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1981 1113 Classic...

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BanjoJ
Posted 2016-05-16 4:34 PM (#525295 - in reply to #524970)
Subject: RE: 1981 1113 Classic...



Joined:
September 2012
Posts: 778

Location: Thredbo, NSW, Australia
Very impressive Dan.

I'm wondering if grain direction is a factor with the braces. Would quarter sawn be better, and if so should the grain be vertical or horizontal?
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DanSavage
Posted 2016-05-16 8:19 PM (#525300 - in reply to #525295)
Subject: RE: 1981 1113 Classic...



Joined:
June 2012
Posts: 1949

Location: Lake Forest, CA

BanjoJ - 2016-05-16 2:34 PM

Very impressive Dan.

I'm wondering if grain direction is a factor with the braces. Would quarter sawn be better, and if so should the grain be vertical or horizontal?


Howdy Paul!

Thanks!

Actually, these are quarter-sawn wood. The previous photo is a bit of an optical illusion. The end of the brace you're seeing is beveled and rounded, so it makes the grain seem more flat-sawn than it really is. Here's a few photos that show the actual angle of the grain for each transverse brace.

The runout of the wood isn't anything to write home about, and I certainly wouldn't use this wood on an airplane (more about that shortly) but it's acceptable for guitars. I've read that anything less than 30-degrees will work for either top wood or brace stock.

Brace #1

Brace #2

Brace #3

Brace #4

In contrast, here's the grain of the original braces. A couple approach what would be considered flat-sawn, but given the hectic production schedule and limited resources, it works. Also notice that only one piece is a true 3/16" thick. The others are about 7/32".

WRT grain orientation, most luthiers like to have the grain on the braces stock orientated in a vertical plane. In contrast, when building for aviation, the grain is usually orientated in the horizontal plane.

Some have done tests and the wood is pretty much equally strong in either direction. It all gets down to intentions. The wood in airplanes, for example, in stringers, is usually not carved. But, guitar braces cane be both tapered and scalloped.

If the grain for guitar braces were oriented in the horizontal plane, it would tend to split along the grain when scalloped with a chisel. When the grain is oriented in the vertical plane it can be scalloped and tapered without spliting.

When I was building my model airplanes, I always oriented the grain so that the grain was parallel to whatever surface it was closest to.

When I was re-topping Jay's guitar, I bought some wood to use for the brace stock from Aircraft Spruce because I knew the high standards required for wood used in aviation. I was surprised to find the grain oriented 90-degrees to the wood used in the braces. So, I ended up buying brace stock blanks from Stewmac and cut my own braces so the grain orientation matched that of the original braces.

WRT to grain run-out, the Sitka spruce used for aviation has to have a very limited amount of runout because of the stresses placed upon the pieces when flying. If a guitar brace splits, then the guitar may not sound so good. If an airplane stringer or spar splits because of run-out, someone may die. `Nuff said.



Edited by DanSavage 2016-05-16 8:23 PM
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moody, p.i.
Posted 2016-05-17 12:04 AM (#525310 - in reply to #524970)
Subject: Re: 1981 1113 Classic...


Joined:
March 2002
Posts: 15290

Location: SoCal
Gotta admit, this is exciting.....
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BanjoJ
Posted 2016-05-17 12:38 AM (#525311 - in reply to #525310)
Subject: Re: 1981 1113 Classic...



Joined:
September 2012
Posts: 778

Location: Thredbo, NSW, Australia
Wow! Thanks Dan.

When I repaired the braces in my Folklore I made some test ones out of quarter-sawn. One with the grain running vertical and another horizontal and tested them for stiffness. The vertical were stiffer. But I was only using my fingers for the test, not any fancy test rig.
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DanSavage
Posted 2016-05-17 2:28 PM (#525334 - in reply to #525310)
Subject: Re: 1981 1113 Classic...



Joined:
June 2012
Posts: 1949

Location: Lake Forest, CA

moody, p.i. - 2016-05-16 10:04 PM

Gotta admit, this is exciting.....


Yep. Getting closer. I'm really looking forward to hearing how it sounds.

Transverse braces glued and clamped.



Fan braces glued and clamped.



I'll pull the top out of the gobar deck tomorrow, and finish making the bridge-clamping cawl and start prepping the top for gluing to the bowl.

That mainly consists of masking for the bridge and spraying the base coat of polyurethane and sanding it smooth. If all goes well I should have the top glued to the bowl by this weekend.

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moody, p.i.
Posted 2016-05-17 2:58 PM (#525335 - in reply to #524970)
Subject: Re: 1981 1113 Classic...


