Builders' Forum Archives
Re: Help needed
Posted by Laszlo on Sep 4, 2007
That was a good call about redoing the joints. As Seth says, the thickener keeps the epoxy from flowing out of the joint. Unthickened epoxy is actually stronger than the thickened stuff, but if the epoxy flows out your joint may be starved and break. A flat joint, gently handled, may survive until the glass layers are applied, but now you don't have to worry.
For what it's worth, on small boats (all the boats sold here), wood flour by itself is all you need to add. It's a good thixotropic agent and will keep the glue from running without needing any cab-o-sil. Cab-o-sil's disadvantages are the funny color it gives to the glue and that it cures to an artificial rock which is a real pain to sand.
You only need to add as much thickener as you need to keep the glue from running out of the joint. Flat joints need very little, vertical joints need more and fillets need a lot and vertical fillets need a hell of a lot. So if at all possible, do your gluing and filleting flat. I like to tilt the boat, when safe and possible.
Finally, try to ease up on your perfectionism (or at least worring about it). Whatever happens, you are going to have a good looking, well performing boat. The process is ridiculously forgiving. It's not at all like regular carpentry or cabinet work. Epoxy fills gaps. Missing splinters are going to be invisible once the wood is sanded, epoxied, glassed, sanded and varnished. So don't lose your momentum over the small stuff. And even over larger boo-boos. Onlays can cover a multitude of sins. If worse comes to absolute worst, you'll have a lovely painted first boat and a knock-em-dead second boat.
In Response to: Help needed by Rich on Sep 3, 2007