Step 1: Tools and materials you'll need:
- 1 Rule 1100 GPH 12VDC Bilge pump.
I used these because I could get them, other sizes or manufacturers might do fine too.
- 1 RC model boat propeller for example Graupner No. 455/10.
This is a 2-wing 70mm diameter prop with 4mm threading. Don't use to big propellers.
4-blade are also ok, but use a smaller one.
- 1 Coupling bush for smaller than 4mm diameter shaft. Graupner No. 3346 (3.2mm) is ideal.
- a 20mm long 4mm bolt with the head removed.
- a 4mm spring washer.
- Heat shrink tube of different sizes with glue or (better)a waterproof cable repair set like Raychem XBL22 (also, this is what I could get overhere).
- round circumference 2 conductor wire capable of carying 4A.
- adhesive rubber pads, like the stuff to put under furniture.
- waterproof cable gland (for example Velleman CPG135)
- Hacksaw or dremel
- sharp knife
- electric paint stripper
- threading tool with 4mm bit.
- soldering iron
- pliers, screwdrivers etc...
Step 2: Prepare the bilge pump:
Remove the lower blue part (klicks off). Remove the little propeller so the metal axis is free.
Take the hacksaw or dremel and cut around the white plastic,about a mm or so from the red area (don't cut in the red plastic).
Remove burrs with a sharp knife. You'll end up with a watertight motor in a nice red housing.
The black stuff in the picture is some adhesive rubber, which comes in handy to distribute the force once the motor is mounted on the robot (see further).