How to Make a Cheap Motor Shaft Coupler for a WVO SVO SBC Waste Oil Gear Pump

Parts:

3/8" NPT pipe nipple (or any tubing with a 1/2" ID) about 2"-3" long. Under a buck from the home store.

1/8" Roll pin (AKA spring pin) 2" long. I got a package of 2 for about 2$ in the hardware drawers at the home store.

You will also need a 1/2" drill bit and 1/8" drill bit, a metal saw or grinder and a drill.

The idea is to use a section of pipe or tubing with a 1/2" inside diameter to connect the 1/2 shaft of the pump to the 1/2" shaft of the motor. The only thing I had on hand has a piece of 3/8 NPT pipe. The inside was a little too small, so I drilled it out with a 1/2" bit. It now slipped right over both shafts. If you already have, or purchase 1/2" I.D. tubing it will not need to be drilled.

Insert the motor shaft about 1" into the pipe and drill a 1/8" hole all the way through. Take your time, it's easy to break the tiny drill bit. Drive the roll pin into the hole until it is flush on the opposite side. Use your hacksaw or grinder to cut off the roll pin flush with the pipe. Keep the piece of left over roll pin, you will need it to finish the other side.

Now that the coupler is attached to the motor, it's time to attach the pump. I wanted to be able to remove my pump from the motor and drive it with my cordless drill if the motor dies, or I do not have 110volts available. Line up the pump shaft with the coupler and mark the coupler where the slot in the pump shaft starts. Drill through one side of the coupler with the 1/8" bit. Insert the pump into the coupler. The drill bit needs to slide into the slot on the pump shaft. Use the pump shaft to guide the drill bit as you drill through the other side of the coupler. Using the pump shaft to guide the bit ensures the hole for the roll pin will be centered. Drive the rest of the roll pin through the coupler and cut it flush. You should be able to insert the pump shaft into the couple and engage the slot on the shaft with the roll pin.

If you do not want to remove the pump from the motor, you can drill straight through the coupler and the shaft, just like you did the first side. The coupler can be removed from the motor by driving the roll pin out with a punch.

A section of quality 1/2" rubber hose will work in a pinch or for a temporary set up while experimenting. Use the hose that has the cord braided into it and secure it to the shafts with hose clamps. Keep the ends of the shafts as close as possible to help keep the hose from sheering.