Joined:
March 2002
Posts: 15290

Location: SoCal
Cool. What do all the clamps attach to above the guitar? Do you have a pic of that?
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DanSavage
Posted 2016-05-17 5:28 PM (#525342 - in reply to #525335)
Subject: Re: 1981 1113 Classic...



Joined:
June 2012
Posts: 1949

Location: Lake Forest, CA

moody, p.i. - 2016-05-17 12:58 PM

Cool. What do all the clamps attach to above the guitar? Do you have a pic of that?


Sure thing. It's called a gobar deck. I bought this one from Blues Creek Guitars for $95. Stewmac sells them for $482. (!)

The round fiberglass rods with rubber feet came with the gobar deck, but Blues Creek sells them separately. Each rod exerts about 7 lbs. of force, depending on how much they bend. The bars just push against the underside of the upper plate.

I made my own version of this to joint the soundboards. Here's the soundboard for my 1617 being glued together. The wooden wedges on the right are clamped to squeeze the two pieces together and the gobars are pushing down on the joint to keep the two pieces even with each other while the glue dries.

Before applying the glue, I clamped the two pieces in the deck, then applied the tape. I remove the top from the deck and the tape acts like a hinge so I can fold the two pieces back and apply the glue to the edges. Then, I flatten the top and put it into the deck.



Edited by DanSavage 2016-05-17 5:29 PM
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moody, p.i.
Posted 2016-05-17 6:01 PM (#525345 - in reply to #524970)
Subject: Re: 1981 1113 Classic...


Joined:
March 2002
Posts: 15290

Location: SoCal
All that coolness right in front of the washing machine.....
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DanSavage
Posted 2016-05-17 6:03 PM (#525346 - in reply to #524970)
Subject: Re: 1981 1113 Classic...



Joined:
June 2012
Posts: 1949

Location: Lake Forest, CA
The washing machine is on SWMBO's side of the garage. All the coolness is on my side.
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DanSavage
Posted 2016-05-18 10:26 PM (#525367 - in reply to #524970)
Subject: RE: 1981 1113 Classic...



Joined:
June 2012
Posts: 1949

Location: Lake Forest, CA

Fan braces are done. Now it's time to build the bridge-claming cawl.

Lower set from 1/2" medium balsa.

Upper set from 1/2" medium balsa.

Topped with 1/4" marine (birch) ply.



And, here's what it looks like all assembled.



Top is wetted out with naptha to show the grain. The top will have a skunk-stripe all its own.



Bridge masking is in place.



Fretboard masking is in place. All ready to spray the base coats onto the top.




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arumako
Posted 2016-05-19 9:42 AM (#525376 - in reply to #524970)
Subject: Re: 1981 1113 Classic...



Joined:
October 2012
Posts: 846

Location: Yokohama, Japan
Awesome Dan! I'm learning so much again from your amazing work and documentation. Thank you! The discussion about the wood grain in the braces is so interesting. Also, I never would have imagined making a bridge caul out of balsa! How much clamping pressure can balsa take? Very cool!
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DanSavage
Posted 2016-05-19 11:34 AM (#525378 - in reply to #524970)
Subject: Re: 1981 1113 Classic...



Joined:
June 2012
Posts: 1949

Location: Lake Forest, CA
Hi Ken,

Thanks.

Generally speaking balsa is pretty strong, depending on the weight. Balsa is classified according to 1-cubic-foot blocks.

Ultra-Light: 4-5 lb.
Light: 5-6 lb.
Medium: 7-9 lb.
Hard: 14+ lb.

The wood I used above would be considered medium. I got several scraps of it when I ordered contest balsa. (Light) The stack of contest balsa was plastic-wrapped to the 1/2" plank to keep the lighter wood from getting crushed during shipping.

While it doesn't have the compressive strength of spruce, it's not going to be crushed by the pressures needed to clamp a bridge. You wouldn't want to clamp wood joints too tightly, anyway as you'll squeeze out all the glue. That would result in a starved joint which would be weak and prone to failure.

Edited by DanSavage 2016-05-19 11:35 AM
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arumako
Posted 2016-05-20 1:05 PM (#525401 - in reply to #525378)
Subject: Re: 1981 1113 Classic...



Joined:
October 2012
Posts: 846

Location: Yokohama, Japan
DanSavage - 2016-05-19 1:34 AM

Hi Ken,

Thanks.

Generally speaking balsa is pretty strong, depending on the weight. Balsa is classified according to 1-cubic-foot blocks.

Ultra-Light: 4-5 lb.
Light: 5-6 lb.
Medium: 7-9 lb.
Hard: 14+ lb.

