Today's Off Topic

I forwarded the picture of unusual bolts to an elderly friend and airplane builder, who was a machinist before he retired. He responded that he once worked for a company that built Jails and they used a lot of bolts that had a double countersunk heads. The holes were countersunk extra deep too accept the first head, then torqued down until the second (top) head broke off, then welded and ground flush. This prevented the inmates from removing the bolts.
Jerry

Sounds a bit like the current nut-bolt combination used for anti-theft on traffic signs.



Only difference is that it's the nut that breaks off.

They look like they work sort of like Huck bolts

There are also Counter-Snap screws for fixing squeaky hardwood floors. You screw them in and then the head breaks off below the surface, leaving only a small hole which can be patched.

snopercod said:

There are also Counter-Snap screws for fixing squeaky hardwood floors. You screw them in and then the head breaks off below the surface, leaving only a small hole which can be patched.

Click to expand...

Or buy cheap screws from Harber Fright and watch them do exactly that.....