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Body depth problem from a new member
http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=26104		 Page 1 of 1
Author:  rmcctr [ Wed Feb 17, 2010 11:36 am ]
Post subject:  Body depth problem from a new member
Hello everyone,
I am a new guitar builder from Greece and i am now building my first acoustic guitar.
Unfortunatelly i made a terrible mistake with my sides.
One of my sides is 90mm in the tail block instead of 100mm according to my plans.So, i am thinking of reducing the body depth to 90mm and i would like to know how much will this affect the sound of the guitar.
Would it be better to redo the sides with a pair of you rosewood?
All the help is needed

Many thanks

Yiannis
Author:  jonsse [ Wed Feb 17, 2010 12:06 pm ]
Post subject:  Re: Body depth problem from a new member
Hi Yannis

Just reduce the depth of the guitar as suggested. You wont notice any change in sound.
Anyway you wont know what it would have sounded like anyway.so it doesn't matter ! kind of guitar paradox.

Regards
Peter
Author:  SteveCourtright [ Wed Feb 17, 2010 12:17 pm ]
Post subject:  Re: Body depth problem from a new member
Yannis,

You are are the point where making a new set of sides is not a big set back. You should develop the habit, since I am sure that you will build more guitars (!), to do things properly, even if it takes a little longer.

A guitar with a reduction in internal volume from the designed specification will not sound the same as one with a full depth. You don't want to put in the many hours finishing the building of this guitar only to wonder later if it was a waste of time if it does not come out as expected.
Author:  Darrin D Oilar [ Wed Feb 17, 2010 12:29 pm ]
Post subject:  Re: Body depth problem from a new member
That's why I don't use plans. :)

Seriously on my first two builds I've managed to screw up the body depth both times. I failed to take the back radius into account when cutting the neck block height. The first one sounds good to me and to those who've played it. The second one is on hold until I get my shop up and going again.

I would imagine that there are all kinds of things that will negatively affect the sound outside of decreasing the body volume. If it were me I would press on and not worry about it.

Darrin
Author:  WudWerkr [ Wed Feb 17, 2010 12:39 pm ]
Post subject:  Re: Body depth problem from a new member
If this isnt a commission build , I would go with the 90mm and forget about it . as was stated the diffrence will not be noticable in that small a change.
Author:  Howard Klepper [ Wed Feb 17, 2010 12:46 pm ]
Post subject:  Re: Body depth problem from a new member
You can extend the liners to make up the difference.
Author:  rmcctr [ Wed Feb 17, 2010 1:04 pm ]
Post subject:  Re: Body depth problem from a new member
Hello again,
Thanks for your answers.
I was considering in rebuilding new sides but since i am in Greece and i buy everything from internet i amm afraid i wont be able to match the new sides with my back.
Dear Howard What are the liners because in technical terms i am not very good idunno

Anyway thanks again
Yiannis
Author:  Laurent Brondel [ Wed Feb 17, 2010 1:10 pm ]
Post subject:  Re: Body depth problem from a new member
Liners=kerfed liners, or kerfing as it is called sometimes. as Howard wrote, you can glue the liners proud of the sides, no prouder than the height of your bindings. And glue mahogany spacers on the head and tail blocks.
Author:  SteveCourtright [ Wed Feb 17, 2010 1:12 pm ]
Post subject:  Re: Body depth problem from a new member
rmcctr wrote:
Hello again,
Thanks for your answers.
I was considering in rebuilding new sides but since i am in Greece and i buy everything from internet i amm afraid i wont be able to match the new sides with my back.
Dear Howard What are the liners because in technical terms i am not very good idunno

