Yeah, I was just curious about the history behind it. I have seen the sawblade arbor size debated before, but never really a solid explanation for one over the other. IF there is no technical reason for why 1-1/4" arbor size was selected, I wonder if perhaps Shopsmith had a plan to share the same arbor between a sawblade and another cutter such as for shaper operations? In fact, this probably makes sense in the UK case of 30mm arbor size. I see a lot of commercial multitool (table saw, sliding table saw, jointer, planer, etc.) units in Europe, such as Felder. I would assume these units could share arbors between sawblades or shaper cutters, so a common arbor between cutters may make sense. I believe 30mm bore (arbor) cutters are available over there. Just a thought...
At the end of the day, it may well be as arbitrary as one manufacturer chose a different size arbor to try to lock out customers from using another company brand sawblade, etc. OR for safety reasons - I have heard arguments that the newer 12" miter saws went with 1" arbors to be non-standard so that someone wouldn't attempt to put a 12" blade on a 10" saw by mistake (how could someone possibly do this and get the blade to turn?).
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