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I've three older, used, 1 hp, 3450 rpm, Sears/Crafstman motors to choose from to run a used 10" table saw on a 110v power. None smell burnt.

If they are all in equivalent decent shape, will they perform the same?

If not, is it possible to deduce which will perform best, or do I need to test all three?

Two have a capacitor wart for start-up, the third is labeled as "capacitor motor".

Two are 115, the other is 115/230.

One is labeled 40 degC Ambient, another 40 degC Temp Rise, the third 50 degC Cont. Temp Rise.

1) Smallest motor, sleeve bearing:

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2) A bit larger than the smallest motor, sleeve bearing:

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3) Largest motor, ball bearing:

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The #3 motor having ball bearings will outlast the sleeve bearings. A ball bearing motor can be run closer to 115% of FLA (full load amps) with creating as much heat. The larger Frame usually provides more torque at the same amperage. Small motors like this are usually rated in peak horsepower / 746W of consumed power is called 1 horsepower. This calculation is usually at close to locked rotor so no true power is being generated, just consumed. To answer your question You might find the larger ball bearing motor has 20-50% more torque at 746W so it would be much more powerful than the other 2 motors.

  • Thanks. I don't understand the wiring diagram on the plate of Motor #3. imgur.com/nX7gCxX. The existing cord is old, very large diam (1/2", maybe 5/8"), and cracked, with only two conductors. Where should I connect the black, white and green wires in the new cord? – Merkle May 31 '16 at 23:12
  • Looks like I need to split open the housing to wire it properly. The cord has two conductors, pigtailed to two heavy conductors going into the "bottom" of the housing. After removing a service plate on the end of the motor, I see four lighter conductors attached to T4, T1 and 3. What happens in-between is a mystery. – Merkle May 31 '16 at 23:31
  • There should be a diagram on the cover plate, most of the time the 120/240 motors are parallel or series with the stater winding. (parallel for the 120 voltage series for 240) so we just to find T2 . normally 3 is tied to 2 and line on 1&4 for 240,,, 120 is 3&1 connected to one side 120, 2&4 are connected to the other this is a standard but best to check the name plate or inside the motor cover. I have only ever had 1 blow up and it was a cheap import 3 phase that the T leads were mis-labeled. – Ed Beal May 31 '16 at 23:53
  • Thanks. The link shows the wiring diagram. Didn't quite follow you, but ... I split the housing. The "black" lead disappears into the winding. The white lead is soldered to the thermal reset switch. After that, the wires get more complicated, but it is of no concern. I'll just hook up the white and black of the new cord the same as the old cord. I still don't know where to attach the ground. One of the bearings is pretty dry. – Merkle Jun 1 '16 at 0:16
  • The ground is attached to the motor frame. a little fresh oil in the bearings should free them up. – Ed Beal Jun 1 '16 at 13:00

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