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PostPosted: Wed Mar 18, 2009 1:20 pm 
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First name: Martin
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I'm a first-time builder, working on a 000 kit.

I have a problem and I'm not sure how to fix it. I've been consumed with this problem. friends of mine are bumping into to me today, and asking, "dude, what's wrong?!"

I glued the back to my rim a few nights ago. When I did it, I used this method (http://www.kennethmichaelguitars.com/attachback.html), with rubber bands attached to screws on the mold. After putting all the rubber bands on, I noticed that the edge of my top was touching a piece of wood on my mold, and was creating a small crack. but luckily, it's an edge that will be trimmed off when I do the flush-cut with the router. still, at the time, I was intensely worried about the crack, so I hurriedly took off all the rubber bands, unscrewed all the clamps, and quickly put it all back together, and let it sit for the night.

In my haste, I hadn't noticed that the very edge of my spruce center strip was sitting just underneath the neck block, a tiny bit. now everything is dry, and I don't know what to do. I'm thinking I can get something like one of those dental tools that looks like a hook, and pick out the wood from underneath the neck block. it would look ugly, but it might fix most of my problem.

Or, I could use a chisel with a shortened handle, and dig out that piece of spruce by working thru the soundhole, and glue in another section?

any ideas? thanks in advance.


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PostPosted: Wed Mar 18, 2009 1:38 pm 
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Martin,

Welcome to the OLF.

It sounds to me like the reinforcing strip is holding the back away from the neck block. This part of the neck block plays a large part in preventing the tension from strings from rotating the neck and neck block so that eventually (or sooner) the fretboard extendsion will dive into the inside of the body, making the string action high.

Too bad, but the only solution as I see it is to remove the back, remove the old glue, and reglue the back. Some of us use pins or other locating aids to be sure the back (or top) stay properly positioned while gluing.

Pat

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PostPosted: Wed Mar 18, 2009 1:45 pm 
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Pat Foster wrote:
It sounds to me like the reinforcing strip is holding the back away from the neck block.
hi Pat,
you're right, that's exactly what's happening.

since it's just a sliver (1/32nd?) holding up the neck block, would removing the back be too drastic a step? since the strip is the problem, I was thinking I would just remove the strip.

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PostPosted: Wed Mar 18, 2009 1:58 pm 
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Martin,

The problem with the joint now is that any glue that is under the neck block has set, so even if you chisel out the piece of the strip that's holding the back away from the neck block and stuff glue in and clamp it, the old glue will be in the way and prevent the two surfaces from making good contact. What you need at this joint is a thin glue line between the two pieces, such that a minimum amount of glue is in the joint. The glue itself has little strength.

Consider this experience part of your initiation.

Pat

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PostPosted: Wed Mar 18, 2009 2:00 pm 
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Sure, try removing the offending strip and then try to get the top glued down securely to the rim and blocks. Use a household iron to heat the wood and soften the glue allowing the plate to make good contact. If this fails, then you can remove the entire top.


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PostPosted: Wed Mar 18, 2009 5:45 pm 
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I've decided the only way to go is to remove the back. I plan to use a household iron. wish me luck.

Image

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PostPosted: Wed Mar 18, 2009 8:11 pm 
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Good decision. It would work for awhile the way it is, but you'd have felt even worse later, when it came apart after the binding and finsish were done.

Use a clothes iron, on pretty low heat. If you're using one of the common white glues, like LMI or Titebond I (maybe they call it original), you don't need to get much above about 130°F. Use a pallet knife from an art store, or a thin-blade butter knife, with a dull but smooth edge. Heat the edge of the back a bit, work the knife in, not prying, being careful not to gouge the wood. Take it a little at a time. Heating the knife blade a little as you go will help too. Don't rush. Leave the tail and neck blocks 'til last, when you've gotten a feel for it, and take extra care at the blocks so as not to compromise the backstrip joint. Let us know how it goes.

Pat

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PostPosted: Wed Mar 18, 2009 8:21 pm 
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Hey, Martin, I see you found your way over!

Sadly, I think the best thing you can do is go ahead and remove the back like you were saying. That's a pretty critical joint and you can bet there is little to no contact underneath it.

Don't sweat it though, man! We all know how frustrating it can be, but that's just all part of it. You'd much rather fix it at this point than wait until later to find out you've got a real problem. Granted, you "could" finish it and "maybe" never have a problem with it - but just make some lemonade out of this and look at the valuable repair experience you'll be getting. That's gotten to be my philospohy these days, and Lord knows you get enough opportunity to learn to make repairs on even your own screw-ups in this trade/hobby/pastime.

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PostPosted: Wed Mar 18, 2009 11:14 pm 
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Yes, thanks, Wes!

I used my pocket knife because it has a very thin blade...

Image

I let the heat do the work. and about an hour later the back was off. no problems.

Image

After further inspecting the guitar, I'm really glad I removed the back. I believe that when I trimmed my neck block, that I made it too short. I shouldn't have trimmed it at all -- just sanded it. So I've glued a piece of maple to the bottom of it, 1/8th" thick. I'll sand it tomorrow night with my radiused sanding bar to match the contours of the sides.

Image

It was true that the block was resting on top of the center strip, but the bottom of my neck block wouldn't have touched the inside of the back anyway. I'm making all kinds of beginner mistakes on this thing. I need to be more careful.

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PostPosted: Thu Mar 19, 2009 12:21 pm 
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Great. I suspect when you're done with this project, you'll be glad you took this route.

One little thing. In the future, not that this will happen again ;) heating the back itself might be a better method, rather than the sides as in your photo. The back/lining joint is closer to the back than to the sides.

Congratulations!

Pat

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PostPosted: Thu Mar 19, 2009 1:15 pm 
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Pat Foster wrote:
One little thing. In the future, not that this will happen again ;) heating the back itself might be a better method, rather than the sides as in your photo. The back/lining joint is closer to the back than to the sides.


Thanks for all your help. The thing that made me want to take the dive was your comment about the "initiation!"

When I started working on it, I heated the back. The iron darkened the wood. not having done this before, I wasn't sure how easy it would come off, or if putting a t-shirt or something between the iron and the wood would do it ... or whatever ... so I just went for the side and it worked too. I figured it probably took longer, but it worked out ok, and most of the marks it made will be routed off.

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