Monday, October 6, 2008

Strongback and Ama Form Frames

After some time spent culling through the stacks at the lumber yard, I now have a strongback and form frames standing. We built the strongback, or the base of the building site, out of 2"x6" dimension lumber. Ian's plans called for 1"x6", but I thought this might be too flexible and I really wanted to make the strongback bulletproof. I think it paid off and the cost of dimension lumber at 2"x6" was slighly less expensive than 1"x6" clear material.

The strongback is completely level, square and plumb by use of a transit and plumb bob and ordinary level. We shimmed the legs of the strongback to the correct height or filed down the strongback sides to attain level and plumb within a tolerance of 1mm, measured by the transit.

The form frames were lofted from the full-size patterns provided by Ian. We cut each sheet of MDF to a working dimension of 22"x48". The width (48") is not that important, but the height needs to be exact for each frame, so the 22" is right on the money. Once the patterns were lofted, we rough cut the curves with a jig saw and then sanded them down to the line.

One suggestion for new builders is to rip the MDF approximately to width (22.5") and then make a second cut exactly to width (22"), hopefully using a feather stick on the table saw to keep the material tight against the fence.

The greatest part about this process is that once you get the form frames standing, the shape of the ama is immediately apparent. You can almost envision the hull you're about to build, sitting nicely within the frames.

The pictures below show the beefy 2"x6" strongback, the assembled form frames and a light at the end of the tunnel!

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