By Philippe Gohier

Page1 - Male Mold    Page 2 - Female Mold      Page 3 - Building the bike

This Space Age carbon fiber monocoque fwd 20x20 lowracer was designed by Philippe Gohier of Montreal, Quebec. He used the 3D program from to design the bike. 
The scale of these renderings can be determined by the 4 x 4 inch grid in the background.

The design was created with aesthetics in mind more than aerodynamics, but it should still be pretty fast!

Click on the images for a higher resolution view.

Phil says the plans took him over a year to complete. He started construction in the middle of January 2005, and hopes to finish in April.

He verified that all the clearances were ok within the Blender program. It even simulates the wheels rotating.  The seat is 7.5" from the ground at the  lowest point from the ground and the center of the crank is 15.5" from the ground.


Another cool thing about Blender is that it generates the layers to build up the mold from sheets of medium density fiber-board (MDF).

This picture shows the CAD view using 1/4 in mdf sheets cut in correct shape from the 3d program.

Yes, it's a tiny bike, like every 20x20. It's calculated to fit a person between  5' 4" and 6' 4".  

The layers from the Blender program were printed at 1X and then traced onto the MDF. The MDF sheets are then stacked and glued.
The layers of MDF are ground smooth until the outside matches the inside of the next panel.

Automobile body putty (green stuff) is added to fill the holes. An orbital grinder is used to smooth it out.

Wow, That's going to be a small bike! It will fit fine though. 

Phillip says he will use a  normal mountain bike hub (with disk brake) and a Shimano 105 12-25  derailleur.

The plug come in 3 (for now) parts for de-molding consideration. This will allow the bike to be laid up in 3 different sections, and then bonded together.

Phil is now working on bondo-ing and sanding the molds, which is a very tedious and time consuming process.

With blender you can do "compositing", which is a process that allows you to to mix real pictures (or movies) with 3d simulations.
The 4th part (the back) is glued into position, then the other 3 parts are glued together. I had to reposition it to it's correct location place and then reshape it. 

The strips of wood are there to tack it together while the glue sets. 

Here's the back end after the holes are filled with bondo.

Yes, the dates on the pictures are wrong...

The bondo is ground down to a rough finish
Center lines are marked on the mold to allow it to be finished symmetrically.
Here's the plug with a gap between the seat and frame.
And after it has been filled in with bondo and sanded.

NOTE: there is de-molding wax (4 coats!) between the separate parts, to allow them to be separated later. 

How do you keep all those sexy curves symmetric?

hmmmm.. almost... 

The trick is to verify that that it's symmetrical everywhere. 

Now it's back to grinding and sanding with the orbital sander (paper:180), and filling bondo holes. 

That's it for now. 2 weeks for that! Next update: finishing symmetrical correction (no more than 1/16 in of error at this point), separating the parts, shooting a gelcoat, sanding, polishing 

When the mold was ready, I shot it with white gelcoat to make a smooth finish. I used 5% gelcoat, an air dry , and then some acetone. This wasn't too good, I should have used the gravity gun, not the pop-corn gun. 
Now it's time to make the false flanges for the molds. This series of pictures shows the principle for molding a multipart female mold.

A flange is needed to separate parts. The dark grey object is the mold. In this image, the false flanges (blue) are placed in their correct location. 
Next, orange gelcoat is shot onto the mold and flanges. 
Then, fiberglass is laminated over the mold and flanges. 
The first false flange is removed, and the orange gelcoat is shot on another side of the parts.
Until each side of the female mold is complete. 
To make the false flange, I laminated a flat panel of 1.5 oz fiberglass with a lot of FLEX to make it flexible. 
I then screwed the fiberglass sheet to a template with the same curve as the mold. 

Then I placed the mold on the fiberglass and cut it to the correct shape. 

Now i can re-glue the parts together to make it perfect.

When the model has no more waves, it is symmetric and has been sanded everywhere at with 80 grit sandpaper, it's time to screw an MDF panel to the end of the boom for vacuum bagging convenience.
Now it's time to shoot Duratec primer, which is a sort of gelcoat.  

On the Orion Speedtrike page, I see black gloss on the mold, maybe its the same...

Pot gun: head number 5. 
Air pressure from compressor: 70-80 lbs

Catalyst 90 at 2%  gives you a five minute gel time, meaning you have five minutes to shoot, or you scrap the gun! If you add less catalyst, it will not cure.

The first step is to shoot 80 mils of inch (which is very thick)

So, days later, I have sanded it using 80 grit then 120 grit. Be sure to sand it in a regular motion, not spot by spot to be sure it's smooth. 
I used a regular paint gun (you can use gravity feed or suction) to shoot a thin coat (10 mils) of duratec primer on the mold.

The right way to do it is to wait 2 full weeks after shooting the primer to wet sand (400-600 grit) and polish. Vapors in the duratec will go out and it will get it's max toughness. In a shop where you need to get the production quickly, you can sand it 2-3 days after applying the primer, but the quality of the surface can be affected. 

So, there is the finished model sanded with 400 to 600 grit wet paper, then polished with TR coarse compound, TR fine compound and TR glaze sealer 

Now you need to cover the plug with a de-molding treatment. This involves 2 layers of frekote mold sealer and 3 layers of frekote wolo (mold release agent).
Go to page 2 - Making the female molds  

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