat > that keeps the tool from spinning is on the wrong side. We could grind > a flat on the other side of the tool but would rather not do that > unless there is no alternative. Is there some other way to get the > orientation correct? > > Youtube video of external threading toolpath with internal threading > tool:https://youtu.be/Rmt8W73Wd78 Still confused. If the top of the tool is faceing the camera, the path looks correct, but check your tools clearance when at the drive line, and fully into the hole. I broke a chip just this week because I used too much I. The back of the tool shank hit the back of the hole, flexing it so the chip dug in and snapped. Tool had a tapered shank, and I wound up turning the toolpost about 3 degrees CW to gain clearance. Thread worked fine. > -Tom > ---------------------------------------------------------------------- >-------- 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 > [email protected] > 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) 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 [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
