By James A Morikawa
Hello Daniel, Here's some pictures I promised you. I don't have too many of them. I hope they help clarify what I wrote about.
The bottom bracket in the lay-up process. At the top you can see the first layer of carbon. The bottom still has the "peel-ply" covering the carbon layer. This "peel-ply" can be peeled away once the epoxy hardens. Then I start the laminating process over again, to do the second layer, then the third, and so now. It's a slow process due to the long curing time of the epoxy I'm using. Maybe someday I'll use "prepeg" carbon/epoxy, which is heat cured, a more involved, and costly process. It would allow me to get a carbon matrix with higher bond specifactions, and I think it would speed up the process. The epoxy/hardner system I'm using, once cured, you don't want get the frame in a situation were the tubes get hotter than 180 degrees F. Like, don't ride it in a swimming pool of boiling water. The epoxy matrix will start to loose some of it's tensile strength, of course it will regain it when it cools.. Sort of like when you get some plastics too hot. All that said, I feel it's a "plenty strong" epoxy for the job.
With the peel-ply I'm able to squeeze out the excess epoxy, and air-bubbles, using pieces of "breather cloth" to press and absorb with.
The BB still in the build-up process. In this picture, I believe it has about 5 layers of carbon. The aluminun center has one layer of fiber-glass, to help control galvanic corrosion. The aluminum headtube sleeve also have a layer of fiber-glass.. I've machined them down to cut down on weight. Better to use titanium as sleeves.
I tried a brand of "peel-ply" I purchased from "Aircraft Spruce". It didn't "work" as easily as the type I purchase locally from "Fiber-glass, Hawaii". I like the locally purchased stuff because it's thinner and lays the carbon smoother around the contours. Just works better for me.
Here is the Head tube joint in progress. Easier to do than the BB.
Getting there. I use a putty of "micro balloons/epoxy" to fill in the voids.
This frame came out OK. It could have been done better. I painted the joint-areas a faded black. I left the carbon weaves showing at the center of the tubes.
There are a number of good technical books on the carbon-fiber subject. I suggest their reading. Sorry, but I don't have specific titles, and authors right at this moment.
I'm going to end off here.