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 Post subject: backing a crack
PostPosted: Fri Sep 25, 2009 10:58 am 
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Joined: Sun May 10, 2009 9:33 am
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First name: Kent
Last Name: Bailey
City: Florissant
State: Colorado
Zip/Postal Code: 80816
Country: usa
Focus: Build
Status: Amateur
I keep running into issues with this guitar renovation ..... I seem to (NOW after filling cracks and sanding) have some thin spots in my back near the tail piece that might need some backing. It's thin enough that finger pressure in the wrong place might recrack it. Any recommendations? I expect 2 of the areas to be reinforced would be about 3"X 3". Fabric? thin veneer? apply veneer cross grain or with grain to the back?
Kent Bailey

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 Post subject: Re: backing a crack
PostPosted: Fri Sep 25, 2009 11:21 am 
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Joined: Fri Apr 13, 2007 12:52 am
Posts: 295
Location: Canada
First name: Cal
Last Name: Maier
City: Crossfield
State: AB
Country: Canada
Focus: Build
Kent,

I would apply a thin veneer of the same species cross grain to the areas, if you suspect the cracks may open up again with time, this should help prevent that and add some stiffness to the weak spots.
This is one of the reasons when doing this type of work I try to stay away from sanding as much as possible. I will glue my filler strip in proud of the surface and bring it flush with a scraper.

Cal

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 Post subject: Re: backing a crack
PostPosted: Fri Sep 25, 2009 6:04 pm 
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Koa
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Joined: Wed Mar 16, 2005 2:30 pm
Posts: 1041
Location: United States
Kent,
I agree with Cal that cross grained veneers in those weak areas will serve your purpose of reinforcing
them well. A suggestion for clamping those veneers sections in place is something that I've done for
years with good results.

I keep a huge selection of different size rare earth magnets in my shop for specialty clamping
applications like this. Spread your glue on the veneer piece and clamp it securely in place using a
magnet on the inside matched by another on the outside. These little magnets can easily generate
15 to 25 pounds per square inch when they're pulling against one another depending on the size
you're using.

Just place the pairs evenly across the veneer, concentrating them in the area of the crack and you'll
get a very secure and long lasting reinforcement for those thin areas.

I get all of my magnets from www.magcraft.com. The prices are very reasonable for the amount of
work you can do with them.

Hope that helps a little,
Kevin Gallagher/Omega Guitars


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 Post subject: Re: backing a crack
PostPosted: Fri Sep 25, 2009 6:23 pm 
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Koa
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Posts: 1825
Location: Grover NC
First name: Woodrow
Last Name: Brackett
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State: NC
Zip/Postal Code: 28073
Country: USA
Focus: Build
Like Kevin said, magnets work great. Be careful and don't let one.....get away and cause a dent. I normally use a small scrap on the outside between the magnet and top or back to keep from scaring it.

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 Post subject: Re: backing a crack
PostPosted: Fri Sep 25, 2009 6:37 pm 
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Koa
Koa

Joined: Wed Mar 16, 2005 2:30 pm
Posts: 1041
Location: United States
I should have mentioned that Woody. I always take my new magnets and apply a felt pad to one side of each.
This allows me to choose the padded side or the bare side when using them. It's a good idea to protect the
wood from the magnets since thay can very easily put a dent in it.

Regards,
Kevin Gallagher/Omega Guitars


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 Post subject: Re: backing a crack
PostPosted: Fri Sep 25, 2009 7:22 pm 
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Koa
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Posts: 1825
Location: Grover NC
First name: Woodrow
Last Name: Brackett
City: Grover
State: NC
Zip/Postal Code: 28073
Country: USA
Focus: Build
Kevin Gallagher wrote:
I should have mentioned that Woody. I always take my new magnets and apply a felt pad to one side of each .........................................................................................................................................................................................................................

Regards,
Kevin Gallagher/Omega Guitars



I just give myself a big slap in the back of the head. I've wrestled with little pieces of spruce and such for years to protect whatever I was using the magnets on. I guess I'll get some glue and felt. [clap]

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 Post subject: Re: backing a crack
PostPosted: Fri Sep 25, 2009 7:31 pm 
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Koa
Koa

Joined: Fri Sep 30, 2005 10:33 pm
Posts: 954
Location: United States
Me too Woody, dang self-adhesive felt....geez!

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