The wood I used above would be considered medium. I got several scraps of it when I ordered contest balsa. (Light) The stack of contest balsa was plastic-wrapped to the 1/2" plank to keep the lighter wood from getting crushed during shipping.

While it doesn't have the compressive strength of spruce, it's not going to be crushed by the pressures needed to clamp a bridge. You wouldn't want to clamp wood joints too tightly, anyway as you'll squeeze out all the glue. That would result in a starved joint which would be weak and prone to failure.

Thanks for replying Dan. I never realized balsa was able to withstand that kind of pressure. I remember my Dad used to work with balsa in his wood shop, and he would give me scraps that I used to carve and cut into wooden boats. Balsa always seemed soft and buoyant, but never strong.

I'll need to do a bit more research on balsa as I'm planning on using thin balsa strips to sandwich my CFRP braces for my CC54i iDea Project! Very cool information! Thanks again!
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DanSavage
Posted 2016-05-20 2:48 PM (#525402 - in reply to #525401)
Subject: Re: 1981 1113 Classic...



Joined:
June 2012
Posts: 1949

Location: Lake Forest, CA
Yep, balsa is bouyant. Kon Tiki was made from balsa logs.

I use balsa for the cawls because it's softer than the underlying wood and won't leave marks or dents. Also because, like you say, it's easier to cut and carve thick planks.
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Geostorm98
Posted 2016-05-20 4:57 PM (#525407 - in reply to #524970)
Subject: Re: 1981 1113 Classic...



Joined:
September 2011
Posts: 402

Location: New Hartford CT
Dan, your work is incredible. What a wonderful contributor to the OFC you are. Keep it up.
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jay
Posted 2016-05-20 10:14 PM (#525415 - in reply to #525407)
Subject: Re: 1981 1113 Classic...



Joined:
January 2009
Posts: 1224

Location: Texas

Dan, your work is incredible. What a wonderful contributor to the OFC you are. Keep it up.

+1 

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DanSavage
Posted 2016-05-21 2:39 PM (#525424 - in reply to #524970)
Subject: Re: 1981 1113 Classic...



Joined:
June 2012
Posts: 1949

Location: Lake Forest, CA
Thanks, guys.

I sprayed the first coat of sealer on this morning and was surprised by the amount of figuring of the wood. It's definitely going to have a vintage Ovation look to it.
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moody, p.i.
Posted 2016-05-21 6:36 PM (#525426 - in reply to #524970)
Subject: Re: 1981 1113 Classic...


Joined:
March 2002
Posts: 15290

Location: SoCal
Cool....
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moody, p.i.
Posted 2016-05-21 7:12 PM (#525428 - in reply to #524970)
Subject: Re: 1981 1113 Classic...


Joined:
March 2002
Posts: 15290

Location: SoCal
A photo?
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DanSavage
Posted 2016-05-21 7:53 PM (#525429 - in reply to #524970)
Subject: RE: 1981 1113 Classic...



Joined:
June 2012
Posts: 1949

Location: Lake Forest, CA

It's difficult to capture the figuring, but these pics show it as well as can be expected.

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moody, p.i.
Posted 2016-05-21 8:18 PM (#525430 - in reply to #524970)
Subject: Re: 1981 1113 Classic...


Joined:
March 2002
Posts: 15290

Location: SoCal
Thanks. That's a good looking piece of wood. I'm getting very excited....

Edited by moody, p.i. 2016-05-21 8:19 PM
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DanSavage
Posted 2016-05-21 8:30 PM (#525431 - in reply to #525430)
Subject: Re: 1981 1113 Classic...



Joined:
June 2012
Posts: 1949

Location: Lake Forest, CA
This guitar will be a one-of-a-kind guitar.

It'll be the only Ovation classical in the world with torrefied Adi top and braces.
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moody, p.i.
Posted 2016-05-21 9:30 PM (#525433 - in reply to #524970)
Subject: Re: 1981 1113 Classic...


Joined:
March 2002
Posts: 15290

Location: SoCal
I suspect that the sound will "pop". But we'll find out....
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DanSavage
Posted 2016-05-21 11:33 PM (#525436 - in reply to #525430)
Subject: Re: 1981 1113 Classic...



Joined:
June 2012
Posts: 1949

Location: Lake Forest, CA
Yep. As they say the proof of the pudding is in the tasting...
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ksdaddy
Posted 2016-05-22 9:49 PM (#525449 - in reply to #524970)
Subject: Re: 1981 1113 Classic...


Joined:
April 2003
Posts: 603

Location: Caribou, ME
I'm not going to show these pics to the guy who sold me that guitar. He'll never sell me any more cheapies!
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