Old socket id ?

[ganymede]

Anyone recognize these ?
They are 1/2 inch drive 4 pt. and the only markings are in the pic....

 

[Flatintoone]

Duro or Indestro

 

[ganymede]

Really ? Not dis-agreeing but I should have noted that the drive end is square too, not hex.

 

[Gmonkee]

Duro did both square and hex drive. Square is a lot harder to find as it came in more expensive sets in its day.

 

[ganymede]

I looked at the Duro section of Alloy artifacts and you guys are right. They are there!
Thanks !!

 

[930dreamer]

This "D"-like trapezoid symbol had been assumed to be an identification mark for Duro, an assumption that was confirmed by an illustration in a 1939 Duro catalog. The catalog shows an illustration on page 40 of a "Special Carbon Manganese Steel Socket", with the two trapezoid symbols clearly visible on either side of the size marking. We'll refer to this symbol in the text as the D-Trapezoid logo for ease of reference.

Apart from the markings, another difference from the (likely earlier) Indestro sockets is that the knurling on the Duro sockets is now a very fine cross-hatch, giving them a more refined appearance. The coarse knurling on early sockets was probably intended as a functional feature, to allow the socket to be turned easily by hand, but later evolved to a more decorative role.

Although these sockets are marked only with the D-Trapezoid and size, the 1939 catalog shows the model numbers that were used for the series. The numbers have the form "99xx" where "**" is the size in 32nds, so for example model 9924 indicates a 3/4 size. The square and double-square broachings are identified with an appended "S", e.g. model 9920S for the 5/8 size.