I didn't see a mention in Spruce; is it just tougher steel than 4130
or is it tubing with a pre-drilled bushing? - Mike
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Dear Mike,

Look under 'Bushing Stock.'

'Hinge Stock' is another name for plain, old-fashioned SAE 1020 mild
steel tubing, usually having a sixteenth-inch wall. You may install
bushings in the finished hinge if you wish but other means of
distributing the wear are to provide additional hinge points or to use
a hinge-pin (bolt; whatever) of larger diameter. If kept greased and
cleaned periodically, with the pins replaced when prudent, even
operating off a dirt strip it will be twenty years or more before you
can detect any wear in the barrel of the hinge itself.

-R.S.Hoover