Originally, I was going to build the floor pan out of aluminum.  In fact, I was actually quite excited to do so and thought I would either buy or build a sheet metal brake so I could bend the edges.   But for some inexplicable reason, I felt compelled to build it out of composite instead.  It would have a few advantages, namely:

1. Lighter weight, although not enough savings to justify it on this reason alone.
2. Less rattling
3. Provide greater strength
4. Facilitate built-in supports for pedals as well as  raceways for cables & tubes
5. Integrate a foot rest for the left foot
6. Enable me to simulate fake radiator/transmission if I decided to go that far
7. Minimize the adjustment for the front suspension spring

I decided to go with fiberglass simply because I had more of that material laying around than carbon fiber.

I also contemplated at length how to build the “tub.”  I could either go moldless by building the bottom piece then adding on the sides, or build a mold out of wood.  After much thought, I decided to build a mold.  This would allow me to do the entire tub in one layup rather than many which could end up taking upwards of a week. 

I began by marking cardboard pieces to get the shape of the bottom and sides.  I then transferred those to the wood.  After cutting out the pieces OSB, I used my air nail gun to assemble the pieces together.  I think it came out real nice.  I next lined the interior of the mold with aluminum foil so the epoxy and fiberglass do not stick to it so it so the part can easily be removed.  The foil does not stick to the epoxy so the part will come out easily. 

The foil approach did not go as smoothly as I had hoped.  It was very thin and broke through in several places that required patches before I even began my layups.  As this was going to be a more difficult layup, I did not want to be fighting loose foil, so I ripped it all off and painted it with a very good white primer to seal the wood.  The finish of the OSB was still too rough so I applied a thin coat of joint compound then sanded and painted it once more.  I also bought some mold wax relief that I will use to keep the fiberglass part from sticking.  It will take three or four coats.  I’ve never tried this approach before so it’s yet another learning opportunity, or at least that’s what I keep telling myself as I get deeper and deeper into this fiberglass approach.

After watching some more YouTube videos, I believe I need to coat the inside of the mold with gelcoat to give it a smoother finish.  You can buy gelcoat with and without wax mixed in.  The wax gelcoat mix is less costly so that’s what I went with.  Once I got it, I mixed it per the recommended ratio and quickly applied it.  The I placed the entire mold in my composit oven and it set up nicely.  But boy did it stink up the garage.  The stink filtered into the house a little which did not make my wife happy.  Even after leaving the garage doors open for extended periods, the smell lingered on for several weeks.  I am not likely to use this again unless I do all the work outside.

I plan on a composite structure using 3 plies of uni, then 1/4″ Divinicell high density foam, followed by another 3 layers of glass.  The glass fibers will be oriented at 60 degrees left of the center for the first layer, then 60 degrees to the right for the second layer, and finally one layer straight down the middle. 

Once the first three layers of fiberglass are down I will use a thin micro-balloon slurry on the front and back of 1/4″  Divinycell foam to provide adhesion to the fiberglass without robbing the glass of its epoxy before laying it down on the first three layers of glass.  Then I will lay in three more layers using the same schedule as before.  I believe this will give me more than adequate strength.  I might add two more layers on the floor pan under my but and where I will step in and out of the cyclekart.  The layup will all be done on the inside of the mold. 

I will do this all in one layup session and then place it in a custom-insulated/heated curing box I have built, see My Composite Curing Box.  The insulated heater box will enable the part to cure within 24 hours even though the garage temps might be down in the 30-degree range.  I tried a carbon fiber layup early in the spring and it was still soft after one full week due to the cold garage temperature, so I don’t want that happening again.

Dec 24

Winter has hot really hard with very cold temps and lots of snow.  It was 11 degrees below zero at 10:00 AM with the sun shining brightly out side just a few days ago.  Getting my garage up to temp under these conditions can take 2-3 hours if not more, so I have held off fiber-glassing anything right now.   Hopefully, more moderate temps will return so I can get the floor pan done and installed.