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enter image description hereI have a Harbor Freight drill press 1-1/2 hp, running on 120 volt, capacitor start.

Is it possible to run CW & CCW rotation, using a DP-DT switch?

Motor has four wires coming out of it, all with color and numbers. black #1/gray #2/red #3/yellow #4

The picture is from the motor, if this is possible please show the wiring diagram. Thanks.

enter image description here

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  • \$\begingroup\$ Do you have a datasheet or even a part number for the motor? \$\endgroup\$
    – user199402
    Jun 20, 2019 at 16:28
  • \$\begingroup\$ Since this is a dual-voltage motor, there must be a diagram that shows the two voltage connections. That may have enough detail to help determine if the motor can be reversed and how to do it. You will need to determine how the capacitor is connected. \$\endgroup\$
    – user80875
    Jun 20, 2019 at 19:13

3 Answers 3

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As the motor is capacitor start, the answer may be yes, if the four wires give you access to the main and start windings.

Try starting the motor with the start winding reversed, it may start in the opposite direction. The main winding stays connected as normal.

As the circuit diagram tool isn't saving for me at the moment, let's see if ASCIIart will do.

         DPDT
    cap     ______________________|
-----||---/                       |
            ----|                 |
            ____|--start winding--|
----------/                       |
            ----------------------|

To identify if you do have all the wires for all the windings, measure the resistances between the wires with a meter. You are looking for two isolated windings. The main one will be lower resistance.

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The diagram below shows a likely internal motor circuit. There may be other possible internal circuit configurations. The green and red lines are the 115 V and 230 V connections. The start circuit is always connected in parallel to just one run winding, so it receives only 115 V regardless of the power connection.

If you can get access to the start-winding connections between points 5 and 6, you can swap the connections to the start coil to reverse the motor. That should only be done when the motor is stopped. I would not expect a good outcome if you attempt to reverse the motor while the shaft is turning.

enter image description here

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  • \$\begingroup\$ Thank You for the great info. I dug into the motor, it looks impractical to get to points 5 & 6. I think I will find a motor that states it can run CW/CCW \$\endgroup\$
    – steve
    Jun 23, 2019 at 15:15
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The simple answer is NO. This is a single phase AC motor. There is no polarity to switch to make the motor turn in reverse unlike a DC motor. The four wires most likely refer to Neutral, Ground, 110, 220.

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    \$\begingroup\$ Given that it's a 120/220V motor, yup, probably. There are single-phase induction motors that can be reversed (or at least that can be started in either direction) but they're specially made for that job. I wouldn't expect to find such a motor is an inexpensive drill press unless direction switching was a feature of the machine. \$\endgroup\$
    – TimWescott
    Jun 20, 2019 at 16:48
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    \$\begingroup\$ Well, technically ANY Capacitor start single phase AC induction motor CAN be reversed by changing the capacitor connections. But some motor mfrs do not provide you with access to those connections to make that change, so IN EFFECT you may not be able to accomplish it if that's the case. Often times the motor mfr will be nice and put that info on the nameplate, by stating something like 'Reversible" or "CW/CCW", but just because it doesn't say that does not mean it can't be done. That's why the calls for posting the connection diagram. \$\endgroup\$
    – JRaef
    Jun 20, 2019 at 21:21

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