Carbon Fiber Chassis Prep – Vintage Tech Tip

Advanced Carbon Fiber Chassis Preparation (Vintage Tech Tip)

Figure 1. Notice the square, sharp edges of the stock chassis. We are using a carpet knife V3 chassis for an example.

The chassis in your kit is very strong and ready for use right out of the box. However there is an easy way to provide extra protection for your chassis, it will
also actually feel nicer to the touch. The reason this tip can extend the life of your chassis is that rounded corners are much more resistant
to chipping, breaking and cracking than a square edge like the one on your stock chassis. In addition, the last step of this process involves
sealing the edges of the carbon fiber with Cyanoacrylate (CA) glue which further helps to prevent the separation (delamination) of the many layers
that make up your woven fibre chassis.

Click each image to enlarge

You will need the following:

1) A new chassis or your old un-modified      one completely disassembled.
2) A vice.
3) Medium Grit Emory Paper.
4) CA hobby glue fast or slow drying.
5) A well ventilated work area.
6) 600 Grit wet sandpaper
7) Warm soapy water.
8) Damp cloth to clean up any excess CA.
9) A face mask may also be a good idea
so that carbon dust doesn't get in your eyes, nose and mouth. Carbon is fairly inert but can cause some irritation to the skin and potentially the throat, lungs and eyes.
Just always be careful. 

Figure 2. Another  'before' shot of the knife chassis Notice the "grain" running the length of the chassis. Sand against the grain to remove  material and with the grain to finish with a smooth surface.

Figure 3. Sand across the grain just until the  edge is nicely rounded. 

1) If you have a vice use it.
2) Use soft Jaws in your vice (ie card board) to protect the chassis.
3) Use Medium grit Emery Paper cut into a 1 inch strip (8 ” long).
4) Place one side of the chassis into the vice so that one side of the chassis is pointing  upward on a slight angle as shown in figure 3.
5) Hold each end of the strip of emery paper and sand back and forth across the grain. Continue just until the edges are completely rounded. Try and remove only the amount of material required to achieve a nice round edge.
6) Do both sides and the front in this manner. Move the chassis around in the vice as you move to different parts and sides of the chassis.
7) Remove the chassis from the vice and now sand with the grain as shown infigure four. Sanding with the grain gives a smooth finish.
8) Place the chassis back in the vice front end first so the rear of the chassis is  extending upward As shown in figure 5.
9) Now sand again by pulling back and forth across the chassis, but this time do it very lightly… just enough
to slightly round the edges, this area of the chassis has the least amount of material and should be treated gently. This end of the chassis is also
less likely to take direct impact, so a completely rounded edge is not as important as the front and sides of the chassis.
10) Also sand inside all the holes back and forth lightly. Since there are a couple of  different holes in a couple of different orientations, move the chassis
around in the vice so each surface you are sanding is more or less parallel to the ground. This just makes the job easier. These inner holes are also not as easily damaged as the rest of the chassis so again, they do not need to be perfectly rounded like the sides and front do.


Figure 4. Sand with the grain up and down the length of the chassis to give a smooth finish

Figure 5. Be careful sanding the edge of  the chassis. You don't need to remove  a lot of material here

11) Now go around the whole chassis with a piece of used emery paper (so it is softer). Follow the grain all the way around the outside on the front and sides. Lightly sand the holes on the inside of the chassis as well.

12) Wash the chassis off with warm soapy water and a clean cloth

Sealing the chassis edge


Use thin CA as it is less viscous and will work best for the method we use to get the glue all the way around the edge of the chassis.

1)Holding the chassis up near eye level, drop a healthy bead of CA on the top corner of the chassis. Keep the chassis perpendicular to the ground
at all times. Let the bead of glue run slowly down the length of the chassis. Roll the chassis so that gravity can do its best to pull the glue along.
Add more glue just above the bead when needed (i.e. the glue is used up as it coats the edge of the chassis). Continue along until the entire
chassis edge is coated. Figure 6 shows the bead of glue after it has ran down one side of the chassis. At this point we rotated the chassis so
it would run down the front side. Try to rotate the chassis in a nice smooth gradual manner and try and keep the bead moving. If the bead runs
off onto the front or back of the chassis just wipe it off with a damp cloth as soon as it runs off. Try and keep the chassis perpendicular to
the ground and avoid any ‘run off’.

Figure 6. The CA should run around the edge  of the chassis. Don't hurry, but work with a bit of a sense of urgency. If it runs off onto the  front or back of the chassis just wipe it off with a damp rag

Figure 7. Hang the chassis to dry

2) After the glue as been applied all the way around, hang it to dry as shown in figure seven.

3) After it is dry, Wetsand with soapy water (dish soap) and 600 grit sandpaper lengthwise with the grain and polish to an ultrasmooth finish.

4) Inspect to see if you have sanded through anywhere… if so, apply a second coat of glue  and re-wetsand.

That’s it! A bit of work but well worth it.

Figure 8. A comparison of an unfinished piece  on the left and a finished one on the right.

Figure 9. Another  comparison of an unfinished  piece on the left and a finished one on the right.

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