Butterflies

The big elm yoke blank should be dry.  John Sarge stored it inside at least a couple of years, then it sat in Tillers' shop for a year, then it sat in my outdoor shop for a few months.  Once the rough shaping was done, I brought it into my basement shop.  Then it happened.

A check.  Not deep, but long.  All across the belly and spanning the neck seat on one side.  Maybe it won't get worse, but there's a lot of work in a blank that big, so fixing it now seemed the better course.

John Sarge jokes that one of Tillers' yokes has been repaired so often that there is more Bondo than yoke in it now, but automotive dent filler is not really in my wheelhouse.  I'm a woodworker, so WWWD:  What would a woodworker do? 

Butterfly keys.

Shaped like an opposing pair of dovetails, the keys hold a check or a split together.  The particulars of shape and angle aren't critical, so long as the butterfly is cut along the grain and then placed across the grain of the split. 

I started with a 2 1/2" length of cherry and cut out a key with a handsaw.  I debated walking out to the shop to use the bandsaw for the cut.  I'm glad I didn't.  A dovetail cut is a dovetail cut.  (see photo) Then I smoothed the edges
with a chisel while creating a very slight bevel.  Think of the butterfly like a cork in a wine bottle and you get the idea. 

The next step was to lay the key across the split and trace it carefully.  I bored a few 5/8" holes in the "hole" area of the key to remove most of the material from the hole, then chiseled up to the lines I had traced.  Finally, I used a router plane to (mostly) flatten the bottom of the hole to a consistent depth.  The small recesses where the lead screw of the drill bit left a mark? I left those to give excess glue a place to go.

For glue, I chose a 2-part epoxy.  The combination of strength and the ability of epoxy to fill in gaps made it a logical choice.  I most often use hide glue for woodworking, but it's not water-or-heat resistant.  And the waterproof woodworking glues only bond on surface-to-surface contact.  My "cork" bevel would result in a tight fit at the surface, but would leave the possibility of a slight gap below.

After mixing and spreading the epoxy, a hammer and a

block of wood drove in the key. 24 hours later, I planed off the part of the key that was proud of the hole and used a scraper to level the surface.

It looks pretty good. 

Does it work?

I'll let you know in a few years.  

Update:  click here to see if it worked. . .