There are sockets for square headed bolts & nuts, but in a pinch a 12-point socket will do. The internal angles are wrong (150* instead of 90), but if high torque isn't required ... they "will do".

I recently used one & it was a little frustrating to find the right size socket. So I did the math to find which socket to use for which square. (Actually, I drew them in CAD & took the dimensions.) There is a really surprising conversion: the square size in inches times 32 is the socket size in mm. E.g., a 3/8" square & a 12mm socket. The socket will be a bit oversize (2.4%), making the fit even worse than it was with the wrong angle, but in a pinch it will do. Try the next size down, to be sure (15mm fits 1/2" square better than 16mm).

Actually, there is a better conversion to imperial sockets: 5/4 times the square size (5/16 for 1/4 square, etc). Only 1.6% oversize. But unless you have sockets in 1/32's it only works for 1/4's square sizes (1/4, 1/2, ...).

"32" is the only thing to remember.

I recently used one & it was a little frustrating to find the right size socket. So I did the math to find which socket to use for which square. (Actually, I drew them in CAD & took the dimensions.) There is a really surprising conversion: the square size in inches times 32 is the socket size in mm. E.g., a 3/8" square & a 12mm socket. The socket will be a bit oversize (2.4%), making the fit even worse than it was with the wrong angle, but in a pinch it will do. Try the next size down, to be sure (15mm fits 1/2" square better than 16mm).

Actually, there is a better conversion to imperial sockets: 5/4 times the square size (5/16 for 1/4 square, etc). Only 1.6% oversize. But unless you have sockets in 1/32's it only works for 1/4's square sizes (1/4, 1/2, ...).

"32" is the only thing to remember.

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