Friday, October 2, 2009

Building A Small Pack Canoe: Part 7 - Trim Work

Finally, we had a hull. All we had to do was turn that hull into a boat. There was still a lot of woodworking to do at this point, most of it more exacting than anything we had already done.

We had to fashion and secure two sets of gunwales (pronounced "gunnels"). Gunwales are the rails that run along the opening of the canoe. Each set is composed of an inwale and an outwale (curiously, pronounced "in-whale" and "out-whale") that work together to strengthen and stiffen the fragile and flexible top edge of the canoe (called the "sheer").

Since we had purchased plenty of extra basswood, we only used the lightest color boards for the stripping of the hull. We had one darker board that was knot and check free for its entire 12' length. When we ran that board through the surface planer, we received a very pleasant surprise. The entire board had a faint but very beautiful curl to it, almost like a fiddle back. We cut four strips out of it and planed them to 1/2" x 3/4" x 12' long. We knew right away that they would provide a stunning accoutrement to our little boat.

Here's a shot of the gunwales being planed to a taper at both ends. By tapering the ends, we would lighten up the looks of the boat (as well as dropping about 3/4 of a pound), adding a touch of elegance without weakening it in the slightest.

We found a bunch of very robust spring clamps (green grips) for $1 each at Home Depot. As they say, you can never have too many clamps.

The plans called for the gunwales to be glued with epoxy about 1/8" down from the top, and then to trim off the excess planking once the glue had cured. Previous experience (and lots of reading) told me to allow the natural curve of the bent wood define the line of the sheer, but Lady BK and I got into a bit of a disagreement about this. As usual in these cases, the little lady came out victorious. I allowed her to set the gunwales exactly 1/8" below the top along their entire length. The result was that they followed every irregularity along the sheer. This was not in the least apparent since all the spring clamps obscured the line until they were removed after the glue had cured.

If you ask a hundred boat builders what's the most important line to get right, every last one of them will say it's the sheer line. We had just completely blown the most important line in the canoe! A lot of work with sharp block and shoulder planes, together with some very careful observation while re-cutting the tapers in situ, would eventually resolve 95% of the irregularity. At this point, however, I was sure we'd have to cut the gorgeous gunwales off and replace them with wood that was much more boring.

Next on the list were the outer stems. These were laminated ahead of time and fitted to the end of the boat. They were glued in place with epoxy resin thickened with sawdust. Fitting them to perfection wasn't a big deal for me, but carving them to shape so they were harmonious with the rest of the lines of the canoe was a bit of a challenge. The first stem took almost two hours to figure out and shape. The second one took about a third of that time.

Lady BK is shown sanding the edges of the gunwales with a small concave sanding block. I had used a small block plane to cut a nice, even 45º chamfer on each edge beforehand, so all she had to do was to blend the facets into smooth curves.

Now it was time to make and install the breasthooks. No, breasthooks aren't those little fasteners that hold a bra strap together. They are small, triangular pieces of wood that tie in the inwales and the stems. Their shape and placement adds significantly to the looks and strength of the ends, so their construction and installation are important.

We had on hand about a dozen fancy black cherry burls that I had salvaged from my firewood pile. We chose one and cut a couple of slabs out of it about 1/2" thick.

The rough breasthook slab is worked in my small patternmaker's vice to put a slight crown into it, both to shed water better and to add a certain sexiness to it that only curves can do.

A breasthook is trial fitted before gluing. Even though we would use thickened epoxy to glue it in with, I made sure that the sides fit perfectly with the rails. Little details like this only take about five extra minutes and will be there forever to remind you and everyone else how refined your sensibilities are.

Spring clamps and a few clamping pads were all we needed to get the top perfectly aligned while we clamped the breasthooks in place with a small bar clamp.

A bleary-eyed Lady BK laminates yet another strip of bias-cut glass cloth over the gunwales. This will ensure that the relatively soft basswood won't wear through anytime soon. Even if it does eventually wear, a new strip of glass could always be added to the worn area at a future date.

A detail shot of the breasthook and rails under three layers of resin.

Two support thwarts were fashioned to fit at the quarter positions. Here I am using one of my favorite power tools, the oscillating spindle sander. It goes up and down as well as spinning around, leaving a very even finish with no grooves or burn spots. With an 80 grit drum, it's fast as hell, too.

We cut chamfers on the edges of the thwarts to lighten them, but mostly to make them more elegant looking.

