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Old 04-24-2014, 11:36 AM
bond_fan bond_fan is offline
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Default Sound Board Dimensions

Hi!

I'm going to be cutting up some Pernambuco and Amazon Rosewood for acoustics and was wondering is there a consensus of how thick, wide & long the back and the sides should be or does it vary for each builder on how thick they prefer the boards? The Pernambuco is flat sawn while the AMR is radial and vertical grain.

Dreadnaught size?

Classical OM?

Thanks!

Last edited by bond_fan; 04-24-2014 at 12:01 PM. Reason: Added text.
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Old 04-24-2014, 01:53 PM
arie arie is offline
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i might suggest browsing these sites to see what sizes are being made available:

http://rctonewoods.com/RCT_Store/

http://www.alliedlutherie.com/
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Old 04-24-2014, 05:16 PM
LouieAtienza LouieAtienza is offline
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Quote:
Originally Posted by bond_fan View Post
Hi!

I'm going to be cutting up some Pernambuco and Amazon Rosewood for acoustics and was wondering is there a consensus of how thick, wide & long the back and the sides should be or does it vary for each builder on how thick they prefer the boards? The Pernambuco is flat sawn while the AMR is radial and vertical grain.

Dreadnaught size?

Classical OM?

Thanks!
It does vary by builder, by species... there are many different factors. Usually with well-quartered tropical hardwoods they can be worked thinner, but wiith flatsawn boards, you might want to keep them thicker. In either case youu'd want to leave them thicker than you need so you leave room to sand or scrape to final thickness.
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Old 04-24-2014, 07:40 PM
Ned Milburn Ned Milburn is offline
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Generally, for backs you want 8.5 inches in width, 22 inches in length, and 4 to 5 mm in thickness for rough cuts. Sides, 33 inches should do for length and 4 inches for width, thickness 4 to 5mm is fine.

Check the dimensions of the guitar(s) you are interested in building and work from that, since there is considerable variation. Give yourself about a half inch extra width and a couple inches extra length for the back. Sides don't need so much extra width, since they will be bound anyhow.
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Old 04-24-2014, 08:02 PM
John Arnold John Arnold is offline
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These are the minimum dimensions I try to stick with.

Dreadnought
Backs 8 X 21
Sides 4 3/4 X 32

000 (OM)
Backs 7 3/4 X 20 1/2
Sides 4 X 31

Classical
Backs 7 1/2 X 20 1/4
Sides 4 X 30

Thickness depends on the smoothness of a sawn surface, but I tend to err on the thick side. Rough sawn minimum for backs is around 0.160", sides around 0.140".
Sanded backs 0.130" (Martin joining thickness for backs)
Sanded sides 0.100"

Quote:
Sides, 33 inches should do for length and 4 inches for width,
Quote:
Sides don't need so much extra width, since they will be bound anyhow.
Standard dreadnought depth is 4 7/8" at the butt. If you subtract the thickness of top and back, you still need at least 4 5/8". I use thin binding, which does not help much.
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Old 04-25-2014, 03:47 AM
bond_fan bond_fan is offline
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Thanks everyone for their replies!

There still isn't a consensus, but since I'm only keeping one set of each for myself and the rest for sale I suppose it's best to error thickness wise a bit thicker...

My friend has both a wide joiner and one of those 20" belt sander planers, and his band saw is one of those really nice ones so we can almost cut to just the blade with and only have that much loss. I think we can get nice tolerances.

I think I'll try to go with and not leave the thickness rough:

Backs - L 22" x W 8" x T 4mm = .157

Sides - L 32" x W 5" x T 4mm = .157

That way a person has the option to make a dreadnaught or OM. The Pernambuco is 8" & 6.5", so I can even leave the full width, while the Amazon Rosewood has more constraints by width...



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