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Needed 1/8th inch Whitworth countersunk Allen bolts, 0.5 approx inches long

That's why I mentioned Airbus, threw me in this day and age.

He also told me that 10% of the Airbus is now laser printed.....

Seeing the wing tip close up, showed the engineering excellence. Thought the fact that the tip had been scrapped at the age that my current Ford Transit is, was also thought provoking..
 
I was once told by an instrument maker that even BA threads are the usual threads to use and odd threads for repairs as you can drill out a stripped even thread and rethread to the next odd size with minimum loss of strength.
BA is a metric thread, even though it was developed by the British over a century ago.
Cheers Andy.
 
My father was a model engineer. He used a lot BA screws and bolts, mainly in even sizes.

Earlier he used a lot of 2- 6 BA while building radios and TVs in the 50s and 60s.
 
Chris said:
As stated above, to fix end caps on my Sugden A48II amp, I need 4 of these. Supplies long since dried up over the counter in the Canaries. Any suggestions, please ?
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Do you have (at least) 1 sample surviving bolt that you can measure?

BA is the most likely, BSW is IMHO unlikely, BSF is possible, metric is a long shot. If you're really unlucky it's UNC or UNF (American, numbered sizes).

You need ideally a micrometer to measure the diameter, but a Lidl/Aldi digital vernier caliper would work well enough.

To measure pitch, you need a wide range of pitch gauges (which most people, including me, don't have).

You can also use dividers, set in the hollows of as many turns apart as possible. Count the threads, measure the divider spacing on your very best rule, and divide.

Alternatively, if you can take a macro photograph, from a decent distance to reduce parallax, with a good scale in shot (and ideally in the plane of the thread apex) you can measure the pitch by counting pixels in the resulting photograph.

BugBear
 
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