Here they are with two coats of epoxy on them. All that's left now is to apply five coats of varnish to everything and fit the seat and backrest. Then off to the water with her for her maiden voyage.

Thursday, October 1, 2009

Building A Pack Canoe - Part 6: Fairing And Fiberglassing The Interior

Now that the canoe was off the form, it was time to work on the interior. To do that, we needed a set of holding cradles...

Remember back when I told the story of my eye injury? Well, it was cutting the wood for the cradles that did me in. I eventually finished them, but I know exactly which piece (one of the bottom cross members) originally held the errant wood chuck before it came flying at me, so every time I look at it I get a grim reminder to be more careful.

Anyway, working on the interior is just about twice as hard as the exterior. Not only is the canoe no longer firmly attached to the form, you have to work inside a confined space that is all concave in cross section. That meant that the same tools we used on the outside would be of limited use or downright useless on the inside. A block plane was out of the question, there were only small sections that provided access for my 6" RO sander and long sanding blocks were only helpful for sanding along the length of the canoe. I have some tools that would be considered kind of exotic to the average canoe builder, but (sorry) you go to war with the army you have. I happen to have a pretty nice army.

First off, though, I had to make a tool that would waste away most of the wood. After looking at many books and websites, I found most everybody's solution for interior scraping to be less than desirable.

This is the tool I came up with to scrap away the glue (there will always be much more glue on the inside since you can't easily wipe off the excess while the boat is still on the form) and do the bulk of the stock removal. I wanted something that was both robust and could be pulled along with two hands without digging in too much. I rounded the edge of an old plane iron and screwed it at an angle to the end of a long hardwood handle.

Here it is in use. The end of the handle rests on the surface and the tool is dragged backwards. It made quick work of wasting away about 90% of what had to be removed.

Having a musical instrument building background, I tend to take that kind of approach for much of my other woodworking. A small canoe like this is not much smaller than an upright bass fiddle, so it was inevitable that I would use similar tools and methods as would be used in the construction of a bass.

This is a small scrub plane that I made several years ago for hollowing out archtop jazz guitar tops and backs. It is made from a piece of mountain mahogany (very hard and dense wood), a 1/4" thick slab of silicon bronze and an old file that I heat treated and ground for a blade. The bottom has a gentle arch that just happened to match the curve of the inside of the canoe nicely. It is a roughing tool and it really hogs away a lot of wood in a hurry.

This is a commercially available (through instrument making suppliers) convex bottomed plane that has both smooth and toothing blades and an adjustable throat. It is prohibitively expensive, but I already owned it so I used it. The toothing blade has grooves milled into the back face. This allows you to take cuts in any direction without tearing up the wood fibers

This close up shows what the tool marks look like when the toothing blade is used. It cuts shallow grooves in the wood that are easily sanded out. By crisscrossing back and forth, a very fair surface in easily obtainable. Its ability to cut just as well across the wood fibers as it does lengthwise makes this plane a winner for this operation.

Here's a shot of Lady BK deep in the moment while working on the end of her canoe. I'm sure she was thinking, "If I knew this $**{!#@ canoe was going to be this much work..." Still, she slogged away admirable.

This photo shows how much wood we scraped and planed away before the final sanding. I weighed all of those shavings for future reference. They only weighed 11 ounces. A quick computation told me that we had removed about 8% of the remaining wood during the interior fairing process, so I guess my original estimate was pretty much spot on. This kind of info will be useful for future ultra lightweight projects.

Now we were down to 11 pounds for the bare hull before glassing the inside. After the final sanding and vacuuming, the inside was ready for us to apply the glass.

Because of the vee-shaped hull bottom and tumblehome/side junctions, we decided to add an extra layer of fiberglass to protect these areas. We cut 2" wide strips along the bias (45º angle) of the cloth weave. We used shorter scrap pieces and overlapped the ends by about half an inch for continuity's sake. This saved us from having to waste large amounts of good glass. I would have preferred uni-directional glass cloth for this application, but I knew the bias cut would be plenty strong enough.

We epoxied these strips into place as you can see here and let them cure overnight. We then sanded the edges to a feathered edge so that the glass laminated over them wouldn't get cut through when we sanded it out.

