[SEL] drill sizes for 7BA clear and 7BA tap

[John Culp]

Not really. B.A. is British Association. A standard for small threads, 
below about 1/4". Dates back to the 1800s, but the dimensions are 
actually metric-based. The thread profile is much narrower than 
Whitworth. Details are online on a bunch of sites, some of which have 
already been cited.

Interestingly enough, the small screws on Mauser rifles are B.A., and 
the big threads on the barrel are Whitworth. The original machine tools 
Mauser Werke used came from England, and all subsequent Mauser 
licensees have stuck with the English thread standards.

If anyone needs any B.A. #1 x 1" cheesehead screws or hex nuts, let me 
know. I had to order a pretty good bunch from 
http://britishfasteners.com/ to meet their minimum order when I tore up 
the funny looking round, slotted nut on the barrel band of my 
Czech-built M98/29 Persian Mauser.

John

On Sep 24, 2006, at 8:12 AM, John Hall wrote:

> Try this site anytime you run into oddball threads---I use them at 
> work quite often.
> www.marylandmetrics.com
>
> Am I correct that BA threads are the same as Whitworth?
>
> John Hall


John Culp
Bristol, Tennessee, USA