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    Re: Manufacture new Bygraves?
    From: UNK
    Date: 2009 Jul 9, 13:31 -0700

    Locking of two tubes is an easy engineering problem to solve.
    I have a set of small hole diameter measuring devices by Moore and Wright they 
    use the pinciple which is, I am sure, likeley to be used in the German 
    version; or will serve well anyway.
    Consider a threaded rod in a tube with a wheel on the threaded portion at one 
    end such that turning the wheel pulls the threaded rod in the tube.  At the 
    other end of the tube you have two holes in the side of the tube with two 
    hardened balls (for Ball bearings)inside the tube but poking out partially.  
    The threaded rod is made into an inverted conical taper where the balls are,  
    thus when the rod is pulled down the tube the balls are pushed outwards.
    This principle is how the inner tube of a Bygrave device can be locked.  The 
    tapered rod can push two rods or balls or any shaped form of side pieces 
    outwards against the inner tube, thus slightly bending it into an elipse 
    which will bind with the outer tube in which it rotates/slides and hence 
    locking it.
    Douglas Denny.
    Chichester. England.
    [Sent from archive by: douglas.denny-AT-btopenworld.com]
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