Next was a football shaped piece of glass to further reinforce the inside of the boat. Conventional wisdom dictates that smaller pieces be placed over larger pieces to avoid sanding through the larger piece during the finish sanding of the laminate, but we knew we weren't going to get anywhere near as fussy with the inside as we were with the outside. No matter how much you care for a canoe, the inside is always going to get abused. You can avoid bottoming out on landings and hitting rocks, etc., but you will always be on the inside, wearing away at the surface. Given that fact, and the fact that we weren't going to use a gloss varnish for the inside (so little things like seams weren't going to show), we decided to go for the easiest way to apply two layers of cloth simultaneously. We knew that the smaller football shaped piece would get dragged around by the heavy squeegeeing we were about to do, so we trapped it underneath the larger piece and made sure we didn't sand too aggressively when it came down to smoothing the interior.

Here's the cloth laid along the inside of the boat and dry brushed into shape.

The ends were slit to allow the cloth to fit around the inner stems and a little vee-shaped "dart" was cut out to allow the end of the cloth to butt up against the stems. Later on, we would put 4" wide pieces of bias-cut cloth over the stems and resin them in place.

At long last, with all of the fairing done and the glass laid in and wet out, we had a hull that would remain stable as we worked on the fit and finish work. We added another light coat of Clear Coat to fill out the weave a bit, but we made no attempt to get the surface as smooth as the outside would need to be. A slightly rough surface on the inside is actually a help in eliminating slipperiness, and since it won't be touching the passing water, it won't create excess frictional drag like it would if we left the outside this way.

After the resin was hard, I used the same 2" slick to cut away the excess glass and then bagged it up to use as clean scraps for the glassing of trim, etc.

We weighed the boat at this point and found it was a fat 14 pounds. With the extra glass on the inside, I figured there was about 15 oz, of glass and 15 oz. of resin, for a total of about two pounds. The extra pound was resin that either was absorbed by the wood (no getting around that) or the little bit of resin that we filled the weave with (one 6 oz. batch).

Wednesday, September 30, 2009

Building A Pack Canoe - Part 5: Applying The Fiberglass And Epoxy Resin

OK... I messed up by not taking any photos of the outer fairing process. Fairing is the procedure for making the hull of the boat smooth and free from bumps and hollows. No matter how carefully the strips are glued together, there is a little ridge at each strip juncture due to the fact that the strips are flat and they are going around a curved shape. The result is that the surface of the canoe is composed of dozens of facets that all need to be very carefully blended together to get a smooth skin.

We used many tools to perform this operation. First, we used a fine rasp to break off the excess glue that oozed out of each joint. Then we used a small block plane to cut the apex of each ridge and finally we used a combination of cabinet scrapers, power sanders and hand sanding to get the hull surface perfectly smooth and fair. This is just about the most exacting part of strip building, and with a strip thickness of only 1/8" in places, it was imperative that we take our time to avoid sanding right through the hull in spots. This is also the reason why we took so much time getting the strips as level with each other as possible when we were applying and gluing them.

Since the boat is primarily convex on the outside, bumps are what are sought out and hollows are left untouched until the last sanding step. We spent as much time inspecting the surface for bumps as we did scraping and sanding. The job was done when we could see no irregularities anywhere no matter where we placed the work light. At this point we used a paste wood filler to fill all of the holes and gaps, let it dry and then sanded the hull smooth. We then used a shop vacuum with a brush attachment to clean the surface of dust and we were ready for applying the fiberglass.

We cut off 12' of fiberglass cloth (3.2 oz./yard) which left 6" at each end. The cloth was draped carefully over the inverted hull and smoothed out, leaving the excess hanging below the hull.

We used a 4" bristle brush to push the wrinkles out of the cloth. As we brushed, not only did the cloth lay on the boat wrinkle free, it actually clung tightly to the hull surface. In this photo, you can clearly see the wood through the fiberglass cloth.

At this time, I turned on two electric heaters to warm up the room to about 80ºF and let the boat sit in the warm room for several hours to heat up. The idea was to keep any air that got trapped in the wood or under the cloth from expanding and creating bubbles. After we wet out the boat, we turned the heaters off to allow any trapped air to contract, thereby preventing any bubbles from forming. This also allowed the exposed wood to soak up
more resin as the hull cooled overnight.

This is how tightly we got the cloth to lay against the hull by brushing it with a dry brush. This would be critical to the ease we later enjoyed when we wet the cloth out with epoxy resin.

We used System Three Clear Coat epoxy resin with the slow hardener, which gave us plenty of time to work the resin before it began to harden. Clear Coat was recommended by many experienced builders as a wet out coat. It is a high quality, low viscosity laminating resin that readily soaks through the cloth and into the wood below. Since the fiberglass is composed of real glass fibers, the cloth virtually disappears once the resin is poured on.

