“The caterpillar does all the work, but the butterfly gets all the publicity.”
I felt like a caterpillar last week. My latest project involves an oak crotch so riddled with cracks and shake that would have been better suited to the firewood pile were it not for the alluring flame figure of the grain. Just making the slab usable involved inlaying a dozen butterfly patches to stabilize the defects. Few people will look at the end result and understand the work involved, but it was enjoyable work nonetheless.
I’ve always found butterflies to be a bit tricky to make by hand. They are small and annoyingly difficult to clamp. The solution is to keep them attached to a larger block for as long as possible.
1) Mark out your cuts on a piece of wood that is quite a bit longer and wider than the butterflies that you intend to make.
2) Cut a few kerfs down to the “waist” of the butterflies. You can also cut between the butterflies, or you can wait until after the next step.
3) Using a chisel that is wider than your board, chop out the bulk of the waste, then carefully pare down to the lines, being especially careful to keep the sides of the butterfly perpendicular to its faces. Side note: Trying to cut these things using just a backsaw is a fool’s errand. You can do far more accurate work with a chisel, and it really doesn’t take any longer. Trust me, I’ve tried it both ways, and this is the way to go.
4) Now you can free the butterflies from the blank. On the opposite side, cut another kerf to the waist and remove the waste with the chisel.
5) Now your butterflies are ready to inlay. I made a variety of sizes to avoid a monotonous look. I can match the size of the butterfly to the size of the crack.
6) To inlay the butterfly, begin by locating it on the crack and carefully striking a line around it. Deepen the line with a chisel, tapping lightly with the mallet. The outlining is the most critical part of the inlaying process, so keep your focus and do it right.
7) At this stage, methods will differ. Some people like to use a router to remove the bulk of the waste. I would rather sell my first-born to cannibals than use the screaming-devil-spinny-tool when it isn’t absolutely necessary, so I opt for a cordless drill and a Forstner bit instead. I shoot for a depth somewhere between 3/8″ and 1/2″. It isn’t critical, as long as it’s consistent.
8) The remaining waste is evacuated with a few chisels. Very handy to have a bevel-edge chisel with a bevel that actually goes all the way to the edge for this task. It’s nice to get the floor as consistent as possible, but more of your focus should be on getting the walls vertical and cutting right-up-to-but-not-over the scribe lines.
9) Don’t spare the glue when you put these things in. Tap it in with a hammer, saw it flush, and level it off with a hand plane. Ahhh, that’s a nice fit. Ten more to go…