Started wrapping the sisal twine around the joints tonight. Here’s the process for the seat-tube. I’ve done it in two layers. The first using lengths that run lengthwise down each pole, following the curves of each filleted corner. The second layer then holds these strands in place by wrapping around and around them. I finish it off with a few diagonal turns across the main joint and give it a haircut to neaten it up.
There’s no epoxy on any of this. I’m mainly practicing the wrapping process but am also considering making some sort of mould that I could then inject the epoxy into the sisal and joint as it is now. I’ve tried brushing and drizzling epoxy into twine like this before and then wrapping it in PVC tape to set and it sort of works, but due to the tightness of the wrap and the double layer it might need more pressure than what PVC can provide in order to make its way to the bamboo and not have any air bubbles in it.
Hey Mik, did I read something about saturating the twine in the epoxy before it is wrapped? An option for you is to use pvc plastic sheet to make yourself a vacuum bag that fits around the frame (With same sort of tape to seal it all up) fill with epoxy and vacuum tight. Not sure if it would work and you’d want to be careful to not fill the vac with epoxy but I have seen this done for making plywood over a curved former.