Here is a shot of Lady BK applying the resin onto the hull. We began by thoroughly mixing up a small batch (6 oz. resin to 3 oz. hardener) and pouring it all at once onto the surface at the center, then spreading it downward and out toward the ends with a 4" chip brush. The less resin you use, the closer the cloth will adhere to the hull, making it both stronger and lighter. However, since the resin will soak readily into the wood - particularly porous woods like basswood - care must be taken to make sure that there are no chalky looking areas that indicate the the cloth is starved of resin.

We kept applying more batches of resin and spreading it out until the entire surface looked uniformly shiny. Then, using specialized soft rubber squeegees, the excess resin was scraped from the surface until the entire boat had lost its shiny look and had a dull sheen to it. Shiny areas mean there is excess resin which must be removed. Excess resin means the cloth is partially floating within the resin and not stuck firmly to the hull. Care must be taken to get every bit of resin removed from the surface before it hardens, but you also have to continue to watch for chalky looking areas that indicate that there is too little resin for good adhesion.

The resin/hardener combo we used hardens in 9 hours, but we gave it 24 hours to get hard enough to sand. We sanded the hull enough to knock off the gloss and then applied a second coat, this time with the regular (more viscous) System Three resin. A third coat was applied in the same manner, but more heavily that the second coat. This coat - known as a "hot" coat - was allowed to flow in a continuous sheet and onto newspaper that had been placed beneath on the floor.

After another 24 hours we began to level the epoxy coat with a sharp cabinet scraper. I can think of no more effective way to remove partially cured epoxy than with a cabinet scraper. It is simply a square piece of spring steel (an old hand saw blade is perfect) that is honed to a 90º edge and then a small hook is burnished on the edge with a smooth screwdriver shaft. When bent between the hands and held at the correct angle, it removes wood or resin just like a plane does - in thin shavings. The beauty of it is that it can be used when the resin is too soft to sand. Partially cured resin gums up the sandpaper quickly. For the sanding that was done in between resin coats, I used two entire sheets just roughing it up for the next coat. On a safety note, partially cured epoxy releases fumes into the air when heated through sanding, so you need to wait until it is fully cured before you power sand it.

This is a close up of a hand scraped area. Note the ridges left in the surface. It is almost impossible to get epoxy to flow out without irregularities in the surface since it is so thick. All I was trying to do at this point was to remove as much of the high spots as possible while the resin was still somewhat workable. There would be more epoxy and glass work on the outside later, so for now I just wanted to get it relatively smooth and then finish up the final sanding after a full cure had been achieved a few weeks later.

Here I am using a RO sander (slow speed) to do a quick blending of the surface left rough by the scraper. I should have been wearing a respirator, but as you know by now, I can sometimes be a bit lax when it comes to safety procedures. Even though the System Three products I was using are considered very low in toxicity, I strongly recommend a chemical respirator if you are sanding uncured epoxy.

Finally, the hull is off the form. I cut off the excess resin-soaked cloth with a 2" slick. It peeled off like butter under the mass of the heavy tool. The individual section molds were then detached from the strong back and knocked toward the center of the boat to free them from the hull. I decided to see how the weight was doing, so I improvised this setup to check it out. Subtracting the weight of the support stick and string, the hull weighed 11 pounds, 11 ounces.

Earlier calculations had led me to believe the hull might weigh as little as 10-10 1/2 pounds at this point. I had mixed up 36 oz. of resin in total and squeegeed off a weighed 7 oz. With a surface area of about 29 square feet, there should have been between 9.5 and 12 pounds of wood in the stripped hull (depending on the actual density of the wood) minus what was faired off (maybe 5-8%, or about 8-12 oz.). 29 sq.ft of 3.2 oz. cloth should have weighed about 10 oz. A 50/50 ratio of cloth to resin by weight is considered good laminating technique, so there should have only been about 10 oz. of resin in the glass at this point plus whatever soaked into the wood. I ended up using an extra 19 oz. due to the absorption of the resin by the very porous basswood. This was unacceptable when trying to build an ultralight boat, but I had to live with the fact that the boat would weigh a full pound more than I had hoped... and I still had to glass the inside. Future boats will be made from much lighter and less absorbent northern white cedar.

