Thinned and braced top of a small body guitar

[Henning]

Originally Posted by Fathand

Since you are changing to X brace, are you going to be using steel strings and a pin bridge?

Yes, that is the purpose of the conversion to X-brace. Do you please have any idea about the bracing I've made?
Supposedly it would not make such a big difference to lower to the height of the X-crossing from 15 to say 12,5 mm, would it?
Or something else I could do?
I intend to go for XL or XXL strings.
Regards

[Fathand]

Originally Posted by Henning

Yes, that is the purpose of the conversion to X-brace. Do you please have any idea about the bracing I've made?
Supposedly it would not make such a big difference to lower to the height of the X-crossing from 15 to say 12,5 mm, would it?
Or something else I could do?
I intend to go for XL or XXL strings.
Regards

The bracing looks ok to me. Smaller bracing might work with XL strings but what if you're not happy with those?
You could just copy bracing profiles from an existing small body guitar plan.
There is a free 00 plan to download here;


https://www.grellier.fr/en/downloads

[RJVB]

Originally Posted by Fathand

Since you are changing to X brace, are you going to be using steel strings and a pin bridge?

FWIW, both designs originated on gut-strung guitars, in Europe! (X-bracing admittedly at about the same time that Martin was experimenting with steel strings in the US.)

[Fathand]

Originally Posted by RJVB

FWIW, both designs originated on gut-strung guitars, in Europe! (X-bracing admittedly at about the same time that Martin was experimenting with steel strings in the US.)

The first Martin X braced guitar similar to today's X bracing was in the early 1840s, with gut strings. Look up the Madame De Goni guitar. Steel strings didn't enter the market til around 1900.

[Henning]

I've been looking at the Grellier plans, (God knows I have!), my digital screen Grellier plan is worn out. But those are for a slightly bigger instrument, as far as I can see, aren't they. Or, what is important here, the scale length.
Yes, there must have been quite a long era where X-braced guitars were sold with gut strings. For at least some +50-years. Here is the Madame de Goni guitar

[redir]

Originally Posted by Henning

Yes, that is the purpose of the conversion to X-brace. Do you please have any idea about the bracing I've made?
Supposedly it would not make such a big difference to lower to the height of the X-crossing from 15 to say 12,5 mm, would it?
Or something else I could do?
I intend to go for XL or XXL strings.
Regards

You definitely want to have a lot of strength there I would suggest you leave it as is.

The only thing I might suggest for your bracing, though it's hard to tell from pics, is that the 'node' of the scalloped braces on the interior of the guitar are typically taller then the nodes at the end of the braces. It sort of looks from the pics that your two peaks are equal height. I would have kept the upper X-Brace ends in the upper bought a bit thicker too but it's too late for that and it's probably fine as is.

I think you are good to go though.

One thing I am curious about, why didn't you fix the top crack first before bracing the guitar? It probably doesn't matter either way but the way I think about things, that's what I would have done first.

[Henning]

Thank you redir, I tried to fix the top crack, but then it cracked again. I simply couldn't push it together. There were too much tensions introduced in it.

[Bruce Sexauer]

Splinter fill.

[Henning]

Originally Posted by Bruce Sexauer

Splinter fill.

Yeah, that's exactly what i've done. Supposedly i'll need some strengthening above the upper transverse bar too, to stop the neck from digging into the top. However there is a problem that i am staggering with now. Since time has passed from when i took it apart, the back and sides part have changed shape. So the top doesn't fit anymore.

[Fathand]

Originally Posted by Henning

I've been looking at the Grellier plans, (God knows I have!), my digital screen Grellier plan is worn out. But those are for a slightly bigger instrument, as far as I can see, aren't they. Or, what is important here, the scale length.]

I have built size1 and size 2 (14 fret) guitars both with steel strings. Your guitar seems to fit in between those sizes. I used 1/4" x 9/16" tall main bracing on both. Or 6.35x14.3mm. The size 2 at 12 1/4" /31.2 mm wide has a top similar thickness to yours and med light 12-54 strings. Both 629mm scale. Similar bracing pattern on both with 1 finger joint per side and 1 tone bar.

