28-12-2019, 07:11 PM
I have just located a Christmas present from 1951! "Drawings and Diagrams for the Metalwork Class". On page 12 are the instructions for drawing a Whitworth bolt & nut. The book is too thick for my scaner, so I will try and describe the formula.
Dimension across flats = 1.5 + .125 Diameter of bolt. Thickness of bolt head = .88 Dia. of bolt. Thickness of nut = Dia. of bolt.
The dimension across the Points of the bolt head is 2 X Dia. of bolt, the inference being that the origional formula was worked out to allow standard round stock to be used, i.e. make 1/2" bolts from 1" stock, 1/4" from 1/2", etc.. I presume this is for the origional large headed bolts, not the later ones that share spanner size with the next size down B.S.F.
Dimension across flats = 1.5 + .125 Diameter of bolt. Thickness of bolt head = .88 Dia. of bolt. Thickness of nut = Dia. of bolt.
The dimension across the Points of the bolt head is 2 X Dia. of bolt, the inference being that the origional formula was worked out to allow standard round stock to be used, i.e. make 1/2" bolts from 1" stock, 1/4" from 1/2", etc.. I presume this is for the origional large headed bolts, not the later ones that share spanner size with the next size down B.S.F.