The seed for this project was the desire to mechanically measure specific amounts of liquid in a way that was both adjustable and easy to clean. In the past, I have used measured pour spouts on cocktail machines, and they work fine, but they are not adjustable and occasionally they just stop working.
I started by thinking about the Japanese Shishi-Odoshi ("deer scarer") bamboo fountain feature, which measures liquid against a counterweight and pours when the liquid reaches a certain level. The system is wonderfully simple, with one big caveat: the liquid never stops pouring.
So I began prototyping on a piece of plywood with a plastic cup. I new that the receptacle had to be lightweight, so that the liquid would make up the majority of the total weight and be easier to fine tune the "cut off" point for the pouring. I discovered that the pouring mechanism would actually need four parts:
- The bottle of liquid above with a flanged pin valve, which releases liquid when pushed up. I made a stainless pin and used a little piece of silicone sheet as a gasket.
- A receptacle below. The receptacle needs a hook to latch onto the counterweight arm. I made a little four-bar set so that the cup would pour where I wanted it.
- A counterweight arm with a little ledge that the locking arm can lock onto
- A lock arm that pushes the bottle's pin valve up when activated, and locks onto the counterweight arm.
When the cup is lifted, it pushes the Lock Arm up, releasing liquid. As the Lock Arm lifts, the Counterweight Arm lifts also and the two lock together. The hook from the Counterweight Arm is now holding the cup up. When the cup fills with enough liquid to overpower the Counterweight Arm, it pulls free of the hook and pours, while the Counterweight Arm pulls free of the Lock Arm and the bottle is sealed again.
It pretty much works. A little leaky, but overall a great first step.