I lucked out when I bought a bunch of whitworth tools from a local dealer and decided to through a huge 7/8W X 1W tube spanner into my pile just because it was whitworth. Turns out the 1W (1 1/8BSF) fit perfectly but was too long. I cut it in half and drilled a 1/2 hole through the side to slide a bar through and now that's it's job. It measures 1 33/64" just bigger than 1 1/2" sae.