No Rod, I didn't miss anything. My calculations do in fact arrive at the same 5520 rpm with a 3450 rpm motor. I was a bit incredulous that the jointer originally ran at only 2720 rpm. That is pretty slow--even for babbitt bearings. But with only a 1/3 hp, 1750 rpm motor, a larger motor pulley would reduce cutterhead torque as rpm's increase. So, maybe 2720 rpm was the factory's optimum spec.
As I suggested previously, a 3" pulley on the new 3450 rpm motor would give a very decent 4140 rpm cutter speed.
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