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Guitar Build – oops, what to do with a mistake?

Posted by is9582 on October 28, 2012 with No Commentsas , , , , , , ,

Well, I know this guitar has been sitting around in pieces for way too long. I’m doing lots better with my back recovery, so I’m doing my best to get after this Les Paul and finish it before long. Yeah, famous last words, huh?

I got out in the shop early this week and thought I’d do some work on the guitar. Before I started something new, I figured I’d refresh myself with what I’d done so far. (Yep, it’s been that long.) I dry fitted the neck in the guitar body. Looked ok.  I wanted to see what the fingerboard looked like in it’s final position. After placing the fingerboard, I stepped back and saw something I didn’t like. I reached over to the guitar and sure enough, the fingerboard was actually hanging over into the cutout area. I couldn’t believe what I was seeing. The portion of the cutout area, that is next to the fingerboard, was curved a bit more than needed. The front section of the cutout should end up parallel to the guitar centerline. Mine was angling away from the centerline, at the very front section.

The blue arrow is pointing out the wood that is to the left of the line, which is the problem.

 I’m sure I checked it before, but for whatever reason, I didn’t notice the problem before. Now all of the crazy thoughts started running through my mind. How did this happen? What can I do to fix it? Is this build toast??

After thinking about it for a few minutes, I knew what I was going to do. I would measure how much material was in excess in the cutout area, and then transfer that distance to the oposite side of the neck mortise.

Setting distance.
Marking wood for removal.

Afterwards, I would use the same measurement to make a patch to glue into the mortise, for the side where the error was closest. Then I’d remove the same amount of wood on the other side of the mortise. This would shift the neck away from the cutout, and still provide a nice firm fit for the neck in the body.

I initially cut a piece of Mahogany, that would be my patch, a little bit thick so I could sneak up on the fit I wanted.

Terrible picture, but hopefully you can tell it is a thin patch.

After making sure the patch was a good fit, on everything but it’s thickness, I started removing the wood from the other side of the neck mortise. I began this process with some sharp chisels, and taking my time, gradually worked back towards my line. When I was about 1/16″ away, I stopped, as I wanted to finish it up with my router. This way I’d know for sure the side was completely perpendicular to the top surface. This would match my guitar neck’s tenon. I re-used the MDF template I originally made to fit the neck to the guitar. This time, however, I was only concerned with one side of the template, as well as the cross piece, lining up with my lines. I used double-sided carpet tape to adhere the template to the body. I also needed to place two wedges under the end of the template, since the front of the guitar body is already shaped on the front section, angling down towards the neck. If I didn’t use the wedges, the back section would be floating, and the template might move. I took two light passes and was done with that portion of the fix. I tested the fit of my guitar’s neck, into the mortise, and it was too tight. Perfect! This is what I’d planned for, and if it was too loose, I’d just make another patch. This is also why I didn’t glue the patch in place, before routing the fix in the other side. I took the patch to my workbench and with one of my small block planes, took a couple shavings. I went back to the guitar and tested the fit. It was still too tight. After going back and forth a number of times, I noticed I was getting close, as the neck’s tenon started going in at the front of the opening, but was still too tight at the other areas. With this info, I started marking on the patch with a pencil, so I would only remove wood from the needed areas. After some further work, I nailed the perfect fit. This is where hand planes really show their stuff. I can’t even imagine trying to do this type of precision work on the table saw, using chisels, the band saw, or even any form of sanding.

After having the neck dry fit into the body, again, I checked that the fingerboard was no longer hanging over the cutout. Exactly where I wanted it. So, I glued the patch into the neck mortise, using basic yellow glue. Make sure to clamp it up and let it sit. I decided to leave it overnight, even though it wasn’t necessary to have clamps on it that long.

The blue arrow is drawing attention to the new patch. You can also see the small beads of glue that squeezed out when clamped. 

I took a couple of pictures after the glue had set, with the neck dry fit into the new opening, and also with the fingerboard in place. You can see how the fingerboard is just on the other side of the line by the cutout.

Left arrow is pointing to the new patch, and the right arrow is showing the nice fit.
With the fingerboard laid in place, the arrow is pointing to the excess wood in the cutout.

I still have some work to do, before gluing the neck into the body, but hopefully it won’t be too long before that and other aspects of this build are complete. I just have to be careful with each process, making sure I don’t inadvertently cause myself extra work. 😉 Just remember to have fun with whatever you’re making. Even this little oops, was a good learning experience in the guitar building world. One more thing I know, not to do.