Who Made My Socket - A study in Socket Traits and Identifiers

This study will be an ongoing effort to identify key socket manufacturers dating from approximately 1910 through around 1950.  Speculation abounds regarding the source(s) of sockets, socket blanks involving key players such as Sherman-Klove, Milwaukee Tool & Forge, Duro, Indestro, Truth and many others.  We will attempt to identify suppliers, to whom sockets were supplied, and approximate timeframes where sources transitioned to another supplier and/or internal production.  The first thing we will do here is attempt to explain the differences in broach types.  The key types we will be studying in this effort will be stamped sockets, hot broached sockets and milled sockets.  We are going to focus mainly on external markings and date codes, and broaching methods.  In terms of broaching methods, we will attempt to hone in on how the different manufacturers "finished" their sockets after broaching.  Did they simply broach and ship, leaving much evidence of the method?  Did they mill the remaining chaff from the hot broach process leaving the socket clean and nicely finished?  Is there evidence of "chatter" in the broach?  and so on.

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The first thing we need to do is clarify what is meant by the broaching terms.  We will begin with stamped steel sockets.  This socket style is readily identified by thin socket walls and their obvious source of simple steel sheets, pounded with a stamp to form the socket tool.  Here are 2 examples, one bearing the Mossberg triangle M, and one bearing the Ray stamp.

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Cold Broaching (Thank you to MSHAW for this description!)  This socket shows the groove at the bottom of the hex and the pre drilled minor diameter typical of cold broaching. In this case the pre drill was oversize truncating the interior points of the hex. Also the groove at the bottom of the hex was not large enough and some burrs are still attached. Also notice the "blowout" of the square opening typical of one pass cold broaching. 

Bob Cat branded tools were marketed by Hinsdale and appear to have been available for a brief period in the early thirties.  This socket is believed to date from between 1930 and 1933.

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Here we will present examples of Machined sockets.

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Here we will present examples of Hot Broached sockets.