The Bicycle Bubble Machine

Summary

Full video: http://youtu.be/-RRaYNLv_Zs

Finally, be the star of commuter traffic! Make all the kids in the neighbourhood happy! Or just jealous! Engage in inspiring discussions with chemtrail believers! With the wind-driven Bicycle Bubble Machine drawing a dense stream of soap bubbles behind you, you too can bring peace and happiness back to the streets! 

The Bicycle Bubble Machine is a bubble machine attached to the luggage rack of your bike. I actually found bicycle-mounted bubble machines on the net, but they all run on batteries, neglecting the fact that on our bikes we have a source of energy which is much more sustainable and fun: relative wind. 

The Bicycle Bubble Machine only uses the relative wind created by riding your bicycle: a wind wheel will turn a wheel with bubble wands, which are blown directly by the relative wind. It works surprisingly well at a comfortable range of speeds, and with the funny, jet-engine look the machines have, when one is attached to every side of your bike, it's an eyecatcher. Well, at least it gave me a lot of strange looks when using it on the street. 

This is my first real project constructing something which moves. While I'm not an engineer (so please be kind!) I did put a lot of work in this (and printed lots of prototypes ...): for example the tank was supposed to be printable in one piece, store enough liquid, not store too much liquid in 'dead' places, and not spill all the time while cycling. The design now for example has bulkhead walls to reduce sloshing effects. That said: it will still get messy, but that's part of the fun :) 

While I thought about a gear system, I discarded this idea, because everything I could come up with led to a) a smaller tank, b) larger dead spaces of fluid, c) too many wind turbulences in the bubble path etc. 

Future improvements might be: a lever to temporarily block the bubble wheel, so you can turn off the machine when it is not needed; and modifications to the bubble wheel like combining two bubble rings to a long one for larger bubbles, or improving the topography of the bubble rings to store more fluid. 

For the pulleys, I used Parametric Pulley by droftarts. I kept them although I dropped using tooth belts (replacing it with elastic ribbon), because they give good friction.

Print Settings

Rafts: Yes

Supports: Yes

Notes: For the tank support "from printbed" not "from everywhere"!

Instructions

Don't be scared by the long instructions. It's easy, I just want to be precise. If there are questions, please ask in the comments. If you want detailed instructions with pictures, please see my instructable on http://www.instructables.com/id/The-Bicycle-Bubbl...

Apart from printed parts, you will need:

- a piece of wood to mount the machine on, which will then be put onto your luggage rack; I used 10cm x 70cm to have one bubble machine on each side (the wind wheel mount protruding a little over the edge of the wood); you should take less than 10cm width, however, as some bubbles that move down are less likely to pop then small self-tapping screws (so your plastic doesn't break), optionally also small wood screws sewing accessories: 

- elastic ribbon (the stuff that makes your knickers hold, I used 8mm wide black), needle and thread, fixing pins something to make the axles for the two wheels: I used 2mm welding wire (straight sticks); toothpicks will work, too, but they will break easily small drills (like 2.5mm) to drill open the holes for the axis, as many 3D printers will not make the holes dimensionally correct; screwdriver and the like

Print one of every part, two of each clip (measure the diameter of the tubes your luggage rack is made of and tell me, if you need different clips). Print either two 3mm spacers or one 6mm. 

As for the slicer settings:

it is very likely that you'll need a raft to print at least the wind wheel; on my (probably badly calibrated) printer I also needed a raft to print the tank the tank should be as solid as possible so it doesn't leak bubble fluid. My first tank with 20 % infill, two perimeters and two top/bottom layers leaked -- it didn't render it unusable, but it got soapy on the outside and if you left the tank full at evening, there wasn't much fluid left the next morning. I then did three perimeters and four top/bottom layers, which made it better. You might also consider a coating for the tank you should enable support from printbed only, not elsewhere! This is because, inside the tank, there are bulkhead walls to prevent sloshing effects, which act as support also, but having additional support inside the tank will make it store less fluid, keep fluid in dead places and will be a mess to remove; but you will need support for the mount, so enable from printbed the tank will need a lot of bridging (roughly 10mm) in the slanted that begins at a Z-height of about 40mm; give this good layer cooling while I use the clips in PLA right now, I will replace them by ABS ones, which will last longer.