S I nce this is a wobbly thread, I'll put my 2 cents in. We had a fair size split case pump come in our shop that was mostly destroyed on the rotor assembly. Pulling the oil housing plugs , I noticed they had gaskets on them.with further inspection of size and thread pitch, we determined those plugs were of the British Standard Parallel pipe series of threads. Everything else was as metric as could be. That was certainly a first and a eye opener for me as in a global economy, keep machinery builds in an open mind! Don't assume anything!
Just for your information, pipe treads world wide use almost the same standards. National Pipe Tapered (NPT), National Pipe Straight (NPS)up to around 2". They are almost the same as British standard pipe with some exceptions like NPT/S 1/8" 27 as opposed to BSP 1/8" 28. Pipe internationally is based on ID in the inch or zoll in German and is only approximate, based solely on the manufacturer. The wall thickness of pipe is specified by its "Schedule". Interestingly, NPS, although American, is rarely used in the US, but it very common in the Metric world for air fittings. Please note, that when NPS is used, sealing is provided by a seal washer, not the threads, as in NPT.
Hey Sagehawk, we had something similar at work many years ago. We had hardware that my boss kept telling me it was 13mm threads. Well there is no 13mm threads. Long story short I finally figured it out with the Machinist Bible. It was a 1/2"-16 British Whitworth. My boss was really pissed he lost the argument!
One of the machinist I worked with used to be a wrench for a local Triumph/BSA dealer. When he retired he gave me all his Whitworth wrenches since I have an old Trumpet. They are very strange for sure!
Posted on Wednesday, March 22, 2017 - 12:08 am: A million years ago in California(1981) i promised my mom I'd do a top-end on her "new to her" Dodge Omni. It wouldn't make it over the pass on I-8 heading to Texas from San Diego.
I had a full set of SAE, Metric and BS Whitworth wrenches and still had to use a crescent hammer a few times. What a POS.
I had some experience with a few of those...what a PITA! Same, here, a favor for my mother...