Subject: Whitworth Bolt heads

From: [email-masked] (Randolph Lee)
Date: Thu, 05 Dec 1996 10:58:33 -0400

>From  Page 4.11 in the new 3rd edition of Tubal Cain's "Model Engineer's
Handbook" (see TEE in the FAC for pointers to web site for ordering)

Old Whitworth (where D = Nominal Bolt Dia in inches)
Across Flats = 1.5D+ 1/8"
Across Corners = 1.55  x the Across the flats dim.
Nut Height = D
Bolt head height = 7/8 X D
Locknut thickness = 0.5 X D

He also says "..... prior to about 1939 most nut and bolt heads on Steam
engines would have been to the then 'Standard Whitworth' dimensions, though
British Standard Fine' hexagons were used in congested areas of medium and
large size diesel and gas engines - on cylender heads and bearing caps
especially. .... The BSF hexagon was, usualy, that of the next smallest
size of bolt - e.g. 1/2BSF fits a 7/16 Whitworth spanner. From 1941 onwards
the 'old Whitworth hexagon was phased out, simply to save metal during the
war, and both BSW and BSF bolts used the same BSF hexagon sizes."

~R

Randolph Lee
Windshadow Engineering