engineering help on how to size BSW bolts please
Posted: Tue Apr 17, 2018 3:05 pm
Hi All
I have purchased on eBay some 1/4" whit bolts for the front seat mounting, I was expecting to get a head size that would fit a 1/4" spanner, on checking they fit a 3/16" Whit. and far to thin to go into the captive nuts ( I have bought longer bolts as they are going through a bracket to take different seats )
If you wish to check the advert it is eBay item number: 192244796002.
Was I incorrect expecting them to fit a ¼” Whit (5/16BS) spanner.
His reply below.
Thanks
Reg
hi Reg
Whitworth as with all bolts are measured across the bolt not the head
there are two head sizes for whitworth bolts
"whitworth" which is before the war and "British Standard Whitworth" after
to save steel in the war they dropped a head size by one bolt size so all the spanners would still fit
this is why some older spanners are now marked incorrect and latter ones have two sizes marked on each end and new spanners are marked as BSW
cheers
stephen
I have purchased on eBay some 1/4" whit bolts for the front seat mounting, I was expecting to get a head size that would fit a 1/4" spanner, on checking they fit a 3/16" Whit. and far to thin to go into the captive nuts ( I have bought longer bolts as they are going through a bracket to take different seats )
If you wish to check the advert it is eBay item number: 192244796002.
Was I incorrect expecting them to fit a ¼” Whit (5/16BS) spanner.
His reply below.
Thanks
Reg
hi Reg
Whitworth as with all bolts are measured across the bolt not the head
there are two head sizes for whitworth bolts
"whitworth" which is before the war and "British Standard Whitworth" after
to save steel in the war they dropped a head size by one bolt size so all the spanners would still fit
this is why some older spanners are now marked incorrect and latter ones have two sizes marked on each end and new spanners are marked as BSW
cheers
stephen