I spent the last few days repairing the chisel marks, rubbing down and polishing the tank base mould, not because I want a pretty underside to my tank but because I want to ensure the CF separates from the mould. Unfortunately, all that rubbing down (240/600/800/1000/2000/4000 wet and dry) has given me a Repetitive Strain Injury (RSI), all the tendons on the back of my right hand have swollen and it bloody hurts to move my fingers, the only cure is not to use the hand for a couple of weeks. I am also definitely not ambidextrous – rather the opposite. Here it is repaired and coated in release agent:
I need some CF sheet to make a) a panel to go under the seat hump, b) a dashboard panel for inside the fly-screen and c) some baffles to go inside the tank top to limit the fuel sloshing around. This afternoon I cleaned up a sheet of window glass, applied release agent then laid down some epoxy compatible polyester gel coat. It is very tricky to apply the gel coat, thick enough to ensure coverage of the glass but not so thick that the surface is lumpy, I erred on the lumpy side simply because I mixed too much gel coat.
Before mixing up the epoxy resin I broke out the carbon fibre woven mat to cut it to size. It is a swine to work with as the weave is very flimsy and it is incredibly easy to catch a strand inadvertently and ruin the cosmetic look of the mat (first with an errant piece of selotape used to seal the polythene sheet it came wrapped in and second with the point of the scissors as I was trying to cut it). As a mat, it has no mechanical strength and cutting a straight line is quite difficult as the weave distorts with the pressure of the scissors and your required square piece becomes trapezoidal.
The epoxy resin has the consistency of cold golden syrup and the hardener which is mixed 100:30 is like 10W oil. When you add the hardener it just floats on the surface of the resin. Using a lolly stick I gently mixed the two components but after about 3 minutes I noticed that the mixture was full of air bubbles. I had to wait about half an hour for the bubbles to rise to the surface all the while hoping the resin would not start to go off. Applying the resin with the bubbles included would have compromised the strength of the finished sheet. Mixing catalyst and resin requires patience and very, very gentle agitation.
I used 2 laminations of CF mat and probably mixed about 5 to10% too little epoxy resin and was really pressing on the roller to get the resin to force through into the second lamination.
I learned a lot today and am very glad I chose the manufacture of sheet as my first CF component attempt. I suspect the cosmetic look of this piece will mean that it will be relegated to inside tank baffles, we shall see tomorrow when I separate it from the glass.
