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Old 03-16-2007, 09:57 PM
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Before you screw around with the treadle and the linkage, you need to reduce the ratio between the top pulley on the sewing machine and the bottom pulley on the clutch motor. The pulley on the clutch motor is probably held on with a large nut on top of a lock washer and a serrated washer. Pulleys are a standard item at hardware stores. The only thing you need to know is the shaft diameter and the keyway. ( both are standard for the shaft size, so remember the shaft size, which is probably 1/2") If the ratio is 1 to 1, reduce it to 3 to 2 (3" on top and 3" on the bottom to 3" on top and 2" on the bottom) That will reduce the speed of the machine 33 1/3% all through the speed range. Then you have to change belt sizes. To compute the correct belt size, measure the distance between the center of the shaft on the sewing machine and the center of the shaft on the clutch motor. Say that's 16". Double that, making it 32". Then add 1/2 the circumference of the top pulley times 3.1417(pi) to 1/2 the circumference of the bottom pulley times 3.1417(pi), and add them together. If the top pulley is 3" in diameter, that measurement is 4.7125. If the bottom pulley diameter is 2", that measurement is 3.1417. 30" plus 4.7125, plus 3.1417 equals 40.8542" The belt you need is a 3L410. 3/8" wide by 41" in outside diameter. Also available at the local hardware store. That will solve your speed problem, and when you have more experience, you can change the ratio back to a faster speed.
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