Replacing a Wood Lathe Motor With a Treadmill Motor

Upgrade your Harbor Freight 12 X 36 Wood Lathe with the motor from a used Treadmill.

Step 1: My Lathe Motor Goes Out in a Blaze of Gory. (No, I Didn't Misspell It.)

I have a Harbor Freight 12 X 36 Wood Lathe. I was working on turning an Oak bowl when the motor shorted out.
"Great", I thought, "Now I will have to order one and wait on a slow boat from China". (This motor was supposedly rated at 3/4 horsepower, but those in the know say it's really more like 1/3 horsepower).
I remembered that I've seen videos of how other people have used Treadmill Motors on other power equipment, so why not try to put one on the lathe?

Step 2: Finding a Used, Cheap, (Preferably FREE) Treadmill.

Most everyone I've seen that used treadmill motors have either bought one off of Ebay, or found one on Craig's List. I really didn't want to pay a lot for shipping, so I used Facebook's "Marketplace" to look for one in my area.

I couldn't believe my luck! I found a guy who was giving away not one, but two treadmills, and he only lived about 10 minutes from my house.
High-Ho Pickup Truck, Away!

Step 3: Tearing Them Apart to Get at the Good Stuff.

When I got them home I started taking them apart. I took the electronics, wiring, and, of course, the motors. One motor was rated at 2.0 horsepower, and the other at 1.8 horsepower.
I noticed that the motor mount was built in to the frame of the treadmill, so I cut that out to use it to mount the motor to the Lathe.

Step 4: Let the Modifications Begin!

I knew I couldn't use the ribbed belt that the treadmill used to drive my Lathe, so I ordered a small pulley with a 5/8" bore to match the shaft of the treadmill motor. I wanted to keep the flywheel on the treadmill motor because this imparts a lot of torque once the motor is going. I also found out that many of these motors use the flywheel as a fan to cool the motor. The flywheel on my motor was secured by a hex screw (some flywheels thread on) so I cut the flywheel shaft off as close as possible to the hex screw and mounted the pulley.

Step 5: DC Not AC

Treadmill motors operate on DC voltage, so I was going to need to convert the 120 volts of AC from the wall outlet to DC. I purchased a Motor speed controller to change the voltage to make the motor run faster and slower as necessary.
"But", I hear you say, "I thought you said it had to be DC voltage?" Well, you're right. I also bought a bridge rectifier to change the AC from the motor controller to DC. It fit very nicely on the motor controller.

Step 6: Control Box

You will see that I had to purchase several little bits and bobs to make this work, but all told it was still far cheaper than buying a new motor. I already had a metal box laying around the shop so I decided to put it use.

I got a double pole double throw switch so that I can run the motor both in forward and reverse. The picture shows how to do the wiring. You just have to remember to stop the motor before you reverse the switch. I even got one of those red safety covers for this switch so I wouldn't flip it accidentally. Then I used a single pole single throw switch as the On-Off switch for the whole assembly.
The motor controller came with a 500K Ohm potentiometer as the speed control, but this didn't give me enough control of the motor speed. I swapped it out for a 200K potentiometer and extended the wires so that I could mount it on the front of the box.

Step 7: Modifying the Reeves Drive

Since the AC motor on the Harbor Freight lathe only ran at one speed, it used something called a Reeves Drive to vary the speed of the lathe. This drive consists of two split pulleys. Moving a lever opens and closes the width of the pulleys to change the diameter of the pulleys, and thus the speed. Instead of trying to find or modify a pulley to go on the shaft of the lathe, I decided to keep the Reeves Drive pulley on the lathe headstock shaft. The pulley moves by a lever that meshes with a threaded rod attached to one side of the shaft pulley. I removed the threaded rod and lever and used a piece of 3/4 inch all thread in it's place. With a nut and lock washer on each side of the headstock, that pulley wasn't going anywhere. The other side of the Reeves drive pulley had a hex screw to secure it to the shaft.

Step 8: Almost There...

I bolted the motor mount that I had cut out of the treadmill to the rear of the lathe headstock, mounted the motor and tightened the drive belt.
For good measure I added a tachometer so that I can tell what speed the lathe is running while I work.