Shaping Braces for an OM 28
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Re: Shaping Braces for an OM 28
'Very nice shaping on those braces.
I will try to emulate this as best I can."
The pdf is excellent thanks to the cad creator of it
print it in 1-1 scale, and match brace shape to paper templates.
or spray glue to thicker paper and cut.
or Scan it and convert to digital.
I will try to emulate this as best I can."
The pdf is excellent thanks to the cad creator of it
print it in 1-1 scale, and match brace shape to paper templates.
or spray glue to thicker paper and cut.
or Scan it and convert to digital.
You do not have the required permissions to view the files attached to this post.
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Re: Shaping Braces for an OM 28
The braces are close to what they should be
do not over shape the braces . You do want to round the braces and sand them pretty. If you go too far the top will rotate and sink in at the top in front of the braces.
Think of it this way The upper part of the braces are holding the compressive loads and the lower part are in tension. You take too much off the upper you will have structural issues.
You don't want the braces under a 1/2 in height at the X and no lower the 5/16 at the lower part of the scallop
do not over shape the braces . You do want to round the braces and sand them pretty. If you go too far the top will rotate and sink in at the top in front of the braces.
Think of it this way The upper part of the braces are holding the compressive loads and the lower part are in tension. You take too much off the upper you will have structural issues.
You don't want the braces under a 1/2 in height at the X and no lower the 5/16 at the lower part of the scallop
John Hall
Blues Creek Guitars Inc
Authorized CF Martin Repair Center
president of Association of Stringed Instrument Artisans
http://www.bluescreekguitars.com
Blues Creek Guitars Inc
Authorized CF Martin Repair Center
president of Association of Stringed Instrument Artisans
http://www.bluescreekguitars.com
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Re: Shaping Braces for an OM 28
John
Thanks so much for the heads up on this.
I definitely might have taken too much off of the X brace scallops which would have been bad.
I assume there is less concern with the upper and lower tone bars and treble and bass finger braces.
Correct me if I' wrong.
Thanks so much for the heads up on this.
I definitely might have taken too much off of the X brace scallops which would have been bad.
I assume there is less concern with the upper and lower tone bars and treble and bass finger braces.
Correct me if I' wrong.
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Re: Shaping Braces for an OM 28
Remember - stiffness primarily comes from height, not width, and in shaving down the braces you're trying to reduce mass, not stiffness. At least that's my take on it. So I tend to make braces narrower, not necessarily lower.
Of course you also want to get the stiffness correct, too....
Of course you also want to get the stiffness correct, too....
Don't believe everything you know.
Anything is possible if you don't know what you are talking about.
When things are bad, try not to make them any worse, because it is quite likely they are bad enough already. - French Foreign Legion
Anything is possible if you don't know what you are talking about.
When things are bad, try not to make them any worse, because it is quite likely they are bad enough already. - French Foreign Legion
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Re: Shaping Braces for an OM 28
Main got it right its about mass Physics, heavier it is the harder it is to get it to move. Make it too light and it won't support the load
John Hall
Blues Creek Guitars Inc
Authorized CF Martin Repair Center
president of Association of Stringed Instrument Artisans
http://www.bluescreekguitars.com
Blues Creek Guitars Inc
Authorized CF Martin Repair Center
president of Association of Stringed Instrument Artisans
http://www.bluescreekguitars.com
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Re: Shaping Braces for an OM 28
I tried to take all of your excellent input and here is the result.
Struggled a bit using a chisel as I don't have a lot of experience but it wasn't too bad.
Struggled a bit using a chisel as I don't have a lot of experience but it wasn't too bad.
You do not have the required permissions to view the files attached to this post.
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Re: Shaping Braces for an OM 28
That looks GREAT. You did a fine job. Nice and neat too.
Well done
Well done
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Re: Shaping Braces for an OM 28
nice work
if you tape on it what note do you get? You want the top and back to be a semi tone apart avoid harmonic notes
if you tape on it what note do you get? You want the top and back to be a semi tone apart avoid harmonic notes
John Hall
Blues Creek Guitars Inc
Authorized CF Martin Repair Center
president of Association of Stringed Instrument Artisans
http://www.bluescreekguitars.com
Blues Creek Guitars Inc
Authorized CF Martin Repair Center
president of Association of Stringed Instrument Artisans
http://www.bluescreekguitars.com
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Re: Shaping Braces for an OM 28
I tap the top and back to make sure they sound different. You don't want them singing the same note (usually there's no problem). I also listen to the top for resonance and sustain. I don't go below .75" tall at the X. If I don't feel and hear sustain and resonance, I take a little off the lower x's or tone bars, very little.
When you first start building, it's best to stick to tried and true measurements. It's easy to over trim. Tap and listen, also feel the vibration. You'll soon get the feel for how much should come off, some tops more than others.
When you first start building, it's best to stick to tried and true measurements. It's easy to over trim. Tap and listen, also feel the vibration. You'll soon get the feel for how much should come off, some tops more than others.