As a device to go to sleep I have lately been building motorbike components in my mind. Last night I was thinking of a better way to mount a jackshaft. I would machine the ends of black pipe to accept sealed 16mm I.D. ball bearings. Then mill a portion of the O.D. to receive a flat plate of about 3/16" thickness with rounded corners wide enough to mount U-bolts to secure it to the seatpost above and below the tube. Then a dog-point setscrew or 2 into the frame to prevent the jackshaft unit rotating. Insetting the plate into the tube wall would look better and allow a nicer weld bead. I am still playing with the Lawnboy 4 HP in a Cranbrook frame idea. It might get my COMET VST. Just too cold to do squat right now.