Inner Stem Mohawk

January 10, 2013 § Leave a comment

I know that I said that I wouldn’t overdo the posts this time around, but forming the inner stem is always a momentous occasion. Your forms are in place and you’re finally building.

The last few times, I was able to use three standard 1/4″ strips to make the inner stem. This time, I was rewarded by the sound of cracking wood as I bent the strips over the form. Deciding that I didn’t want to hear that sound again, I planed four strips a little thinner and then (as last time) soaked them in the tub in hot water for over an hour.

This time, the strips bent well and the end result was a beautiful inner stem mohawk shown below.

inner stem

By the way, I use Gorilla Glue for this part. It reacts nicely with the damp wood and gives a good bond.

Starting the football

May 14, 2011 § Leave a comment

There comes a point when it’s no longer possible to affix strips to the internal stem. Stripping the resulting opening — the football — can be accomplished in a variety of ways. Many builders strip one half of the football, cut the excess along a straight line, and then finish the other half. It’s a nice effect when done well, but falls apart if the two halves don’t match each other perfectly.

I’ve opted for a different method for the following reasons:

  • Cutting a straight line gives me the willies
  • Matching wood between the halves is more difficult if you lack the foresight and planning required (as I do)

Instead, I’ve opted to run two strips along the centerline and then fill the halves using a herringbone pattern.

The advantages are:

  • The two strips form the straight line that I want
  • It’s easier to match grain and color by working on one half of the canoe and then the other

cedar strip canoe sides

Running the two center strips requires some careful beveling as the hull at the ends have a pronounced angle. Towards the middle of the football beveling is less of an issue as the bottom of the canoe is relatively flat.

Here are a couple of other notes on running the center strips:

  • Clamping the strips together here is overkill. More likely than not, the pressure of the clamp will prevent the strips from lying flat against the forms. I’ve found that taping the strips together with masking tape is more than sufficient to hold them together until the glue dries.
  • It is crucial that you measure the distance between the edge of the football and the center strips at each form. Any discrepancy between the halves will be accentuated as you fill them in, particularly if you’re planning on using strips of different colors as accents.
  • Although I have opted for stapleless construction, this is one place (among a few others) where I do tack the strips to the forms. It is easy to alter the position of the strips when filling the football, so securing them is a good idea.

Here’s a picture of the football with the center strips in place:

centerline of football

Now for an admission of fallibility…

You’ll notice that the center strips don’t align perfectly with the strips in front in the picture above. On measuring the distance between the sides and the centerline, I noticed a small discrepancy (less than 1/8th of an inch) between the sides. Fudging the strips (as above) corrects the discrepancy. Fortunately, the external stem will cover and disguise the adjustment.

On another note: After stripping the canoe with bead and cove strips to more easily navigate the curve of the bilge, I’ve transitioned back to square edged strips. I’ve found that using bead and cove strips when filling the football tends to damage the cove, particularly if you’re fiddling around with adjustments and dry-fitting the strip multiple times. Running a rolling bevel for this part of the build is less aggravating (for me, at least).

Building the internal stem

January 21, 2011 § Leave a comment

Internal stems are what the strips are attached to at the bow and stern. They can be made out of a solid piece of wood, but it’s easier to laminate several strips. These strips are bent around the bow and stern forms. When you’re stripping the canoe, the stem gives you a good surface to glue the strips to at the ends. Internal stems are also important in terms of strength and helps the canoe better handle impact.

Because the internal stem is hidden within the boat, its appearance is less important than that of  the external stem. As a result, I’ve decided to experiment.

I had some strips of white cedar left from the previous build. The stock is perfect for the internal stem in that its soft and bends easily. I’ve also used pine in the past. I don’t have a steam box and don’t really feel like building one. That said, I know that cedar typically responds well to the heat gun. It’s still a little nerve-wracking to wrap the cedar around the bend of the form, expecting at any moment to hear the tell-tale crack of wood that has been overstressed.

For the first internal stem, I stack 3 knot-free strips of 1/4 inch white cedar. Instead of doing one strip at a time, I apply glue between all of the strips at once and apply heat. I gradually tighten the strips against the form, heating all the while.  Just as I tighten the final clamp, I hear the wood splintering. When I investigate, there are a series of small splits in the wood on the edge where material. Because the edges will be planed off anyway, I decide to leave it.

For the second stem, I soak 3 cedar strips in water overnight. The theory is that since it’s the dead of winter, the first strips have dried out somewhat. Soaking them will hopefully allow them to absorb moisture and make them easier to bend, particularly with the addition of heat. I apply glue (Gorilla Glue, in this case) to the strips and stack them. I clamp the stack to the end form as follows…

canoe building: bending the internal stem

…and add more clamps and pressure as I work around the curve. No splintering. In fact, the wood is bending smoothly and easily.

The final result looks pretty good.

canoe building: bending the internal stem

Note that I’ve taped the form. This is to prevent the stem from sticking to the form. Before I begin stripping (the canoe), I’ll tape the edges of the station forms as well.

I’ll let the stems dry before planing the edges and mounting the end forms to the strongback.

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