Been a while since the last entry, but I’ve been pressing on.
In the week or so before Labor Day I’d assembled the building frame that will provide a solid platform on which to assemble the boat at a convenient height. It’s not at all sophisticated, just two long 2×6 beams and a series of cross-members. Unfortunately, in spite of my best efforts, it ended up with a twist at one end. So the corner nearest you in the picture is high by a bit less than 1/4″; more than I could take out by shimming it around. One of the main points of the building frame is to provide a level surface for the temporary forms to sit on, so this is not ideal. I briefly contemplated starting over, but decided instead to just cut the top surface down as required in the area where the last mold will get set up. The molds will need to be checked and fine-tuned anyway one they are set up.
Nevertheless, I needed to level it as best I could, which I did by building a water-level out of some scraps of wood along with a length of tubing and a couple of stainless-steel rulers from Home Depot. For those unfamiliar, the principle of operation is that the tube is (mostly) filled with water with the ends left open to the air. The level of the water in each end of the tube will always be at exactly the same height.
This arrangement worked pretty well to get the level close over the length of the frame (save for the aforementioned defect). The only headache was that I think the inside of the tube on one end became contaminated with something so that the meniscus was considerably deeper at one end than the other, making reading it tricky. I compensated by factoring in the offset when the two ends were set up next to each other on the same surface and double checked measurements by swapping the two ends. Hopefully, it’s Good Enough™.
Then it was time to set up the molds set up at their locations; check that they were perfectly (haha, sure) vertical, level, and square to the centerline; and brace them in place.
You may notice that two of the molds still need to be braced. That is because I decided to spend yesterday FINALLY making a part that will stay on the boat. First up is the inner stem (described in a previous post) which is laminated (glued out of many strips bent around a form). I am using Douglas Fir which is fairly strong and not too heavy and takes epoxy well.
I used a circular saw with a home-made ripping fence to cut strips 3/16″ wide.
The form is blocks of wood screwed down around the curve from the pattern I made from the lofting. This picture shows the form with the strips temporarily dry-fit to practice getting it clamped up and to confirm that the strips would bend without breaking (in fact one did; fortunately I’d ripped a couple extra). Once mixed, the epoxy starts to cure in the pot within 20-ish minutes, so taking the time to work through the process once before it was a race against the clock seemed wise.
After laying down some plastic sheeting and taping the form blocks and clamp pads with packing tape (to avoid the form and the clamps becoming part of the boat), and making sure everything needed was handy, I was ready to go.
15 frantic minutes later, including a minute or two of panic when I found I hadn’t mixed enough epoxy to begin with and had to whip up another batch with the strips partially coated, and the die was cast.
There was a bit of sweep in the original board that the strips came out of meaning that the strips don’t lie perfectly flat along their edges. I flipped every other strip over so there wasn’t a bias towards one direction in the final part and crossed my fingers that I could tap them down flat (hence the mallet) and that the friction (even slathered with epoxy) would hold them there while it cured. I’m not sure I got it totally flat, so some trimming may be required. Hopefully not very much as the width of the strips is already pretty much the minimum required to get the intended final width of the part – a limitation based on the available size of lumber I could get without a lot of resawing and planing which I don’t really have the equipment for.
The acid test will come after a day or so when it’s cured completely and I can pull it off the form.
You’re not supposed to clamp epoxy laminations too tightly for fear of squeezing all of the goo out of the joint. That’s a good thing because tightening all those small round clamp handles much at all with slippery epoxy-gloves was nearly a lost cause. I did manage to get it pulled in to the form, but it was a pain. The quick-grip clamps like this might be a better tool for this job.