Friday, May 23, 2008

Building A Pack Canoe - Part 4: Stripping The Sides and Bottom

After we cut the tumblehome edge down to the scribed line and trued it up with the shoulder plane, it was time to start adding on the basswood strips that make up the rest of the hull. These strips were slightly thicker (5/32") than the walnut strips in the tumblehome area. To put the first strip on, we cut the edge of the walnut so it ran 90 degrees to each station mold. We then blended these together into a rolling bevel.  This meant that the square-edged basswood strip would fit perfectly to the walnut edge as it bent around the curves of the hull.

As with the walnut strips, we used a combination of nails, tape and clamped Plexi to get a good glue line. 

At this point, we decided it was easier to cut the rolling bevels on the strip that was to be glued on next rather than the strip that was already in place.  The next photo shows a couple of simple jigs we made to hold the strips while I planed the bevels.

The stripping proceeded rather routinely for the first 3 courses. At this point, we were able to employ another clamping aid which was simply small 2 x 3 squares of plywood with a notch cut in them so they would fit over the preceding strips. These squares were faced on one side with 80 grit sandpaper so they wouldn't slip. They were held to the station molds with a spring clamp and then tapped down with a mallet to close the gap between the strips until glue squeezed out. This method allowed us to eliminate making nail holes at each station mold.

After 8 courses of strips were glued onto both sides, we noticed that the strips were getting extremely hard to lay down at the ends because of the twist that was present

As well, we found ourselves unable to use the little clamping squares and had to resort to nails to get the strips to lie against the tight turn of the bilge.

At this time, we took a strip and bent it downward (toward the gunwales) until it fell in a fair curve without twist. We clamped it in this position at the stems and scribed a line along the top edge. Then we used my small Lie-Nielsen dovetail saw (which is actually a sweet little rip saw) to cut close to the line. Once again, we planed it down to the line with the shoulder plane. The next several strips now fell easily against the station molds without excessive twist--that is, until we got past the turn of the bilge and started stripping out the bottom.

Here is a shot of the cut we made to accommodate easier planking.

End view of our ingenious little clamping blocks.  We soon found out that they only worked where there was enough room to fit them over the previous stripping.  As we approached the keel, we had to abandon them again and go back to nailing.

Somewhere along the way, I'm not sure when, I handed Lady BK the block plane and asked her to have a go at cutting a bevel. Several minor flaws along the way had led me to a point of extreme frustration. I wanted to see if her good vision and lack of experience would trump my poor vision and skill with a block plane. All I can say is that, in the end, Lady BK did all the rest of the beveling. Didn't take long before she was doing it like a pro.  

The last several strips had quite a bit of twist in them, so much that we broke one pulling it down and had to replace it.  Some rather novel methods were needed to get these strips to lay down fair against the stems.

After several days of 4 - 6 strips per evening, we finally arrived at the point where we would begin to close the bottom of the hull. This was one of the easiest and most enjoyable parts of the stripping operation. 

First of all, the strips on the center bottom of the hull have very little twist and lie flat across the station molds. We were able to put these strips on with only a very slight bevel at certain station molds. Not only that, the strips got progressively shorter and took a lot less time to fit.

After the keel line was entirely covered with stripping, we ran a length of bright yellow Dacron fly reel backing down the exact centerline and used it to strike a perfectly straight line precisely along the keel line.  After that, I chiseled out the excess with the 2" chisel and finished with the shoulder plane.

Here is a shot of the straight run along the keel line and the space left for the closing strip.  At long last, we were ready to close the hull!

This last strip, which had to fit perfectly, took almost an hour for me to fit.

We used lengths of the green masking tape to pull the sides together in a dry run of the gluing.  When we were sure it would close properly, we put the glue on and slipped it into place on the bottom.

Here is the closing strip, all glued in.  We got plenty of glue squeeze out so we knew we had it firmly in place.

Here's a parting shot of the hull, all cleats and tape removed and lightly wet with a sponge to get an idea of what she'll look like when under varnish.

Thursday, May 22, 2008

Building A Pack Canoe - Part 3: Stripping The Tumblehome Area

The walnut strips were now ready to begin the actual stripping of the boat. The first one was placed so that its bottom edge would touch precisely at the marks on the station molds that define the upper edge of the boat (the gunwale). There were no marks for the attachment to the stems, so we bent the sheer strip up and down until we both agreed that it fell in a fair and sweet curve.

