Introduction: Portable Bench Grinder Using Old Furnace Motor
Have you ever had to work away from your shop, but still need a grinder. I have, so here is the solution I came up with. I had an old furnace motor and an arbor. Very handy to have and simple to make.
1 - Piece of 3/4" plywood, cut to your dimensions
1 - Arbor (available at most hardware or tool stores)
1 - Pulley
1 - Fan belt
1 - Extension Cord
1- Electrical Box with switch and switch plate
2 - Grinding wheels
Some mounting hardware (screws or nuts and bolts)
Cut the piece of 3/4" plywood to your dimensions (mine is 13" X 22"). You can leave it raw or paint it. Now layout where you want to mount the furnace motor and arbor and mark the mounting holes. The position of the motor and arbor will depend on the length of the fan belt you choose. To mount these two items I would recommend sturdy wood screws or T-nuts and bolts.
Mount your pulley on the shaft of the furnace motor making sure it is the same width as the pulley that is on the arbor. The pulley on the arbor is in the centre of the arbor, which means you will have to take the shaft off of the arbor to get the fan belt on the pulley. Make sure when mounting your motor and arbor with the fan belt attached that there is sufficient tension on the fan belt. It doesn't have to be real tight, but tight enough to keep spinning when pressure is applied..
With the motor and arbor attached to the plywood it is time to wire the motor. Take the extension cord and remove the female end. You can wire this directly to the motor so when you plug it in the grinder starts up. I choose to add an on/off switch. I took a closed electrical box and ran the wires from motor to the electrical box. I then took the extension cord and ran it to the electrical box and installed a regular light switch and switch plate. Put on your grinding wheels, in my case a grinding wheel and a wire wheel.
Make sure everything is firmly attached, flick the switch and grind away. There is a lot of vibration so it is best to clamp the plywood to a workmate or saw horses. Now as long as there is electricity, you can grind anywhere. I have found it to be extremely handy.