I’ve been working on and off on my 3D Printed “OpenSlotCar” design for a while now. I have two areas that I want to improve before I turn the files loose. One of them is the setscrew wheels (the other is the process for molding the tires).
I had a bit of a break through on the wheels that I’m quite happy with.
The original wheels were just 3D printed with a “cross drilled” hole for a set screw. I advised threading the hole with a tap to reduce the risk of stripping the plastic out with the setscrew.
These wheels worked okay, but could only be tightened and loosened around a dozen times at most before the plastic gave up. It was also difficult to get them tight enough not to slip but not strip them.
The solution I came up with is very simple, and I believe would be useful for many other 3D printed couplings. Essentially, I took the wheel model and added a pocket that was sized to press fit a piece of 6mm OD brass tubing. I pressed the tubing in, then cross drilled it with a drill and tapped the combined plastic/brass hole.
This hoop of brass gives the screw a sliver of metal to grab onto and yields a much stronger joint than just the plastic threads.
This system provides a connection that can be really tightened down hard with a hex driver and grips the axle hard enough that it is very difficult to twist or pull the wheel straight off with your hands.