Instructables

Soul Cycle Mothership, a molded fiberglass speaker cabinet for bicycles.

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Picture of Soul Cycle Mothership, a molded fiberglass speaker cabinet for bicycles.
After creating 5 or so fully custom Soul Cycles, painstakingly, one at a time, I needed a way to create attractive cabinets in a fraction of the time. So I invested extra time in the process of making a mold to be able to reproduce an attractive curved form in fiberglass. Now Rock the Bike can bust out a Soul Cycle Mothership in about a week, not months like the previous custom bikes.
 
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Step 1: Sketch shape you wish to mold, keeping in mind undercuts in molding process

Picture of Sketch shape you wish to mold, keeping in mind undercuts in molding process
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An example of an easy shape to mold would be a beach ball. An example of a hard shape to mold to would be a stegosaurus. What makes the stegosaurus harder? It has features like legs, that will make a left / right mold unable to pull apart. The spikes on a stegasaurus' back would create steep draft angles that would make a top/bottom mold difficult but possible to release cleanly.

For my bicycle music system, I chose a shape that was relatively easy to mold with a left / right mold.

Step 2: Create a rough version of the shape, in foam.

Picture of Create a rough version of the shape, in foam.
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In order to create your foam shape, you'll either have to sculpt it freeform like Michelangelo, or carve it from a block of foam with CNC tools, or use routers and templates to help you make it. I chose to use templates and routers.

In the series of photos you see that I stacked the templates (which are made by 'tracing' a master template with a router) with threaded rod. Then I shot expanding foam into the form (inside a garbage bag.)

Then I used a hot knife to slice away the excess foam. The masonite templates stop the knife from cutting too far.

Step 3: Hot wire, carve, and shave your foam block down to a curved form.

Picture of Hot wire, carve, and shave your foam block down to a curved form.
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I first tried a Shurform tool (basically a cheese grater) to remove material, but the hot wire was much more effective.

Step 4: Smear nooks and crannies with some kind of resin or filler that is sandable.

Picture of Smear nooks and crannies with some kind of resin or filler that is sandable.
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Foam has big holes that need to be filled. Thicken epoxy resin with Microballoons and smear that stuff all over your form. I recommend using a different dye for each layer that you build up, so when you're sanding later you'll know when you're about to hit foam.
kbaltrip8 months ago
what's up paul? it's in from SCRAPERBIKEs
Duke Luke4 years ago
What kind of foam do you use? And where can I get it (as well as these other materials)?
abadfart4 years ago
very nice but id mount it like the tank off of a motorcycle   
supe woow man amazing
how did you get the right shape for the inner panels?
trebuchet035 years ago
Hey FossilFool! I was in SF this past summer and saw your Choprical Fish ride at the bike music festival (I've seen it in photos before, but seeing it in action is a different story)... It was inspiring enough for me to make a bike sound system using a megaphone amplifier and boombox speaker.... But that wasn't enough for me. It was nice for riding, but far from a the party bike I so wanted to recreate. It's unfinished as of yet - I need to upholster it, make a longer kickstand, add lighting (built into upholstery), etc... Thanks for the inspiration! The instructable will be ready shortly after the project is done :D
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hey... cool ride there "catapault" i wish i had a sun EZ so i could build a recumbent party bike. then you can cruise all day comfortably. unfortunately, where i am, fools that have sun EZs want list price for them 2+ years old! huh? nice job on the fabrication too. as you don't have an actual webpage to link to, you mind if i post your pic on my street party bike site?
BobicusIX5 years ago
Awwww..... I thought it looked like it was gonna be like gel to the touch..... i was really disappointed when you didn't use gel and such
cacaloz5 years ago
if falling rain??? but it very good.
what kind of amp is in there?
nagutron5 years ago
This is amazing! The lighting effects are great. We really could have used one of these at 19th and Valencia on Tuesday night when everyone was out dancing in the street after the election :)
dark sponge5 years ago
Awesome! You should enter it into the light up your ride contest!
John Smith5 years ago
thats one badass amoeba. ha, this is actually very cool, i love it. +1
Sandisk1duo5 years ago
you might want to seat the speaker box, you will get much better, lower bass

also consider filling it with acousta-stuf

great instructable!

How many Amp Hours is your battery?