Hi All,
Does anyone know what size screw thread is used on the securing bolt for the case.
I know it's not metric. is it BA BSF or something else?
Thanks
Andy
Does anyone know what size screw thread is used on the securing bolt for the case.
I know it's not metric. is it BA BSF or something else?
Thanks
Andy
If it is less than 1/4", could be BSF, larger are BSW...
BA, BSP, and UNC are not likely in British equipment.
BA, BSP, and UNC are not likely in British equipment.
BA is extremely likely in British equipment. It stands for British Association. We were just discussing the Quad II which is full of them, 2BA, 4BA, and 6BA.
BA size chart
The tpi figures are way odd, would need special taps...
Change over to whatever is easily available at your local source, if that is easy to do.
The tpi figures are way odd, would need special taps...
Change over to whatever is easily available at your local source, if that is easy to do.
Last edited:
As far as I'm aware, BA threads were common but not universal in british audio gear of the 60's -70's. BSF threads were also used to by some manufacturers, apparently in line with their field of use, such as tag strip mounts. BA thread is a scientific instrument and modellers thread that would be found in meters, test gear and precision gear generally but chassis assemblies were often held together with BSF and occasionally, even BSW threads were used with lockwashers to fasten items like rubber feet (bumpons).
I think it best to check the turns per inch (TPI) of any existing screws and compare BSF and BA threads from the appropriate wikipedia page articles on those threads or, for another example, see here: BA size chart and:BSW & BSF Threads
FWIW, counting thread TPI isn't so hard if you use a small screwdriver blade to count the "clicks" as you run it down a measured length of thread - easier than holding it steady enough to peer through a magnifier at least.
I think it best to check the turns per inch (TPI) of any existing screws and compare BSF and BA threads from the appropriate wikipedia page articles on those threads or, for another example, see here: BA size chart and:BSW & BSF Threads
FWIW, counting thread TPI isn't so hard if you use a small screwdriver blade to count the "clicks" as you run it down a measured length of thread - easier than holding it steady enough to peer through a magnifier at least.
BA thread is mostly used for model engineering. In the UK companies like Blackgates will stock a wide range of BA nuts and bolts