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Old 07-19-2011, 10:07 PM   #18
Sir Not Appearing
That's no ordinary rabbit
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Joined: Jan 2008
Location: Indiana: Motorcycle Hell
Oddometer: 1,114
Can be applied to motorcycling...

At the beginning of last school year, I had just been called back in late July and moved to the high school with little time to redo the curriculum. One of my assigned classes was a thinly disguised 1950's Metals class that they were calling "Manufacturing". I was met with blank stares on the first day when I showed the students the projects the teacher had done the year before. I had to think quick and come up with something and nothing works with high school boys like speed and competition.....

I started thinking and remembered that I wanted to learn how to work with fiberglass myself, so I decided that I would introduce composites and plastics into the "Manufacturing" class. I decided we would be building fiberglass-bodied, rocket powered cars with ABS-plastic chassis that would be raced on a 300ft track outside. After I built a prototype and test fired it a few times, the kids were instantly pumped about the project.

Since we were working with limited time, limited budget and each student was only making one project, I decided to use the lost foam method. I had seen some posts on R/C forums (another hobby of mine) where guys made boat hulls and airplane fuselages using this method.

A very quick version of how we did it:

  • Cut, glued and sanded insulation foam (pink or blue, doesn't matter) into shape.
  • Covered the foam (except the bottom) with a layer of cheap packaging tape to protect the foam from the resin
  • Laid 3 layers of fiberglass
  • When cured, turned them over and poured acetone into the bottom
  • Pour the foam goop out and prep the bodies for finishing
Here is one of the better ones. Since his pickup had the aerodynamics of a brick, he left the wheel wells closed to help out a little. IIRC, the accelerometer showed that this one was in the 40mph range, however we had some in the 60mph range.

The Batmobile-esque car in the foreground took lots and lots of time carving, sanding, shaping, etc. and I wish I had a better pic:

Sure, its not motorcycles but the lost foam technique can be used for pretty much any application where you only want to make one example of the part. I'm going to use it to make some Buell 1125CR-esque pods to hide some of the guts of my naked Ninja 500 that were originally covered by the fairing.

Here is a short but informative article about lost foam technique at
1998 Triumph Daytona
1991 EX500
2007 Suzuki S50

Sir Not Appearing screwed with this post 07-19-2011 at 10:13 PM
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