Both of these guitars are very responsive and have very nice tone. Neither have showed any sign of bellying.

I would leave what you have, as is. Don't overthink it. No one can tell you the perfect bracing dimensions because it is subjective to the players taste, playing style and the particular pieces of wood, etc.

What are you doing about the bridge? I had a similar guitar around 1969 with similar bridge and steel strings. It flew off one day. If that were my guitar, I would install a pyramid or similar straight pin bridge.

You have cracks on both(?) sides of you fret board extension. Will you be beefing up the neck block and or adding a popsicle brace?

[Henning]

As you can see, i've made quite a big transverse bar. I'll add a layer of spruce veneer to that. I'll have to make a complete new bridge. That way it can cover the old bridge on the top. I got some rosewood for that. The old bridge was dragged skewed. Yes, a pin bridge. It would be a good idea to set in a block under the fingerboard tight to the top. One problem is that the neck heel block is made of, not exactly the best quality of spruce.
As i dont have that advanced tools, i will find problems with setting the body to be level to the top edge. I might have to give that part of the restoration away, unfortunately.

[redir]

Originally Posted by Henning

Yeah, that's exactly what i've done. Supposedly i'll need some strengthening above the upper transverse bar too, to stop the neck from digging into the top. However there is a problem that i am staggering with now. Since time has passed from when i took it apart, the back and sides part have changed shape. So the top doesn't fit anymore.

Restoration can be difficult work. Sounds like you are learning a ton from doing it though which is good. If I have to dissemble a sound box I will make a simple outside cardboard mold to hold the box in shape while working on the top. Sometimes you don't need it, other times you are glad you did it. You might still be able to make a mold based on your top and then force the sides into place.

Pic for example. I had to remove the back of this old Gibson L-48.

[Fathand]

Originally Posted by Henning

. It would be a good idea to set in a block under the fingerboard tight to the top. One problem is that the neck heel block is made of, not exactly the best quality of spruce.

As i dont have that advanced tools, i will find problems with setting the body to be level to the top edge. I might have to give that part of the restoration away, unfortunately.

Is your top now radiused with the new bracing? If so, a sanding stick of the same radius can help marry the top to the back. If flat, then sand edges flat.

https://www.flickr.com/photos/194462...7720296630125/

Gluing the top on while in a mold is a good idea.

https://www.flickr.com/photos/194462...7720296630125/

Spreaders inside the guitar during gluing can help, make sure the will come out through the sound hole

https://www.flickr.com/photos/194462...7720296630125/

You could add something stable like Mahogany, Khaya or even Baltic Birch plywood to extend your neck block , strengthen it and provide more support under the fretboard extension. See the neckblock in above pic.

[Henning]

Thank you so much, these are tremendous ideas. I had already glued a block of spruce to neck block to straighten it. I will consider this and try to find some cardboard too.
I just made a small arch to the top. This was one of the main reasons for changing the bracing. It now seems to be fine and concave. Before it was convex. Thank you for reminding me to make the surface of the back and side to mate to the top. I don't know right now how to improvise the spreaders inside, that can be taken out of the sound hole easily. I've planned for making a block under the fret board extension.

[Fathand]

Originally Posted by Henning

Thank you so much, these are tremendous ideas. I had already glued a block of spruce to neck block to straighten it. I will consider this and try to find some cardboard too.
I just made a small arch to the top. This was one of the main reasons for changing the bracing. It now seems to be fine and concave. Before it was convex. Thank you for reminding me to make the surface of the back and side to mate to the top. I don't know right now how to improvise the spreaders inside, that can be taken out of the sound hole easily. I've planned for making a block under the fret board extension.

I built a flat top mandolin. The top looked concave after the strings went on. I removed the top and added a curved brace to radius the top. My top outline was now smaller than the body. I solved by adding binding. You may find similar issues?

My spreaders are made of scrap plywood blocks and are held apart by 5/16" threaded rod with a nut on one end and a wing nut on the other. I reach through the sound hole and take them apart but check that they fit through before gluing top on.

https://www.flickr.com/photos/194462...7720296629122/