Good morning folks!
Remembering the background of the wood and the possibility of defects, I tried to place the planks in a way which would put cracks outside the usable arc. For the most part it worked out, except for the two shown. The chestnut (right) crack was a combination of a nail hole, crack, and two squirely knots; I knew that it would eventually get bigger and possibly split the panel right in half. The oak crack wasn’t as pronounced and was mostly outside the arc, but there was going to be a bit left in the circle so I thought I would prevent any further separation.
I had two options: epoxy or bow tie keys. I don’t have any epoxy and to do it right I would have to tint the adhesive to match the wood or to pitch black, plus to get enough epoxy it would be rather expensive. That leaves bow tie keys! I explained in another on going series Project of Brotherly Love that anything worth practicing is worth putting into a project. Inlaying is a technique I had yet to attempt, mostly since you often need special tools or a router; I have a router but have very little experience with it and to be honest the damn thing is freighting.
The bow tie key works by running long grain perpendicular or at least more than 45 degrees to the work piece’s long grain. Wood only expands along its width (pulling the grain apart) but not with its grain so as the work pieces expands along its width, the crack widens. With the bow tie key inlayed at least half the thickness of the work piece and it’s grain going opposite the two grains counter act each other. The panel wants to expand but the key won’t let it.
The process began with first cutting the keys; I had quite a few scraps from the
dimensioning process. I took a piece of chestnut and resawed it roughly in half and quickly planed one face flat then used by dovetail marker to trace out the angles of the key. The size and angle are completely arbitrary and are more of a design decision; as long as the angle isn’t severe (no more than 50 degrees would be a safe bet). Using my dovetail saw I cut out the key doing my best to keep the kerf plum with the board; if the edge isn’t square then the tightness of the key would be in question.
Making the keys did not require much precision but the mortises need to precisely match the key to provide the greatest strength. To best ensure the best fit I placed double stick tape on the flat face of the key and stuck them to the panel with the middle of the key straddling the crack on either side. I then used the marking knife to slice the grain along the edges of the key making a great “chalk outline” of the key. With the knife line, place a chisel (I used a large chisel to match the length of the dovetail) and push in a larger/deeper knife line. Using the same chisel I then square the back with the knife line and tap half strength to deepen the line and coming back with the chisel to pair out a deeper groove. I continue this process until I am about 1/4 – 3/8 deep; the panel is 13/16 thick so a little less than half is more than enough meat for the key to be most effective. The knife line process leaves the middle still high and uneven which needs to be taken down to level. One can do this by using a chisel with the bevel down to prevent going too deep. But I have a Stanley No. 9 router plane and always try to find a place to use it. The router plane lowers a horizontal blade below a flat base which registers along the face of the panel; by lowering the blade in 1/32 increments I am able to quickly remove material and ensure the bottom of the mortise. Unfortunately with the keys being as tight as possible and thickness matching the mortise depth as close as possible, dry fits weren’t an option. Biting the bullet I slathered glue in the mortise and the flat face of the keys and hammered them in using a scrap block and mallet. I had some solid glue squeeze out letting me know the joint was tight. Once the glue cured I flushed the keys with the panel using a block plane and they were finally done. The process took about 30 minutes for both keys, well worth my time.
Thank you following along with the build. Stay tuned for more projects from the PlaneOleWoodShop. If you have any questions or advice for myself or other viewers please feel free to leave a comment below.