by JCS » Tue Sep 14, 2021 2:40 pm
“Perhaps someone can enlighten me as to what a 2BA stud is and my day will deemed fruitful”
O.K ……RollyTG………..
There seems to be some confusion regarding what I suggested for replacement studs on the Otter switch and also the general threading arrangements.
I was suggesting using both 2 BA brass nuts and studs and no steel, and the tap if supplied was to be a 2 BA taper tap merely to clean up the original threads.
The existing three set screws are almost certain to be 2BA. That falls in with the early 1950’s British motor manufactures convention on thread sizes, on the changeover from BSF to UNF. This encourages owners, and sometimes specialists to assume the smaller sizes are also UN/Unified.
Both before and after this change, studs, bolts and set screws under ¼ inch used BA threads, usually from 0 BA to 6 BA.
The exception to the BA below ¼ inch rule was that American Standard threads were used on ignition distributors and some other products made by Delco Remy and a few carburettors had the odd American Standard screws. These exceptions occurred on American designed products even before “standardisation” to Unified.
The BA (British Association) threads are similar to Whitworth in that the root and crest of the thread are rounded, the thread angle being only 47.5 degrees. The rounded root helps prevent, very usefully, tearing up in the thread. The 2BA is the most popular of the BA threads with 31.4 threads per inch, requiring a tapping drill size of 4.00 mm and clearance drilling of 4.80 mm. Unfortunately, one of the American Standard sizes is very close to 2BA and rips out the bottom of the threads.
The BA threads originated in the Swiss watch industry where they became a standard for watches. Only used in the USA for export tools, but used fairly wide in Europe and in the Electrical industry in England. Used quite extensively on top end cars particularly in fuse boxes and anchors for steering column shroud nuts and screws. Rolls-Royce and Bentley cars are full of them, including otter switches!
“Perhaps someone can enlighten me as to what a 2BA stud is and my day will deemed fruitful”
O.K ……RollyTG………..
There seems to be some confusion regarding what I suggested for replacement studs on the Otter switch and also the general threading arrangements.
I was suggesting using both 2 BA brass nuts and studs and no steel, and the tap if supplied was to be a 2 BA taper tap merely to clean up the original threads.
The existing three set screws are almost certain to be 2BA. That falls in with the early 1950’s British motor manufactures convention on thread sizes, on the changeover from BSF to UNF. This encourages owners, and sometimes specialists to assume the smaller sizes are also UN/Unified.
Both [u]before and after[/u] this change, studs, bolts and set screws under ¼ inch used BA threads, usually from 0 BA to 6 BA.
The exception to the BA below ¼ inch rule was that American Standard threads were used on ignition distributors and some other products made by Delco Remy and a few carburettors had the odd American Standard screws. These exceptions occurred on American designed products even before “standardisation” to Unified.
The BA (British Association) threads are similar to Whitworth in that the root and crest of the thread are rounded, the thread angle being only 47.5 degrees. The rounded root helps prevent, very usefully, tearing up in the thread. The 2BA is the most popular of the BA threads with 31.4 threads per inch, requiring a tapping drill size of 4.00 mm and clearance drilling of 4.80 mm. Unfortunately, one of the American Standard sizes is very close to 2BA and rips out the bottom of the threads.
The BA threads originated in the Swiss watch industry where they became a standard for watches. Only used in the USA for export tools, but used fairly wide in Europe and in the Electrical industry in England. Used quite extensively on top end cars particularly in fuse boxes and anchors for steering column shroud nuts and screws. Rolls-Royce and Bentley cars are full of them, including otter switches!