Adding Carbon Layers

 
 
 
The image above shows a section of the frame after all the carbon layers were added.    As for my previous build (Mistress), I used (mainly) biaxial carbon fiber sleeves from Soller Composites.  I applied three layers of carbon over the full length of the frame. Each of the three layers was applied in two sections (front and back), mainly because it was easier to handle shorter lengths of carbon at one time. The two sections of carbon in each layer overlapped somewhere in the middle, but I staggered the position of the overlaps so that there wouldn't be one section in the center of the frame that had six layers of carbon, and three everywhere else.  Otherwise it would have looked like a snake that just ate a rat.

In addition to the three layers over the full length of the frame, I applied an additional layer in the region of the head tube.  The head tube hole is a pretty big discontinuity in a region of the frame that is likely highly stressed, so I felt better having an extra layer there.  I applied this extra layer after the first of the full length layers.

The sleeves I used were the 4 inch and 5 inch diameter "heavy" sleeves, which have a finished thickness of about .022 inches.  I chose these relatively large diameter sleeves so that the fibers would be oriented preferentially lengthwise along the frame.  I used the 5 inch sleeves in the front half of the frame, and the 4 inch sleeves in the back, since the frame itself had a shallower profile toward the back end. 

The exception to this was for the front section of the second layer.  There, I used a 7 inch nominal diameter uniaxial sleeve. Since the bulk of the stresses are along the length of the frame, I felt using some unidirectional fibers made sense.  I actually intended to use the uniaxial sleeve for the entire second layer front and back), but I was not very pleased with how the front section came out, so I switched back to the biaxial sleeve for the rear section of the second layer.
 
 
 
Before adding the first section of carbon, I noticed that the frame was very slightly twisted.  I straightened it by curing the first section of carbon with the two aluminum tubes shown clamped to the steel rails.  This precluded the use of vacuum bagging for this step, though I did vacuum bag all of the following carbon layers.
 
 
 
 
The image above shows the frame after applying the first layer of carbon to the rear half of the frame, and vacuum bagging in the Foodsaver bag.

 
 

Here it is after unpeeling the batting and peelply, with the fisrt layer of carbon fiber completed.


 

 

 And the above image shows the additional carbon layer added in the head tube region.

 

This is the unidirectional sleeve.  Unlike the biaxial sleeves, the uniaxial sleeve has elastic fibers (white) that hold it togther and let it expand in circumference.
 

 The above image shows the frame after the unixaial layer was added.  As I mentioned above, I wasn't thrilled about how the uniaxial layer turned out.  What I didn't like was that after curing, there where gaps between the groups of fibers.  Maybe I should have used more epoxy.

 

And above is the frame after the third layer was added.


 And here's the frame, starting to look pretty nice, after several rounds of sanding and applying epoxy.

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