Well it's working again. Probably had the arm apart 20 times. I found two nylon gears that had hairline cracks and were no longer fixed to the shafts.
Put it back together and discovered another pair of pinions that had the same issue. Once again mark up the shafts with the dremel, and then drill tiny holes in the body of the pinions and epoxy. And put it back together again. Wrong of course. I finally figured out that the surplus epoxy on the non-gear part of the pinions was interfering with adjacent pinions and gears that were very close. And I had yet another shaft backwards... There's a lot of wear in the system. But it is operational. I think when I build my real robot arm using all the different 3D printed harmonic drive solutions I'll set up a pair of joysticks to duplicate the armatron behaviour. Just for fun. Made Christmas Eve and Christmas day interesting anyway. John > -----Original Message----- > From: John Dammeyer [mailto:jo...@autoartisans.com] > Sent: December-23-21 9:12 PM > To: Enhanced Machine Controller (EMC) > Subject: [Emc-users] Complex 6 axis robot arm. > > I bought one of these well over 30 years ago. > http://www.autoartisans.com/armatron/SuperArmatron.jpg > > My sons played with it until either they were bored or it stopped working. > It went back in the box and they never told me the motor > no longer ran. > > I ended up taking it apart and disassembling the small 3V DC motor. Bend > clips back, pull off plastic brush assembly. Black greasy > gunk all over the armature and brushes. Once cleaned up and put back > together the motor ran but two of the joints were > problematic. I really didn't want to take apart the arm but I could see a > shaft turning but the gear not. > > When I did it burst apart and gears and gears mounted on shafts were > everywhere. Took a while to figure it out what went where. > Now I've used the Dremel to carve some grooves into the shafts and small vise > on mill to drill 1.15mm holes into the body of the > nylon gears which, I'm guessing due to age, had cracked. Almost looks like > the gears were molded onto the shafts but no splines. > > http://www.autoartisans.com/armatron/ArmDisassembled.jpg > > Anyway, a bit of 60 minute epoxy and now I'll have to wait 12 hours for it to > set good and hard and then the adventure of trying to > put it all back together. I know where it all goes now. > > All mechanical, one motor turns continuously, the joysticks engage six > different gears to create the joint motion. The complexity > reminds me of IBM Selectric typewriters I repaired as an IBM OPCE so many > decades ago. > > Now it's all done with computers. I'm not sure there are even people around > who could design something like this that is fully > mechanical. > > John Dammeyer > > _______________________________________________ > 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
