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Soap bubbles generator

April 30th, 2018 Leave a comment Go to comments

A simple machine for making and blowing soap bubbles.


Completion date: 20/04/2018
Power: electric (Power Functions)
Dimensions: length 38 studs / width 14 studs / height 18 studs
Weight: 0.419 kg
Motors: 1 x PF M, 1 x 2838

I’ve had idea for a LEGO machine that blows soap bubbles for quite a while, and I felt compelled to finally build it after I’ve learned that there are real-life machines for blowing bubbles. It was dead simple, but went through a number of iterations.

The machine was built on top of a LEGO boat hull, which was used in a somewhat reversed fashion, that is for holding fluid inside rather than floating in a fluid. There was a LEGO track acting as a conveyor belt, motorized with a PF M motor and pulling a number of empty LEGO 3×3 wedge belt tires in and out of the fluid. Once out of the fluid, the tires would pass in front of a fan driven by a 2838 motor. The whole thing proved reasonably efficient at generating bubbles.

Despite its simplicity, it was just one out of several variants I’ve experimented with. My initial idea was to build the whole thing on top of a large LEGO mug, with a single tire being pulled in and held up to the fan in a manner similar to how a person would blow bubbles. Then I realized this would result in only a few bubbles being blown per minute, so I went for efficiency, which called for a conveyor belt. It was also my ambition to use a single motor to drive both the belt and the fan, but in the end this proved impractical, as the rotational speed between these two differs over 90 times. I’ve also ran some test with the conveyor belt being stopped every time a tire is in front of the fan, and with ducted fan for blowing air precisely into a single tire. This, however, did not prove any noticeable increase in the number of bubbles being blown, and I saw no need to make things more complicated without any real advantage.

In the end, it was a fun exercise in simple mechanics, and a pleasant way to spend a sunny afternoon.


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