Gibson SJ brace

[Ian Davlin The Looth Group]

You do see that from time to time. It isn’t great, but probably not the end of the world. If I was being cautious, I would glue it up and then cap over the top of the X with some ebony.

[Michael Minton]

A gap like that will happen if the notches for the x-brace aren’t cut perfectly. I don’t think filling the gap would do anything helpful, but it does suggest the x-brace isn’t going to be as stiff as it should be. And that X is probably the most important load bearing point on the top. Ervin Somogy (and several other great builders) convinced me of the importance of putting a 1.5 to 2 mm patch over the halves where the notching has interrupted the joint (across the open notches). See Somogyi “Making the Responsive Guitar” p. 43. Make the patch the width of the x brace, about 20 mm long, and taper down the ends.

[Mike Hoenerhoff Elderly Instruments]

I don’t have a catalog of examples, but it seems that I’ve seen more drastic Gibson x-brace failures when the braces aren’t fit well together. I have a 60’s hummingbird in right now where the one side has completely separated across the grain right at the join where the x comes together. There’s a pretty significant gap on this one. I think that gap allows for extra movement in that joint and makes catastrophic failure more likely.