A New Bottle Topper Design October 20 2014, 0 Comments

The old design

On a recent camping trip, we took Bartendro out to make drinks for our friends in the fine outdoors. Each bottle had a single tube draped down into its liquid with no bottle topper to keep the bugs out. A small swarm of bees got wind of the sweet scent and in no time, regular sized bees were negotiating themselves down the crowded bottle neck. Unfortunately, the exit seemed to be much more elusive than the entrance, and they found themselves drinking and swimming in what must be the most decadent way for a bee to go. Unfortunately, the camp-goers weren't quite as happy as the bees. After a few hours the bees were bobbing in the sweet stuff. Off-putting, I know, but this was inspiration to refine a component of Bartendro that needed some attention.

Before Bartendro made its debut, the first comments that people made were about the exposure of booze to the open air. We understood the concern. Even with the tubing hanging down into the bottle, there was still plenty of space for fruit flies (even bees) to find their way to the delightful nectar. Commercial environments, especially bars and restaurants take this very seriously and every night the bottles are capped with plastic wrap or some other type of closure. It's a real sanitation concern and we made sure that we would address it before shipping any of our Kickstarter orders.

Our solution was these plastic bottle toppers that could allow the input tube and level sensor tube to pass through the bottle top and not allow any fruit flies in. 

While effective, there were a couple of problems with this design. Sometimes, when catering a small get-together or out of sheer laziness, using the liquid sensor tubing wouldn't be desirable. We often run the bot without the second tube because we're usually standing next to the bot and monitoring it anyway, and we don't want to clean a second tube for every bottle at the end of an event. If we were to use the bottle toppers, we would still be left with a gaping hole for pests to get into. The second problem was more of a logistical and manufacturing one. These parts were quite difficult to source, expensive, and slow to modify.

We needed a better way to close up the bottles whether using one or two tubes. After much experimentation, here's what we came up with:

We found that it was nearly impossible to make a one-size-fits-all type of solution. There was simply too large of a range to make an elegant solution. We created a large spreadsheet and measured as many bottle openings as we could get our hands on. The data showed us that there were four distinct groupings of opening sizes so we decided to design for those. This covered everything from a narrow dessert wine to a wide-mouth cranberry juice bottle. There was a limitation in that some bottles could not accept two tubes to begin with, so we did not design for bottles that were that narrow.

The plugs are slit in a similar way as fountain drink covers, but instead of poking a straw through, you poke your tubing through. We tried many variations of slit length, number of slits and distance between both slit patterns before we reached the optimal design. The hole in the center is the biggest opening at 0.010" and about 0.002" when a tube is inserted. The average fruit fly body is about 0.030". The part is made of food-grade silicone, it is soft and flexible, and will allow the passage of the tubes in either direction hundreds of times without tearing. 

We will now be including these new caps with all new bot purchases. In the near term we will likely make them available for purchase individually, and they should range from $3-$5 depending on size.