Sunday, April 14, 2013

Joint Fillets

After the epoxy set on the joints overnight in the jig I removed the frame, checked the alignment and weighed it.  766g is a pretty good start to having a nice light frame.
Before I wrap the frame in carbon I add fillets to smooth the joints between the tubes.  These are made out of 50 micron glass balloons and DP420 epoxy.  I did a quick test in the oven prior to this build and found a newer, easier to mix laminating epoxy went soft below 250F.  I did not want to risk having it move under vacuum so I used the same method I have on all the frames so far.  Here is the BB sanded.
Another view of the sanded BB joint.  I'm trying slightly larger fillets on this frame.
Similarly on the head tube, larger than normal fillets, mostly because the top and down tube almost touch.
Also trying a web between the seat stays on this frame.  It will help stiffen the joint and make the carbon wrapping a little smoother.  Here it is partially sanded.
Once all the fillets were sanded the frame came in at 788g, ready to wrap in carbon pre-preg.

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