In another life I read quantum physics. It was a walk in the park compared to comprehending all the permutations of different thread types. I have previously posted about the multitude of sizes, threads and finishes for the fasteners on this machine and now I’m at the stage of gradually reassembling the component parts back onto the mainframe I have discovered yet another thread type. The Villiers engine and the bolts holding the engine through support brackets to the frame as well as the clutch mechanism use BSCy (British standard cycle) thread at 26tpi* which I had-visually- assumed in my ignorance to be BSF (20tpi) and bought accordingly. Despite fixing many bikes in my youth and much to my shame I never realised that BSCy threads even existed. Apparently this thread type is used where constant vibration could loosen a courser thread. Anyway I’m not going to ‘spoil the ship …’ by using the rusty and badly corroded old nuts so, contrary to my previous post, I have once again had to order new ones online and in the meantime turn my attention to other assembly jobs.
*Footnote. Isn’t the computer wonderful. With the aid of a huge magnifying glass I counted 13 teeth over half an inch of the bolt thread and simply entered ’26 tpi’ into google and up came the answer –cycle thread. How did we manage before the internet ?
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