Thread: Small machine shop job

From the assembly drawing, it's not clear how the plastic is held captive. Looks like it could slide off the bronze bush? It might be optimistic to expect the bronze to wear before the plastic. What's the application? Would it be possible to use additional rivets or whatever, to get better wear resistance? If you really need the hex socket (rather than say a screw slot), modifying an Allen screw to make the shoulder bolt suggests itself.

Good luck,
Jordan

It's a pivot point, so I can't put more rivets in there. You're correct, there is nothing to stop the plastic sliding off in the original images. Here's another one that might help (apologies for the quality):



As you can see, the plastic structure will hold itself in place and I need to replace the rivets with the shoulder bolt/barrel nut fitting in pairs.

The hex socket isn't strictly necessary. It's probably the best option but obviously trickier to machine unless modifying an existing bolt as you say. A straight screw would work too. I'd loctite the bolt in and only remove it if necessary so it wouldn't need much torque applied on the head. A small simple tool for field repairs would be ideal, that's why an allen key would be best.

If the bronze bush were retained in the plastic part, it would wear only on the bolt, as you want. But how to do that? I see plastic parts are often assembled with metal thread screws that go into threaded bushes. These bushes are knurled or serrated on the outside diameter, and pressed into the plastic. The roughness of the knurl bites into the plastic and prevents movement. Could be you need to do something like that with yours.
Jordan