Anyway thanks again
Yiannis


The liners or lining or kerfed linings are the strips of wood that form the connection between the sides and the top and back plates. Howard is correct - you can extend the liners above the edge of the sides to give you the necessary depth.
Author:  rmcctr [ Wed Feb 17, 2010 2:50 pm ]
Post subject:  Re: Body depth problem from a new member
Here are some photos of my progress so far.
Be nice with your comments, this is my first attemt [:Y:]
Author:  Randolph [ Wed Feb 17, 2010 3:38 pm ]
Post subject:  Re: Body depth problem from a new member
Hi Yiannis. Your guitar looks good. Have you started to work with those braces yet? One question I have: Is your upper transverse brace (the one above the soundhole) scalloped? It looks from the picture like it is. If it is, you will want to scrape it off and make a new one that is not sturcturally compromised in that spot. That brace needs to keep the fretboard extension from caving the top of the guitar above the soundhole in. If it is not scalloped, ignore what I just said.

The kerfed lining can be held up above the line of the sides a little bit and since this is what the top glues to, it will extend your body depth wherever you hold it up. Make sense? When you cut the rabbet for your binding and purfling, the fact that the lining is up from the sides will go away. Don't hold it up more than the thickness of your purfling. Good luck.
Author:  rmcctr [ Sat Feb 20, 2010 9:45 am ]
Post subject:  Re: Body depth problem from a new member
Quote:
Hi Yiannis. Your guitar looks good. Have you started to work with those braces yet? One question I have: Is your upper transverse brace (the one above the soundhole) scalloped? It looks from the picture like it is. If it is, you will want to scrape it off and make a new one that is not sturcturally compromised in that spot. That brace needs to keep the fretboard extension from caving the top of the guitar above the soundhole in. If it is not scalloped, ignore what I just said.

Hi Randolph,
Please if you can explain better because i don't understand the technical terms you use.What do you mean that the transverse brace should not be sturcturally compromised in that spot?

Best regrds

Yiannis
Author:  Mike Lindstrom [ Sat Feb 20, 2010 11:59 am ]
Post subject:  Re: Body depth problem from a new member
On the shallow body depth -- I did exactly the same thing on my first guitar. I was in a class and afraid of falling behind, so I just ran with it. Turned out fine.

On your bracing -- Scalloping is carving away material from the braces to have high and low spots. The upper transverse brace (the big one between the sound hole and the neck) is structurally important and should not be scalloped (material carved away in the middle). In the photograph you posted it appears that material was removed from that center area. The other braces are often carved away to make things lighter and more musical, but the upper bout of the guitar is less significant in the production of sound.

Good luck. It's sure is fun.

Mike
Author:  mhammond [ Sat Feb 20, 2010 11:31 pm ]
Post subject:  Re: Body depth problem from a new member
Yiannis:
Your guitar looks good, I hope you are having fun. The upper transverse brace needs to be taller in the middle to resist the forces that come from the fretboard and neck. You might also check the thickness of your bridge plate, it looks like it might be a little too heavy. Its much easier to change these things now, after the top is glued on its very difficult to do any changes. Keep going, I am sure the guitar will sound wonderful when finished! Mikey
Author:  rmcctr [ Tue Feb 23, 2010 4:49 am ]
Post subject:  Re: Body depth problem from a new member
In my plans and the upper brace is scalloped in the middle.
As for the bridge plate is 2,5mm thick.Do i need to sand it more?
Author:  Dave Fifield [ Tue Feb 23, 2010 5:06 am ]
Post subject:  Re: Body depth problem from a new member
Hi Yiannis! Welcome to the OLF!!

Howard et al have the answer for you. You should easily be able to add 5mm to each edge of the sides (ribs) at the upper bout where you are 10mm short. Glue the kerfed liner onto the sides so it sticks up over of the edge by, say, 7mm (a couple of mm extra to allow for sanding to fit the soundboard and back later). Close the box normally, then, when you cut the binding channels, the binding on the soundboard and back edges will fill in the missing 10mm on the sides.

It's not only new members who have body depth problems. Many luthiers that I've met (including me), and have both a body depth and width problem - mainly due to eating too much food and not getting enough exercise! laughing6-hehe

Cheers,
Dave F.
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