[Shop-talk] Locking Hinge?

[David Hillman]

    I have a shop project ( <-content ) I want to build, but I need a pair 
of hinges for it.  It seems like I should be able to find something 
similar and repurpose it, since my requirements are not overly-specific, 
but I can't.  I may not be looking in the right places.

    I need to join two elements, let's say 1" square steel tubes, although 
that's negotiable, end-to-end, like the bones of a human arm ( pretending 
the radius and ulna are one bone, for the moment ).  The key is, when 
extended, I need it to lock automatically ( manual release is fine ).  I 
think I could build it, if necessary, but first, can I buy something like 
this?  Doesn't need to be massively strong, say, 200 pounds load would be 
very safe.  90* bend would be nice, but anything more than 45* could 
probably be made to work.

    McMaster and other typical sources don't seem to have anything, but 
again, I might be missing it.

    Thanks for any brain storms you might have.

--
  David Hillman