Sunday, February 19, 2012

Joint Wrapping

I finished the fillets on Chuck's frame and prepared it for carbon joint wrapping.  The tubes near the joints are sanded with 80grit to roughen the surface for bonding then wiped down with a lot of isopropyl alcohol.
Here are the head tube and seat tube junction fillets.  I made them larger than on previous frames for smoother tube junctions.

I started the joints with 300g/m^2 uni directional carbon.  I use long pieces that wrap around the tubes from multiple angles.

New on this frame is the 2X2 Twill weave carbon.  It draped well over the joints and will add significant strength.

Here is the finished head tube joint.  The final layer is unidirectional long wrapping pieces with a  few cosmetic bits to fill gaps.
This is the first piece I add for the BB joint.  It has a lot of contact with the tubes spanning the whole joint.

I finish the first layer with some diagonal fibers for bending and torsional strength.

After a few layers of 2X2 Twill I finished the joint with some more unidirectional.
I used significantly more carbon forming these joint than in the past.  This will make for a nice strong frame with rigid tube intersections.  It added a little more weight but some of that will come off  when the excess epoxy is pulled out of the joints under vacuum. Still working though the "cosmetics" with each build.  This should be the nicest yet.  We'll see when it comes out of the oven in the next few days.
Coming up next, the frame gets vacuum bagged...

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