Excerpted from "International CanoesLetter", the North American Newsletter for the International Canoe Class Willy Clark, Editor and CSM Contributing Editor
There has been a great deal of emphasis lately on developing prefabricate boat pieces the goal of which is to create affordable parts that are also easy to assemble. This has lead to Christian Knott and Geoff Harman developing the Flat-pack method, an almost entirely pre-fabricated boat, which Christian will have describe in detail in a future issue. In addition Steve Clark has had somewhat of a breakthrough developing a laser cut sliding seat. ~ Willy
Laser Cut Sliding Seats
By Steve Clark
Maybe it’s because I never got to build many model airplanes as a kid, or maybe it’s because I like to think that there are clever ways to make it simple to build complex things…..( WHAT?)  But I have always wanted to design something that tabbed and slotted together and was strong and light but fundamentally easy to assemble. The problem I always had was making all the pieces accurately enough. Well the modern age of CAD/CAM has finally trickled down far enough for guys like me to get a taste, and it’s pretty cool.
The idea is simple enough, to build something like a sliding seat you need to reduce your design into a number of simple parts that, when socketed together, form a relatively stiff grid that is the shape of the object you wish to build. You then glue all these bits together and presto you have built something that you really didn’t know how to go about building. Thinking that the sliding seat was one of these tricky bits that made building the IC an even bigger challenge than it needed to be, I set to with AutoCAD and created the following: (above) it was then e-mailed as a DXF file to my friendly neighborhood Laser Cutter who turned a sheet of 4mm plywood into these parts. I vacuum bagged a layer of 70 g/m^2 Kevlar onto the back of the top along with three 1” strips of 300g/m^2 unidirectional carbon fiber on each edge. I get no points for being tidy, but the frame has been glued to the top. The frames in the way of the heel wells have been tabbed with carbon cloth to make sure they don’t go anywhere and are not likely to leak. Half of the bottom has been glued in place. (You get the idea.) Worthy of note is that the whole mess is being supported so that it doesn’t warp as it’s being glued together. Some creativity with clamps helps!  After the bottom is glued in place, the edges are tabbed together. On the bottom centerline four 1½” strips of 300 g/m^2 are laminated in place to finish the structure. I tried to get away with having the whole thing built without a power tool, but I had to put bull noses on the front and back to make it fit nicely in a carriage and also to soften the inevitable blows to the body parts. This required the use of a table saw and a pretty big router bit. Not a stretch for Norm Abrams, and I hope anyone seriously thinking of building one of these boats at least has a friend with a saw. Here it is, ready for the finish of your choice. They weigh a bit more than 8 kg (about 18lbs Ed), depending on your choice of nose wood and how tidy you are with your epoxy and tabbing. To date a few of these have been built around the world. |
