PM66 Motor Replacement 3ph to 1ph
The Powermatic PM66 table saw was introduced in 1966. Boasting an all cast iron and steel table body with a one-piece, solid trunnion, this saw was heaviest in its class. This alone makes it the most sturdy saw on the market. In production from 1966-2008, it was eventually replaced by the PM2000.
It is common for these to need a power conversion from 3 phase to 1 phase, or vice versa. A power conversion usually involves replacing the motor and switch. This can seem complicated at first glance, but trust me, you don't need to be an electrician to do this conversion yourself.
We worked with www.mmtoolparts.com who is the largest distributor of Powermatic motors in the world, as such they get better prices they pass along to their customers. Below is a step-by-step guide on how to replace the motor and switch, including wiring instructions for the motor. All PM66 saws have the same motor configuration.
Step 1: Remove the old motor by pulling these two bolts that hold the motor mounting plate to the table. Remove the bottom bolt first, letting the motor hang from the top bolt. This will allow the motor to swing left so you can remove the belt, then pull the motor and mounting plate free from the top bolt.
Step 2: Measure distance between the pulley and mounting plate. You'll want to seat the pulley the same distance above the mounting plate on the new motor as it was on the old one to be sure the pulley stays in line with the others when reinstalled. Once you've taken this measurement you can remove the mounting plate and pulley from the old motor.
Step 3: Remove wiring and switch from the old motor and table.
Step 4: Use wiring diagrams to connect the new motor and switch. The first thing you'll notice if you're doing a power conversion is that 3 phase power operates with an extra, red wire. Single phase power requires only the black and white leads. You can use existing 3 phase wire by capping the red line at both ends, or get new 2 line wire at your local hardware store. If you're going from 1 phase to 3 phase it will be necessary to get a new 3 line with black, white and red leads.
Use two different wiring diagrams to see which wires go where, one for the switch and one for the motor. The motor wiring diagram is located on the motor itself, and tells you which wires will tie together. The switch diagram will be located in the user manual for the PM66. If you don't have a user manual, these can be found on our website at https://www.mmtoolparts.com/store/media/diagram/files/66.pdf. Find the correct switch wiring diagram for your motor, in my case I needed the Single Phase, 3 horsepower diagram. Follow the diagram to see which wires go where, and mount the new switch to the table.
Step 5: Install the mounting plate and pulley onto the new motor. This is where your measurement will come in handy, seat the pulley the same distance above the mounting plate as it was on the old motor.
Step 6: Mount the motor. Hang from the top bolt first, allowing the motor to swing left and reattach the belts.
Remove the slack from the belts and tighten the motor into place by securing the bottom bolt.
And that's it! You've just replaced a motor on a Powermatic table saw. For more detailed information please check out the video we made about this topic below. Leave a comment on the video if you have any questions, we'll be happy to find the answer!
Single Phase 3hp Switch:
Single Phase 3hp Motor:
Operating Instructions and Parts Manual (Wiring Diagrams):