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 Post subject: gluing on the back: fail
PostPosted: Tue Nov 04, 2008 9:25 pm 
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Brazilian Rosewood
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Let me be the first to tell you that rubber band clamping does not work. The problem is that rubber bands does not provide sufficient clamping pressure to insure a good bond between the top/back and the side. If it does provide a good clamping pressure they are often in the wrong place resulting in the joint being forced wide open. I think a better option would be a go-bar deck/radius dish or lots of cam clamps or spool clamps. Good thing I took the entire thing apart before the damage becomes irreversible. Do a dry run before clamping to make sure all joints will close properly.

Also when working with hot hide glue since there are a lot of area to be glued how do I make sure the glue is open long enough for me to set the large number of clamps set? or most people here simply doesn't use hide glue for top/back to side joints?

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PostPosted: Tue Nov 04, 2008 9:41 pm 
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Koa
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With hide glue, you will have to move very quickly. Personally, I use Titebond Original for most of the structural joints in my guitars. There is plenty of open time and it has a massive track record as being an excellent glue. I attach the back to the sides first via clamps - I place the back on a radius dish to ensure proper geometry is kept. I then attach the top to the sides with the "roping" method. It is a very effective method and if done properly, you will never have joint failure.

If you are set on using animal glue, I would recommend using fish glue for attaching the plates to the sides - you will have a lot more open time.

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PostPosted: Tue Nov 04, 2008 9:43 pm 
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Brazilian Rosewood
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my last 26 guitars have been glued using the rubber band method.... none has failed. I use a rubber band (tire inner tube) in a "roping" fashion and it works great.

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PostPosted: Tue Nov 04, 2008 9:48 pm 
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My guess though Peter is that you don't use HHG for attaching the plates.

Yes, you have to move fast when using HHG for attaching your plates. A go-bar deck I think would be fastest, clamps the slowest. If all you have are clamps what you have to do is work in stages just like they use to do making double bases. Glue a section, clamp it down. Warm the next section right up to the previous one (which is still clamped). Add some more glue, clamp it down etc... You don't have to wait till the glue is fully set, you can just work in stages.

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PostPosted: Wed Nov 05, 2008 8:29 am 
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Brazilian Rosewood
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rahimiiii the first guitar I ever built was using the Sloan method with the hooks and rubber bands. It worked fine but I was using huge rubber bands too, perhaps you are not using big enough bands?

I now use the tire tube roping method from Cumpliano and Natelson and it's perfect.


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PostPosted: Wed Nov 05, 2008 1:58 pm 
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Cocobolo
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I have tried a number of methods to glue tops and backs onto the rims. It is hard to beat the simplicity of using a go-bar deck, but there dozens of ways to skin that cat. I like titebond or LMI white glue for those joints because of the open working time.

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PostPosted: Fri Nov 07, 2008 8:25 am 
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Walnut
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With any of the methods you should keep in mind that there is such thing as too much pressure. All that is required is enough pressure distributed evenly to hold the pieces together until the glue sets up. Too much pressure can squeeze the glue out and starve the joint.

"Point loading" can be a problem with any method if you don't distribute the load evenly. It sounds like you may have experienced that. Too much space between the clamps, rope, rubber bands or go bars can cause a pillowing effect where the wood is held under the clamp and raises up between them. More pressure just increases the problem. It is best to use more lightly applied clamps than fewer tight clamps.

The other really nice thing about hide glues is that if you do get a pillow somewhere it is no big deal to heat the area, apply hot water and maybe some thinned glue with a brush and re-clamp. Collagen based glues are the only ones I am aware of that give you this option and still bond as good as they originally would have.

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