These aren't hex keys, what are they?

[damon18]

Probably showing ignorance, but I found these among a big pile of allen wrenches I was sorting for size.

Thought torx at first, but the points are flat and extend the full length of the tool.

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[RTM]

Spline? Drive tool?

Ive got a couple of tiny ones, think that’s the name on them.

 

[senlow]

Bristol Spline Drive Wrench.

 

[damon18]

Googling Bristol Spline Drive Wrench I saw a mention of these used for Ham and vintage radios.

I guess it's a specialty fastener I just haven't run across.

The biggest one I have is 1/4 inch or less, too much smaller. None of them have size markings since the splines are full length with no flat sides.



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[Fedwrench]

Ribe.

 

[cvairwerks]

Bristol splines as mentioned before. The come in both 4 and 6 spline, depending on size. The allow more torque on the fastener with a lower chance of camming out.

 

[JohnTools]

I thought Ribe on first look.

But would need dimensions to be certain.
There is also Polydrive as used on VW

 

[KnurledNut]

Definitely Bristol keys...

 

[minke]

Googling Bristol Spline Drive Wrench I saw a mention of these used for Ham and vintage radios.
...

I've got a few WWII ARC-5 aircraft radios that use splined keys like that.

 

[ricleh]

IBM Selectric typewriters used Bristol spline fasteners. The IBM repair kit for the typewriters had the Bristol spline keys.

 

[nadogail]

Bristol wrenches. I first encountered them in 1961.