1 Cut a large opening (about half the top) in the top of the steel drum.

2 Drill 11/2-inch hole in the bottom of the drum.

3 Weld the 1 1/2-diameter pipe in the hole at the bottom of the drum.

4 Attach the 1 1/2-inch brass ball valve to the pipe. This is the drain valve.

5 Drill a hole in the side of the drum at the bottom, same size as the heater element.

6 Fit the heater element making sure it is not touching the side of the drum.

7 Wire up the heater element.

Chemical Mixer Assembly

1 Attach one pulley to the rolled steel rod.

2 Attach the other pulley to the spindle of the electric motor.

3 Weld the propeller to the other end of the rolled steel rod (shelf brackets).

4 Attach the rod, pulley and propeller assembly to one side of the hinge.

5 Weld a piece of angle iron across the top of the drum.

6 Weld the unattached side of the hinge to the angle iron so the propeller and rod assembly sits in the middle of the drum. The hinge should swing the propeller and rod back and forth.

7 Mount the electric motor on the side of the drum.

8 Fit the belt to the pulleys and tighten by wedging a block of wood into the hinge. You also need to fashion a simple wooden measuring stick with 10 litre increments.

Other information: A hydrometer is a good piece of kit to have to measure the specific gravity of the biodiesel. The specific gravity of biodiesel should be between 0.860 and 0.900, usually 0.880. The specific gravity of vegetable oil is 0.920 therefore the specific gravity of biodiesel should be lower than the vegetable oil used to make the biodiesel.