There is an old saying in boat building: "If it looks right, it is right." This pertains to the aesthetic qualities of the boat, particularly when it comes to the concept of "fairness" and "sweetness". Nowhere is this more obvious than in the lining out of the planking, and the sheer line is the most important and powerful line of all. Although we would get another chance at refining this line when we attach the gunwales, we took our time to make sure the the line was as sweet as we could get it. I'm sorry to say we totally forgot to take photos of this initial process.

We then carefully re-marked all of the lines on the station molds and stems and then clamped the sheer strip into place. I had already decided that we would not use staples to hold the strips down to the station molds. We just don't like looking at several thousand tiny black dots that tell all the world, "Hey, look... I stapled my boat together." We opted for small brads driven through cleats (so that the heads wouldn't be buried in the strips themselves) and what better tool to use than a pneumatic brad nailer.

Another decision we made was to use rolling bevels at the plank edges rather than a "bead and cove" fit. This was partially due to the fact that we were using 1/8" strips and couldn't get a set of router bits in that size, but also, we didn't see how any advantage would be gained in the complex curves. In fact, there would be a distinct disadvantage since bead and cove strips only nest together perfectly when they are 180º to each other. This only happens in the flatter sections of the hull, exactly where they aren't needed. Bead and cove fits in the harder and complex curves on the ends and the bilges always have gaps.

Here I am cutting the rolling bevel to fit the preceding strip. It is all a guesstimate with a lot of trial and error fitting by eye, but it doesn't have to be perfect. 90% of the strength of the hull will be in sandwiching the wood between two layers of fiberglass and epoxy resin, so all we really need it to do is not come apart before we glass it. It is the BK way, however, to overdo everything, so we spent a great deal of time trying to get the strips to match. This became infinitely easier as time went on.

The tumble home area is wider amidships than it is at the ends. Since the strips are all 3/4" wide to begin with, we either had to taper each one throughout the length of the strip (daunting, to say the least) or we could strip it out until the entire tumblehome area was covered and then cut down to the tumblehome edge. That is what we decided to do. It also allowed us to use up some shorter strips in the areas where the tumblehome was widest and full length strips were not needed.

Here is a good shot of the tumblehome area completely stripped and awaiting cutting down. You can see the small cleats that were used to nail the strips to the station molds and also the high-tack green 3M adhesive tape we used to pull the strips together between station molds. It is expensive, but it proved to be a powerful clamping tool and quickly became our best friend.

Also in the photo are a bunch of small but very powerful Pony spring clamps. They are being used along with short strips of 1/4" Plexiglass to align the strips in spots where the tape didn't cut it (lots of them as it turned out). After a while, we felt like a seasoned surgical team as one or the other of us would reach out a hand and say, "Plexi... clamp... more tape..."

Here is how we marked out the cut for the tumblehome edge:

First, a pencil mark was made on each station mold, exactly 1" above the place where the tumblehome and the hull sides meet.

Then, a spare strip was used as a lining batten. It was placed at each mark and temporarily nailed in place. Special care had to be exercised at the stems as there was no reference point from which to measure and so its placement had to be made by eye. There was no second chance with this one like at the sheer. Whatever line we chose had better be sweet as it would be locked in place by the succeeding basswood strips and would be more than a little bit obvious if it was a "doggy" line. When we were both satisfied, we nailed the batten to the stems.

We didn't have an offset-legged compass to make the next mark and the local art store was closed, so I went ahead and "invented" this sweet little scribing block Lady BK is using in the photo. It holds a press-fit pencil that I planed dead flat on one side. The top of the block was planed down until the flat edge of the pencil was exactly 1" from it, so it always marks out a 1" space. The pencil can be slid in and out in order to get the the top edge perfectly square to the lining batten and was a breeze to use.

Next, another batten was clamped in place right on the walnut tumblehome strips and touching each mark we had made. The batten was once again sighted for fairness and a line struck.

Here is Lady BK striking the line that we would cut to. We found that a 0.5mm HB mechanical pencil gave a crisp and sufficiently dark line to follow.

Lady BK wielding the 2" chisel to split away (carefully!) the excess walnut and pare it down to within about 1/16" of the line. The rest would be taken down with my Lie-Nielsen small shoulder plane, set extremely fine and honed razor sharp. Once again, my eye would be the final arbiter of fairness.

There was no photo of the final cut curve, but here it is with a few basswood side strips attached so you can see the taper of the curve and get an idea of what all the fuss might be about achieving the sweetest possible curve here.