Spiral or Spline socket

[Papaw]

I have an Indestro/Duro hex socket set with a 1/4' drive set included. One of the sockets appears to be a 5/16 size socket with a spiral or spline rather than 6 or 12 point. What is the odd socket for?

The question came up in a Facebook discussion today.https://www.facebook.com/groups/709531912547503/permalink/819120544921972/?comment_id=820207501479943&notif_t=group_comment_follow&notif_id=1501528677330249
  It is an Indestro 1452 socket set. Alloy Artifacts doesn't  mention it.

[bill300d]

I've heard it called a radio nut socket. Back in the day radios, tv, and other appliances I think had these decorative type nuts on them, particularly their faces. Some people also think that they were to remove rounded over nuts.

[Papaw]

Yep. Mark Mathus replied on Facebook that it was for radio. After checking AA on New Britain, I found a Husky socket set that confirmed that. It was called "Special Knurl" and this type of socket was needed to remove the knurled nuts used on some radios of the time.

http://alloy-artifacts.org/newbritain-nonebetter-p2.html

[Plyerman]

Hah! That reminds me of the knurled screws used on early Leatherman multitools, and the special sockets needed to disassemble them.

Now I know where he got the idea from.

[mvwcnews]

The taper splined socket will also turn the brass terminal nuts associated with radio batteries of that era.  A PEXTO RADIO SOCKET SET with 1/4" hex drive shown on pg. 17 of the March 2006 MVWC Newsletter included one of that style socket.
As for the LEATHERMAN tool - that's another place where a small Vise-Grip comes in handy.

[Lewill2]

Or another Leatherman tool.

[Twertsy]

I have a set of Walden Nut drivers of that style.  Walden sold an entire nut driver kit for radios.