Tuesday, December 22, 2009

Not quite Tech Tip Tuesday

Today's post is a bit about what we've got going on in the shop where I teach. As we're winding down for the end of the Fall session, I've got boats in almost all phases of construction. I've got solo boats, a tandem boat and a sea kayak. My students ask me how I can keep track of things at the various stages, but it's getting to be second nature.

As you may remember from an earlier post, the couple building the tandem had cut and glued up the feature strip for their canoe. It came out rather nicely. At this point, the strip is about 2" wide and almost 7/8" thick. The pattern that you see on the face runs all the way through the stock. As I may have mentioned before, the blonde wood is carefully selected Poplar (Carefully selected to avoid the greenish streaks that Poplar can have.) and Peruvian Black Walnut - a very soft variety.

Because I have so many novice woodworkers in my class, we choose to use cove-and-bead joinery to ensure ease of assembly by my students. Unfortunately, I think that if we did hand-beveled strips, many of the students would be good at it by the time they were about half-way through their canoes. As we are interested in improving the speed of assembly and limiting the amount of final fairing and sanding, cove-and-bead seems to be the way to go. It isn't perfect as there are some points where the bend and twist of the hull make it difficult to keep the strips well seated, but this isn't a "show stopper". The strip you see above is thick enough to allow us to plane the surface that will show flat using a thickness planer, to remove any steps in thickness that have occurred during the gluing process.

This flat surface is important. We want this flat surface to run against the fence on the table saw. Using our piece of 1/4" aluminum bar stock as a gage to set the spacing between the table saw blade and the fence, set featherboards on the fence and table and we cut off two 1/4" thick feature strips. We are left with a scrap that is usually about 3/16" thick that would be ideal for inlay in a deck or for a detail on paddle blades that would match the feature strip on the hull of the boat.

The next step is to set up the router table. I've discussed the router table here before. (Side note : The router table gets such hard use that I've been designing one to have made from aluminum tooling plate with micro-adjustments to make set-up easier. I've been thinking I should write an article on the subject...) Because we only have two strips, we can't afford to make mistakes. What we do is to make two or three "dummy strips" from scrap that are about 18-24" long and are exactly as wide and thick as the feature strips. Using this, we set up the router table and mold cove and bead on the feature strips, winding up with this profile:

While this is a great way to get out feature strips, it's a bit time consuming. One caveat about making feature strips this way (i.e. off the forms) - a strip about 1-1/2" to about 2" is the maximum width depending on the amount of curvature that the hull has to avoid getting poor transitions to the remainder of the hull.

One student is finishing up the final details on her boat. The decks, thwart and coamings are in and the seat frame is to be mounted before final sand and varnish. In the picture below, this Wee Lassie II is getting seat blocks installed. I prefer to use either 4 seat blocks or two frame rails set in "Dookie Shmutz" (Thanks, Nick Shade, great name for the stuff! ) which is epoxy thickened with wood flour and fumed silica to a peanut butter consistancy. The process we use is to install a dummy seat and clamp the blocks to the top of the seat. Using a compass, we scribe the hull curve on the blocks and cut them out on the bandsaw.

The big trick here is to get the seat level side-to-side, at the balance point of the boat, far enough forward that the thwart isn't in your back and the seat tipped just a little bit forward to take the pressure of the back of your thighs when paddling. I also like enough clearance under the seat frame to get my hand under it to clip the straps on my Crazy Creek Canoe chair together. Makes a nice back-rest when paddling. We then screw the seat frame to the blocks. I do this to allow the builder to get the frame out for re-caning in the future.

The other boat that's coming along is the Osprey kayak. Although this photo doesn't do it justice, the deck is a shapely an sensuous curvature. There is a center strip of Butternut and the whitish island is Port Orford Cedar with it's lovely citrus-ey smell. The vertical element of the coming will also be Port Orford and the cap and coaming rim will be more of the Butternut. She's going to be a very pretty 'yak.

If you're wondering what the object is in the foreground covered with foil, it is a pan of brownies. My Saturday morning classes include what we refer to as the "10 o'clock Union Break". This is actually a very important part of my class. At 10 AM, we turn off the power tools and take a break to have coffee and snacks. We use this "quiet time" to bond as a group and to answer questions and solve problems that the students may have. It also gives the students a rest so that they returned refreshed and re-energized to do more great work.

Never underestimate the restorative power of coffee and a donut!

No comments: