Box assembly Question

[Diane Kauffmds]

As I'm starting to build guitar #2, it occurred to me that most of us construct the box by gluing the back on the sides first.

Is there a reason for doing this? Why not attach the top first?

The top is at least 75%, if not more, of the voice of the guitar. Since the bracing is more complex, wouldn't it be more prudent to put the top on first? By doing this, we can really see the placement of the braces through the kerfing, make sure that the top is centered easier, plus shave any problematic braces, before the box is closed.

Is it okay to do this, or will I run into problems?

[B. Howard]

I always attach my top to the rims first. I think most people do the back first as it can be seen through the soundhole and allows them to clean up the glue.

[Diane Kauffmds]

Thank you Brian. I wanted to make sure it was an acceptable way of assembly. It makes total sense to me.

[MaineGeezer]

Looking back through my project blog....I glued the back on first. Why? Because that's what Carter said to do. I'm sure he has a reason for doing the back first. I'll ask.

[Ben-Had]

I'm on like #30 and have never done the back first. Personal choice.

[ruby@magpage.com]

I have built 5 and done both - I see no difference except the visual on the back to side joint through the sound hole. But I find that Titebond does not look bad enough that I want to remove the residue.

Ed

[tippie53]

I have made over 200 and do the back first so as you see it is 100% choice. I do like that I can clean the back of any visible glue that is the only reason.

[Ben-Had]

I would say the best reason to do the back first is to clean out glue residue you may see and to do the top first if you want a final chance to tune the braces one more time before closing it up. Also, I don't use a popsicle brace on my guitars. I use one that is custom fit between the neck block and UTB and that can only be done with the top going on first.

For anyone that is interested:

You can glue a small patch in place of the popsicle. The main reason for either one is to prevent top cracks next to the fingerboard. Unless the guitar has a soundhole that is smaller than the width of the fingerboard, the need for reinforcement is the same, regardless of the size of the guitar.
My small patch is about .1 to .125" thick. It is quartersawn. The grain is parallel with the grain in the top. It is sized to fit tightly between the neck block and the UTB (very important to prevent neck block shift). The width is the same as the neck block where it contacts it, flaring to the width of the soundhole where it contacts the UTB. That forms the trapezoidal shape. The angled edges prevent a stress riser which would occur when the edges of the patch are parallel with the grain in the top. A cross-grain patch has two disadvantages. In the case of a Martin, it is 1" wide. Gross-grain construction that is that wide will tend to loosen over time, due to differential shrinkage. That is why popsicle braces often don't prevent the top crack beside the fingerboard. The second disadvantage is that it will not guard against neck block shift, since wood is not nearly as stiff or as stable across the grain. In other words, any shrinkage will cause a gap to form between the patch and the block or the UTB, defeating the purpose.

[watergunn]

I do the back first so I can clean the glue and also to glue in the center strip that touches the neck block and the tail block.

Rick Gunn

[Diane Kauffmds]

I would say the best reason to do the back first is to clean out glue residue you may see and to do the top first if you want a final chance to tune the braces one more time before closing it up. Also, I don't use a popsicle brace on my guitars. I use one that is custom fit between the neck block and UTB and that can only be done with the top going on first.

For anyone that is interested:

You can glue a small patch in place of the popsicle. The main reason for either one is to prevent top cracks next to the fingerboard. Unless the guitar has a soundhole that is smaller than the width of the fingerboard, the need for reinforcement is the same, regardless of the size of the guitar.
My small patch is about .1 to .125" thick. It is quartersawn. The grain is parallel with the grain in the top. It is sized to fit tightly between the neck block and the UTB (very important to prevent neck block shift). The width is the same as the neck block where it contacts it, flaring to the width of the soundhole where it contacts the UTB. That forms the trapezoidal shape. The angled edges prevent a stress riser which would occur when the edges of the patch are parallel with the grain in the top. A cross-grain patch has two disadvantages. In the case of a Martin, it is 1" wide. Gross-grain construction that is that wide will tend to loosen over time, due to differential shrinkage. That is why popsicle braces often don't prevent the top crack beside the fingerboard. The second disadvantage is that it will not guard against neck block shift, since wood is not nearly as stiff or as stable across the grain. In other words, any shrinkage will cause a gap to form between the patch and the block or the UTB, defeating the purpose.

I'm so glad that you made this post. I plan to use a brace like this instead of the popsicle. Your post gave me a visual reference for the brace.

Thanks to everyone who has responded.