Gap in Drop Top

[John Cavanaugh]

I'm faced with another learning experience.

I'm building a Telecaster-like electric guitar with a hollowed-out walnut body and a curly maple drop top. I glued the top to the body yesterday and when I took it out of the go-bar deck, I noticed that I have a big gap between the body and top along the outside of the cutaway horn:

IMG_0086.JPG

The gap is about 3/64" wide, almost 4" long, and about 3/8" deep. I am planning to bind the top of the guitar.

My thoughts about addressing this are, in order of best to worst:

• Fill the gap with epoxy, sand the horn flat, and let the binding cover the gap,
  Heat up the top over the horn to soften the glue, then clamp it down. I glued it with Titebond. Would this even work?
  Take the top off, clean it up, and glue it on again. I really don't want to do this.

What are your thoughts? Is one of my ideas reasonable, or is there something else I should consider?

Thanks.

[Dennis Leahy]

John,

I'd try your #2 idea first (heat it up and try to clamp it down), and if still unacceptable, then try #1. Even if just your #1 idea is used alone, you'll only be losing 3/64" out of about 5/64" thick top so it should work without sanding through the top. I'd still try to reduce the gap first, just to be 100% sure there is no top-destroying sand-through.

[coopman]

John - I am more or less in agreement with Dennis's recommendations. However one caution: clamping that gap shut after heating may introduce more tension on the joint, causing a possible future "delamination" if the glue joint is not optimal and the maple wants to go back to straight. Did it fit snugly in your original test fit and was just mis-clamped or was it not a great fit to start ? I would try to get some fresh glue in the joint somehow, if you are going with option #2.

I am slowly learning myself, that well executed joints require very minimal clamping pressure. Keep us posted!

John

ps - the binding should be able to add a good amount of holding power to the seam ... kind of like kerfing on the outside

[Eben]

In addition to the above, before you leap, I got questions -

Was all this wood hanging in the same environment before you glued it up?
Any major changes in weather while this happened?
Anything else on the drop top deflected/acting weird?

If this thing is stable, I would not opt for #2. Forcing something into a glue joint is never a best bet. It should fit snugly without all that, and if it doesn't, then it's time to figure out exactly why, and fix that, eh?

I'd get some sanding dust from the main body worked up, and fill the gap with a slurry of glue and dust, and let 'er rip.

This is not gospel, just M2CW - without knowing what caused that to happen, I lean towards charitable caution.

E

[John Cavanaugh]

Thanks, everyone, for the replies. To answer the questions that have been asked:

Did it fit snugly in your original test fit and was just mis-clamped or was it not a great fit to start ?

I thought it fit when I tried it, but it may well be that I wasn't careful enough. I clamped it in my go-bar deck and it may be that the go bars didn't produce enough pressure to smooth out a warp in the top.

Was all this wood hanging in the same environment before you glued it up?
Any major changes in weather while this happened?
Anything else on the drop top deflected/acting weird?

The wood has all been in the same environment for a couple of years. There were no changes in the weather (to the extent that you can ever say that in Minnesota). The rest of the top looks fine.

I have an experiment in progress to test the heat-it-up-and-clamp-it approach, but my attention has been pulled away by repairs to my garage. I'll let you know how it turns out.

[John Cavanaugh]

I was wondering how Titebond would react to being heated, clamped up, and cooled, so I did an experiment. I took a scrap of maple and a scrap of walnut, coated them both with Titebond, and glued them together with a piece of UHMW propping them apart at one end.

IMG_0087.JPG

I let it sit for a couple of days, then took the UHMW out and applied heat from my high-tech heating device (a clothes iron). For purposes of illustration, I took this photo with the iron off to the side so you can see the wood that I'm heating up.

IMG_0088.JPG

Once the glue was soft, I clamped the two pieces together.

IMG_0089.JPG

I let them cool, then tried to split them apart with a wood chisel. The part of the joint that was held open came apart at the glue line, but at the other end, the wood split.

IMG_0090.JPG

My conclusion is that a Titebond joint that is heated and cooled will still be strong, but I wouldn't count on heat to close up a big gap.

So I went with my original idea and filled the gap with epoxy. I'll need to sand the top down a little, but not much, and the binding will cover the gap. My thanks to everyone who gave me advice.

[coopman]

John - excellent idea for testing. Thanks for sharing the results with us. We'll look forward to seeing more of this build.
-John