Nut Traps

When I started designing R2 parts I needed a way to keep the nuts that hold various assemblies together in place while the bolts were installed and tightened.

The result was a 3D printed nut trap, or in the case of the battery boxes, a nut trap that was printed as part of the box shell.

I started out using square nuts, It was easier to design and I thought it would be easier to file the inside edges of the trap if it were slightly too small for the nut. At least that's the reason I can think of now :-)
 As Far as I know, it was never necessary!

Over the years, I've gotten a few reports that the bolts , mostly in the foot drives, but sometimes in other locations, have shaken loose and fallen out. The foot drive bolts install from the underside of the foot so gravity is working against you.

There is a solution, Hex Nuts are available with a Nylon insert specifically for high vibration environments. That's not an option for Square Nuts. I designed a 3D printed Hex Nut Trap for my Chopper Foot Drives.

I'm already 3D printing more things than I have printer capacity for so I thought I'd try a CNC machined nut trap instead!
Here's an installed example of my first version of the design.

I converted the mounting posts to holes that match the 3mm filament I use with my printers. Then I realized that the critical alignment issue with the nut trap is that the nut's center and the mating bolt center have to line up. I had used 4 posts on the 3D printed traps for strength. That's not an issue with the CNC nut traps.

To install, you put a nut & bolt into the mounting hole and use either the nut, or the head of the bolt (they are the same size) to align the nut trap. Just make sure you put it on the correct side. Flood the joint with Sci-Grip/Weldon  #3 for a solvent welded joint. If you are really worried about the nut trap breaking free (that won't happen if you have a good solvent weld joint) or the nut trap moving while it's being glued, you can thread a piece of filament thru the hole.
I revised the production version of the CNC Nut Trap so it only has one hole and I'm removing all but one hole from the mating tabs where the Nut Traps are installed. Fewer cuts means faster cutting time for the parts.