#2 , a StewMac 000-18 Slot head, is in now in the building

[Srick]

After discovering how difficult it was to clamp the braces on my first project, I decided that the next guitar would be built with a go bar deck and radius dish. The dry clamp above, when tested with my .0015 dental shim (matrix band, described in a previous post) did not disapppoint - I needed more pressure and more cauls. The glue for X brace #1 is now curing.

Visual and physical access to check the joint’s integrity with the go bar setup is much easier, as is the ability to clean up glue squeeze out. With clamps and cauls, I felt like I was flying blind. Plus, the act of tightening the clamp would often cause the brace to move off axis.

Also note, I am only gluing up the bottom x brace right now. After that cures, I can glue the second one.

[Srick]

And just now, I discovered how well this system worked.

The transverse brace moved while I was putting on the go bars. I re-positioned it and placed the rest of the bars on. The go bars make it easy to inspect the joint. Sure enough, there was a gap where the joint was glue starved. Also in that area, it was pretty clear that more pressure was needed. It was so darn easy to pop off the bars, apply more glue (fish glue with that nice long open time), and re bar the brace.

With traditional clamps, I would have likely discovered the issue after the glue had cured. The go bar deck was well worth the trouble and expense to build.

[Kevin Sjostrand]

Gobar decks are a great tool. Makes for a much easier and efficient process. Many builders will use clamps such as cam clamps for the brace gluing, and it works but the deck is a great way to do it.

[Srick]

During my first build, notching the sides (to support the bracing) drove me crazy. This time, I aced it. What changed?

• Building the guitar in an external mold gave me much more visibility than the StewMac internal form
• I did not go through the side
• I used reverse kerfing in this build, ergo, it didn’t fall apart as I was cutting it
• I taped the top to the sides (as best I could with the braces sticking out) and made sure my center lines were spot on
• I measured three times and cut once
• I’ll repeat that one: I measured three times before cutting!
• I used a small router bit to cut the notch and then finished off the braces with a fine rectangular file (HF special). Doing it this way put the two flat surfaces together

One trick that I used is to take a small bit of carbon paper (this was a specialized paper used for tracing patterns - more tear resistant) and place it in the joint - then move the top up and down in the notch. Shave off where there is a mark. Chalk marking will work too, but it's messier. FWIW, this is the same operation that a dentist performs when he\she is adjusting a filling.

[Srick]

Something was bugging me. As mentioned in another thread on the forum, I found a few voids after gluing my top. (As a back story, the top and sides had been sitting in the mold for the better part of a month until the rest of my life settled down) They were detectable by using a .001 dental matrix shim; then, while tapping the top with a rubber tipped mallet, I kept hearing a buzz, like a loose brace. I began to suspect that top was not well glued to the tail block.

Oh no…. I decided it was time for major surgery.

Since I intended this guitar to be a learning experience, I came to the conclusion it was time to learn. I had glued the top with fish glue and hit it with the heat gun. Progress was glacial.

SO I decided to use a “bigger hammer.” I started with a razor saw…



And then was able to get a deeper saw in:

[Srick]

It took about two hours to separate the top from the sides. IMO, the result was as good or better than heat removal would have achieved.

And here’s the smoking gun…


The fish glue on the tail block was still fairly glossy. It wasn’t well bonded to the top.

Most of the other areas were pretty good. Here’s a spot where the side was well glued on the edge, but not fully across the kerfing:

[Srick]

Here’s the result:


It was a successful surgery.

So what went wrong? I took great pains to make sure I had sanded a uniform 30 inch radius to the sides using a radius dish. I checked the progress of the work with chalk also.

In retrospect, I think that I needed to be more a more aggressive ‘bus driver’ - especially in the waist area. And, it appears that in a couple of areas, the braces needed a scoche more recess into the kerfing. They were close, but likely resulted in a thick glue line that gave way. In fact, this could have been the mode of failure all around - the fish glue failed because of too thick a film thickness.

Needless to say, I checked the glue up (using go bars and a halo) thoroughly before stepping away, so the thought that the glue subsequently failed because of too great a film thickness seems to hold water in my mind

Next up - lots of sanding and questing for the perfect passive fit. Then, rinse and repeat. All in all, this was an annoying detour, but better now than having the guitar fall apart on me several years from now. I hope you never have to resort to the saw.

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Postscript - a good friend, who is a nationally known luthier, has clued me in that his first twenty builds are sitting in his parent’s basement gradually falling apart. And of course, countless louths will tell you that one of the initiation rites to the profession is when you decided to take a bandsaw to your most embarrassing build.

And this is how we learn.

[Kevin Sjostrand]

Well I'm sorry you had to remove the top. However
I would guess you probably did not need to do that.

Assuming you are going to bind your guitar, once you'd cut your binding channels and glued in your binding I think you'd have found the guitar body would have been fine. When you route the channels you are effectively removing at least a third of that side to kerfing gluing surface anyway and replacing it with the glued in bindings.

Something to think about on your next one. It's not impossible to get perfectly mating surfaces here but as little off as it looks like you were, you'd probably have been fine.

But you did learn one way to remove a top so that's good.
Using Fish glue made that easier for you than if you'd used Titebond.

Keep going it will turn out just fine.

[Srick]

Kevin - thank you so much for the kind words.

I was wondering that (just as you had mentioned) whether the binding glue would have covered up the problem. But I guess I was a glutton for punishment. Those small gaps bothered me - I’ll bet I’m not the only one who has them in their builds. Regardless, I learned from this. Perhaps the biggest thing that I learned is that with patience and the right tools, there’s very little that can’t be fixed. And besides, how often do we get to do a forensic evaluation of our work?

Fun, fun, fun!

[Srick]

Oh, those darn binding channels.

It’s no accident that folks have come up with dozens of ways to cut them. Anytime you see dozens of ways to achieve the same goal, it likely means that it’s not going to be easy. So,I was pretty sure that I had really screwed mine up. They were sloped, they were uneven, they sucked.

And then, I discovered this post:

viewtopic.php?f=48&t=10006&p=59565&hilit=Iwasaki#p59565

Diane describes two files, an Iwasaki razor file and a Corradi riffler file, both available from Woodcraft. These two files performed miracles! They were worth every penny. Thank you Diane!