[ARC5] [Milsurplus] Question for Our U.K. Members

[WA5CAB at cs.com]

Dave,

John is of course correct.  The common sizes are 0BA through 4BA (in order 
of decreasing diameter).  If I recall correctly, the hex sizes, instead of 
being to the nearest convenient 32nd or 16th were calucalated from an obscure 
formula relating shear strength of steel used in wrenches/sockets to that 
used in nuts/bolt heads.  Apparently, the thread pitches were calculated in a 
similar manner.  This also applies to the larger BSF and BW (sometimes 
shown as BSW) fasteners (I used to own a lot of 50's/60's Land Rovers).  BA 
stands for British Association.  I forget what the full title was.  As far as I 
recall, there were no fine and coarse thead versions of the machine screws.

In a message dated 01/05/2012 09:15:07 AM Central Standard Time, 
jfor at quikus.com writes: 
> David,
> 
> Almost certainly not Metric.
> 
> Most British WW II (and into the 60s or 70s) used BA nuts and bolts.
> 
> http://www.britishfasteners.com/index.php?
> 
> for example, has size reference data. They are still readily available
> from many suppliers.
> 
> -John
> 
> ==============
> 
> 
> 
> >Your "Battle of Britain" aircraft set, the TR9D, used many metric
> >"cheese head" screws.  I need to replace most of them in this set,
> >but I'm having trouble sizing them.  Would one of you have the
> >dimensions and threads of the screws used on the cover and
> >the receiver shields?
> >TNX OM ES 73 DE Dave AB5S
> 

Robert Downs - Houston
wa5cab dot com (Web Store)
MVPA 9480