Table Top Crack? Butterfly Key Solution

What to do when your live edge table has a large crack.

We love our wooden slabs with their gorgeous grain and natural edges.  We embrace their natural defects for they tell the story of the tree’s life.  However, large splits can make big slabs unstable. Consider a contemporary butterfly or dovetail keys, made popular in the 1950s by George Nakashima, a Japanese-America woodworker.

While the inlay process is simple in concept, it can be tricky in practice.  Some people use a template and router but not me.  I do it the old fashion way.  It allows me to shape or size the key to suite the job at hand.  For the Viking table I wanted one large 6” key to bridge the largest gap at the end of the slab.    This handmade touch is now both decorative and structural. 

Side Taper is the Secret.
Stealing a page from the master, I add a slight bevel to the sides of my keys—roughly 1 degree or so, depending on the hardness of the woods—which makes the inlay process more forgiving. Stray a little with your knife or chisel, and the key fills the gaps as you drive it into place. The wood in the slab compresses a little to accommodate the slightly over-sized key.

To add that bevel in a consistent way I used a bandsaw to cut out the key with a 1° angle on all six sides, ripped it to about 2.5” thick and then used my disc sander to fine tune all sides.  There are several youtube videos to give you ideas on how to do this with the tools you have.

For wood selection I decided to go with leftover oak burl from a bowl I turned.  As the slab does not have too much variation in colors I did not want the key to dominate the table’s look by being too much of a contrast.  Selecting a piece of burl provides subtle interest.  It is also a much harder wood and the pecan gave way as I drove the key in, not the key itself. 

The rest of the process is pretty typical for all types of inlay: you rout to establish the depth of the pocket, and clean all sides with chisels.  After checking my work a few dozen times I am ready to glue the mortise walls and drive the key evenly in place.  A bit of sanding while the glue is still wet creates a mixture of glue and sawdust that will fill any defects and I am done, after 3 hours work. No need to use epoxy to fill defects.  Wood moves and it will eventually pop out this small amount of epoxy.