Tuesday, May 30, 2006

Light pressure

When using straight epoxy on the joint you have to do it in two stages. First mix up a batch of epoxy then paint the joints with it. Leave the resin to soak in for around 10-15 minutes. Come back and paint'em again, then put them together. Relatively light clamping forces are needed because you're not trying to squeeze out the thickened epoxy to make a tight joint. See the pic for my clamping rig. Just some pieces of scrap to spread the weight and some buckets of water as weights.
I will admit to one disaster with this setup. I had lost the piece of wood that I was using as a weight spreader and just grabbed another piece that was narrower. I put the bicket up there and the darned thing tipped over as soon as I let go of the handle! Curing epoxy looks very sad when it's mixed with water, turns all milky. I had to grab a rag and wipe all the water away then get a fresh pice to get all of the potentially contaminated epoxy out of the joints (I was doing two at a time). Anyways I got the whole mess sorted out and completed the joints.
At this point I'd say the lap scrfs have been a success. They are very strong and the joint conforms well to any bend in the ply. The main provisos I'd put on them is, careful jig setup and then careful fitting before putting any epoxy on them.


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