I came up with this while building my Cerberus. The rod ends are 3/8" ball bearings epoxied to M4 hex head bolts with JB Weld. The sockets are each made with 3 neodymium magnets epoxied to a 3D printed carrier. Teflon tape forms the bearing surfaces on the magnets. The dust boots are printed in Ninjaflex.
The joints are dry, have zero lash, and when there’s a crash against the print bed, they just let go instead of damaging anything.
Very nice. One possible suggestion: consider switching from Teflon to UMHW PE for your bearing surface. Friction is comparable, but durability may be better.
You can also frication weld the balls to the bolts. Clamp the ball in a vise with a piece of leather as padding. Put the bolt in a drill chuck, and spin at high speed and hold against the ball. Videos on youtube.
I’ve looked at friction welding. I may have to look again. My suspicion was that I’d have trouble achieving good concentricity. I really like a repeatable process.
You might get somewhat stronger than epoxy, but I any significant heat might mess up the ball-bearing surface and make it more vulnerable to corrosion. And this joint doesn’t really need a lot of strength.
@paul_wallich , exactly right. I tried all manner of heat and enchants for soldering, brazing, etc. They all destroyed the finish. Until I can do some kind of high tech vacuum brazing at really controlled temps, I’ll be happy with the epoxy.
Strength is not a huge concern. Accuracy and repeatability are.
The trick to soldering these balls is not getting the solder to stick to the ball but getting it to stick to the stud. If you choose a stud made out of brass you’ll have an entirely different experience.
