What are these called?

[anwat]

After wasting a half hour on the internet trying to figure out what these are called, I give up...they fit under your bolt head and can be wired to prevent it from backing out. I only have the 5/16 left and I can't find anyplace to buy more.

 

[Babaganoosh]

I have always referred them to as safety wire nuts.

 

[anwat]

That brings up the real nuts drilled for safety wire. I tried safety wire washers, and that's not it either. I don't think they would be enough to hold a preload, although the head of the bolt is pretty tight in the little cup. I think they are more for stuff that you don't want to loosen substantially.

 

[tarussell]

Years ago I heard a machinist refer to them as “wire retaining-nut covers” - they were considered obsolete and not trusted as much as the bolt heads being drilled.

 

[Babaganoosh]

That brings up the real nuts drilled for safety wire. I tried safety wire washers, and that's not it either. I don't think they would be enough to hold a preload, although the head of the bolt is pretty tight in the little cup. I think they are more for stuff that you don't want to loosen substantially.

Didn’t even realize it wasn’t really a nut.