I see what looks like the correct formulas on p. 18 of this document ; where are the incorrect ones?
On Wed, Jan 3, 2024 at 6:55 PM andy pugh <bodge...@gmail.com> wrote: > On Wed, 3 Jan 2024 at 22:01, andy pugh <bodge...@gmail.com> wrote: > > > This means that the large and small arcs are tangent to each other, > > which requires that their centres lie on a perpendicular line, and > > that in turn means that the arc centres of small and large arcs must > > be coincident. > > Close, but no cigar, it seems. > > There is an equation in an online document > ( > https://archiwum-bazakonkurencyjnosci.funduszeeuropejskie.gov.pl/file/download/587886 > ) > that isn't actually correct: > > x'= Dm/2×cosØ −2×e×cos(2Ø)+e×cos(4Ø) > y'= Dm/2×sinØ -2×e×sin(2Ø)+e×sin(4Ø) > > However, after getting hold of a pirate copy of the standard, it turns > out that it was only slightly wrong. This is what it should be. ( -+++ > not -+-+) > > x'= Dm/2×cosØ −2×e×cos(2Ø)+e×cos(4Ø) > y'= Dm/2×sinØ +2×e×sin(2Ø)+e×sin(4Ø) > > Plotted out this is very close to the shape that I had but differs by > about 30 microns at the worst spots. > > The good news is that this is very easy to convert to either XY > offsets for boring, or a radius for computed offset on a lathe as it > is already in terms of spindle angle Ø. > > > -- > atp > "A motorcycle is a bicycle with a pandemonium attachment and is > designed for the especial use of mechanical geniuses, daredevils and > lunatics." > — George Fitch, Atlanta Constitution Newspaper, 1912 > > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
