I have been doing some careful measuring of the krag screws this is what I have found up to now .. The screw pitch it 26 threads per inch witch is a British standard for tubing and bicycles the thread diameter is .180 that doesn't match anything British american or inerpalnitary If you know where this particular diameter originated  I would like to know ... the thread high from the root to the crown is .018 witch translate to a pitch diameter of  .5 this means the threads are short and square on top ... this was done to save ware on the taps and speed up production it is only used on threads where high tensile loading will not be expected so who came up with the bolt specification ??? 

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