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backing a crack
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Author:  Bailey [ Fri Sep 25, 2009 10:58 am ]
Post subject:  backing a crack
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
Author:  Cal Maier [ Fri Sep 25, 2009 11:21 am ]
Post subject:  Re: backing a crack
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
Author:  Kevin Gallagher [ Fri Sep 25, 2009 6:04 pm ]
Post subject:  Re: backing a crack
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
Author:  woody b [ Fri Sep 25, 2009 6:23 pm ]
Post subject:  Re: backing a crack
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.
Author:  Kevin Gallagher [ Fri Sep 25, 2009 6:37 pm ]
Post subject:  Re: backing a crack
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
Author:  woody b [ Fri Sep 25, 2009 7:22 pm ]
Post subject:  Re: backing a crack
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]
Author:  GregG [ Fri Sep 25, 2009 7:31 pm ]
Post subject:  Re: backing a crack
Me too Woody, dang self-adhesive felt....geez!
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