On Monday 06 August 2018 05:18:31 andy pugh wrote: > On 6 August 2018 at 03:36, Gene Heskett <[email protected]> wrote: > > Tool paths (corrected) are I assume to be the nearest of the 8 > > positions, or are those actually calculated from data in the tool > > table (and fussed about if obviously wrong I hope. > > Tool radius correction is based entirely on the stated tool > orientation in the tool table. > It take no account of the stated front and back angles. > If you want an orientation 2 tool with the cutter flanks pointing back > in to the work then Axis will cheerfully render that for you while at > the same time the motion planner will do radius compensation for an > orientation 2 tool. > > The tool controlled point can only be at 9 positions relative to the > centre point of the tool tip radius. This has very little to do with > the flank angles. It is more related to which quadrants of a notional > full-circle tool are in use. > For example orienation 2 (right hand facing and turning) expects to be > touching at 12-o-clock when moving purely in Z and at 9-o-clock when > facing in X. If moving in some combination then the tool will be moved > a little bit closer to the work to compensate for the gap between the > controlled point and the tool tip that exists between those two > tangents. > > For the vast majority of lathe work cutter comp is not important. The > positions of shoulders and absolute diameters are unaffected. Tapers > will end up a little fatter than drawn and both external and internal > fillets will have extra material. The latter vary rarely matters, and > the former normally seem to need some tweaking-to-fit anyway, so I run > with cutter-comp turned off nearly all the time. > If I was machining accurate spheres then things would be different.
I was thinking in terms of carving the example/lathe pawn. None of the shown positions can carve it exactly, the best you can do it to steer it ccw enough that the side of the chip clears for all motions, and ignore the cutter comp. And I have discovered there are two versions of that pawn in the wild, the 2nd one looks to have been generated by a cad proggy but it does know about looping better than the original. It would take a bit longer but with its thinner cuts, the spindle revs could be setup as CCS mode, gaining back some of the lost time. Both make good practice at cutting air, but I've never actually made one. :) -- 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
