I was recently in the Portland Japanese Garden where I saw a pleasant Shishi Odoshi fountain. It fills with water until it tips over and dumps the water out, making a noise that's meant to scare away deer that might otherwise eat your meticulously manicured garden. I was inspired to try to create a miniaturized, indoor-scale version, complete with pump and reservoir so it really works - right on your desk!
The basic theory of operation is simple: the main tube is weighted below the hinge and hollow above the hinge. Though the top is longer than the bottom, it still weighs less than the bottom when it's empty, so the tube sits upright. As the top of the tube fills with water, it eventually weighs more than the bottom, upsetting the balance and tipping over. The water spills out, the tube rights itself and the cycle begins again.
My design has a reservoir below the tube that holds about a cup (1/4 liter) of water and a small pump that cycles the water back up to the tube.
Here's a video of the fountain operating!
The main tube must be printed nearly solid (e.g. 70% infill). This is required because the bottom of the tube acts as a counterweight. If you print it with hollow or sparse infill, it may not work.
The remainder of the parts can be printed at a standard infill such as 20%.
You need 5 additional parts to assemble the fountain. They're all available from Amazon Prime.
Place the pump's mounting bracket over the pump.
Spread silicone sealant around the outside of the pump's inlet port - i.e., the part of the pump that will go through the hole in the side of the water reservoir. Putting the sealant on the port before putting the port into the reservoir makes for a better seal because it's hard to access all the little crevices after the pump is in place.
Push the pump into the reservoir. It'll take some force; I made it a tight fit on purpose to try and reduce leakage.
Place the M3x12mm screws through the outside of the base and through the pump mounting bracket. Tighten with M3 nuts. Ensure that there are M3 washers between the screw head and the plastic base, and between the nut and the pump bracket, as pictured.
Place more sealant around the pump's inlet port on the inside of the reservoir to keep water from leaking out the hole.
Cut a length of vinyl tubing to about 10 inches (25 cm). Push one end of the tube about 1.5 inches (3.5cm) inside the inlet hole so it's secure. (The inlet hole is on the same side of the base as the pump is mounted; see photos.).
Spread sealant around where the vinyl tube enters the inlet hole.
Place the square water riser tube in the top of the base (see photos) and spread sealant around the bottom of the riser where it enters the base.
Wait for the sealant to cure. The sealant's instructions will tell you how long to wait, probably between 24 and 72 hours.
Attach the other end of the vinyl water tube to the barbed outlet port on the pump.
Place the two support struts in the side hinge holes of the big tube and place the struts in the base.
Cut the end of the power adapter off and strip the wires and attach them to the pump. The pump's blue wire is positive and should be attached to the red wire of your power supply. The pump's brown is negative and should be attached to the black wire of your power supply.
- Fill the reservoir with water and plug in the pump!