Back Crack Repair on the Vintage Martin Ukulele

Now I start in on the back crack repair.  I'm going to glue the crack itself, then glue the split brace, and then make up and attach two spruce cleats along the crack inside the body.

First I clean up the crack as best I can.  I opened up the crack by pushing it gently from the outside and used compressed air to get any loose dirt out.  Then I used my Mighty Mite vacuum to get anything else out.

In looking at the crack, I think it's not a typical humidity-related crack.  It doesn't follow the grain of the wood exactly, which is what most cracks do.  And I can only open it by pushing from the outside.  I suspect it was dropped, or something dropped onto it.  There is some of the top surface of the wood that's missing along the crack, which also makes me suspect it was done by a hit.  My original thought that it started small may be true - it could have been a 'normal' crack, then it got hit and the crack lengthened. 

 Spread glue along the crack, opened it up and worked it into the crack.  Then I wiped the excess off with a clean damp rag.

How beautiful is that finish?  I can't wait to clean it up some.  

Used three different techniques at once to help close it up.  I discovered that it was slightly opened on its own, and that pressure on the sides would close it up some.  So I put a bar clamp on the upper bout to help close it.

Then I used the usual stretchy masking tape over the rest of the crack to pull it closed.  And finally, to make sure it stayed level on the longest (and most open) end, I used magnets and acrylic cauls to hold it down.

There was glue squeeze-out on the inside and outside as I clamped it - again I used the damp cloth to clean most of it up.