Monday, July 20, 2009
I managed to get my forms cut out of the Occume plywood. My friend got her forms cut out as well and took them home to sand and finish. This is a fairly straightforward process. We tried to approaches to cut the outer profile - a jig saw with a 20 TPI blade and a bandsaw. In lots of regards, I think the jigsaw was actually easier than the bandsaw as we lacked the throat depth on a 14" bandsaw to get at all of the features without using the jigsaw to finish. We used a 3/4" Forstener bit to clean out the corners on the inside and to allow us to start the cut on the inside of the frame where we used a jigsaw regardless of how we cut the outer profile.
After the forms were cut out, I took a 1/8" radius round-over bit in a palm router to ease the inside edges of the forms. I figure I don't want sharp corners where it may touch either the paddler or dry bags to avoid chafing and potential punctures. It will also help the finishing process. I also eased the sharp corners between the stringer notches with a little sandpaper. This is the end result.
I used the same 1/8" radius roundover bit to radius the corners of the stringers. Again, to keep from having sharp corners in contact with both the paddler and the Dacron skin that will cover the boat.
We also constructed two strongbacks - relatively simple - a 12' 2x4 for the top plate and another 8' 2x4 set on edge and screwed to the top plate to keep it from warping. On the top surface, the form locations were marked out. The two end mounts (rectangular pieces with a vertical slot in yesterday's post) were attached to the top of the beam using 2x4 blocks. It is important to remember that the forms are spaced to the same side, so one of the end mounts has to be offset by the thickness of the form stock - in this case 1/2". Here's one end of the strongback.
The strongback was placed on sawhorses and the form 1 and 6 were attached to the end mounts at the proper height, leveled from side-to side and clamped in place. Once this was done, the sheer stringers were installed using bungee cords. I was suspicious of the reason for bungees instead of clamps, but the bungess let the stringers slide. This isn't apparent unto the next step. Extra hands or clamps, however, are good for holding the stringers in place until you can put the bungees on. Unless you are an octopus, this is not easy. Here are forms 1 and 6 with the sheer stringers in place.
This next step is really made easy by this next tool - a Quick Grip clamp/spreader which when set up as a spreader will push the stringers apart so that you can install form 3 in between the stringers. It's a great tool.
The next step is to install the forms between the stringers and ensure that they are vertical, perpendicular to the centerline and at their correct spacing. Not that difficult really. Once this has been done, mark the stringers on either side of the form. After that is done, the chine stringers and the keel stringer are installed. Once I tried this, I had some issues I'll talk about later. Time to retreat to my thotful spot.
Well, at least there was a little progress this evening - not much, but a little.