I use a reamer to make accurate holes in 3D printed parts. You can fudge the hole size all you like but you never get a perfect fit. Same with threaded holes. I print the threads but clean them with a tap by hand
If you want a perfect D-hole, print an undersized hole, ream it on the lathe or drill press then place the saft in the hole and fill the gap with JB-Weld. (put something on the shaft to keep epoxy from sticking) That said, my preference is to make metal hubs and to print the outer rims of gears and pulleys then epoxy the hub to the ring. The holes on printed pulleys always fail. Maybe because the motor gets hot but the holes seem to enlarge over time. 3D printed parts usually do require some hand work to finish. It is not unlike making parts from metal castings. Usually there is some machine work required On Sat, Mar 20, 2021 at 9:14 PM Gene Heskett <ghesk...@shentel.net> wrote: > On Saturday 20 March 2021 21:21:56 andy pugh wrote: > > > On Sun, 21 Mar 2021 at 01:12, Gene Heskett <ghesk...@shentel.net> > wrote: > > > It seems to me there ought to be a std math rule for that, but I've > > > not found a reliable reference. > > > > Why do you think that? Surely the manufacturer can make any flat that > > they want? > > This is true, but most of this stuff has a best practices doc buried > someplace on or in this planet. > > > I would measure the actual shaft (flat to rounded opposite curve) then > > dimension my sketch to that actual number (my printer shrinks holes, > > so I wouldn't make it any tighter deliberately) > > So does mine, if I want a 8mm bolt hole, I draw an 8.25mm,but a bar 100mm > long measures 99.8. Doesn't coorolate all taht well. > > Thanks Andy. Take care and stay well. > > 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) > If we desire respect for the law, we must first make the law respectable. > - Louis D. Brandeis > Genes Web page <http://geneslinuxbox.net:6309/gene> > > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > -- Chris Albertson Redondo Beach, California _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
