On Sunday 21 March 2021 02:30:26 Chris Albertson wrote: > 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.
Motor heat, telegraphing up the shaft, will not be a problen as I intend to drive this one with a 3 phase stepper/servo. With the motor controller used, which has no current setting dipswitch array, the motor current is determined by the error between the input stepper count, and the feedback encoder on the rear of the stepper. So generally speaking, the motors temp rise is determined by the effort needed to maintain position. This is the newest generation of stepper drivers, many times more efficient than the common 2 phase drivers we've used since the first slo-syn motors came out 80 years ago. The slo-syn's worked under extreme pressures at 18,000 psi as thats what drove the Palomar pan and tilt camera mounts on the navy's Trieste when it made the one and only dive into the mohole in Feb 1959, that we filled with oil, put a rubber diaphram under the lid, and drilled a hole in the lid to let sea water in. We should have pulled a vacuum on it to fill it with oil as one of the two had an air pocket someplace so it let in enough water to push the diaphram down into the gears, chewing a hole in it, but that wasn't found until the post mortem, it worked just fine yet when they got back to the surface. As the bench tech building those cameras at Oceanographic Engineering, my fingerprints have been into the mohole along with Jacques Costeau and Lt. Walsh. Not by any preconceived plan, pure serendipity, just one of the BTDT's I can relate from my history of making electronics work for us. > 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 I'm not saying I won't have to make a metal hub, but I'll try this first. Thanks Chris, 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
