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PostPosted: Fri Aug 15, 2014 9:57 pm 
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Joined: Wed Sep 08, 2010 12:17 am
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First name: John
Last Name: Arnold
City: Newport
State: TN
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Country: USA
Focus: Repair
Status: Professional
Quote:
I'd love to see the proof that Titebond is more forgiving. A real example not an opinion please.

It's not been my experience. Neither glue tolerates a poor fit.

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PostPosted: Fri Aug 15, 2014 11:10 pm 
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Koa
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First name: Lonnie
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John I agree with you on this


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PostPosted: Sat Aug 16, 2014 6:12 am 
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Brazilian Rosewood
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that is a fact about tite bond . It can fill gaps as much as .010
these are 2 different glues , HHG and Fish are drying glues , they loose volume as water evaporates while tite bond is a curing glue. Since you may not believe what I will tell you prove it to your self with this simple experiment. Put gaps in glue samples and see what the strength of the joint are.
You will see the nicer the joint the better the joint . Tite bond was better at filling gaps up to about .010. After that the glue joint strength fall of considerably.
Fish and HHG drop off at about .005. You do the same and see if your results are not similar. Tite bond is actually stronger than HHG and fish under most circumstances but any glue that is stronger than the wood you are gluing is perfect. Often we look at repairability . There is a lot of info on the net and not all is good info. As an engineer I look for where the tests were done. The below link was done in a lab so the results are more consistent.

Along with this , there is clamping technique , and this can also lead into trouble. Wood glues require about a 10 lb per sq in clamping force. There is no need to over clamp a joint. Get the mating surfaces true and your good to go. Make a cawl to to fit under your bridge so you are not deforming the top or bridge and keeping the mating surface true.
While the bridge cawls are handy , 3 C clamps will not deform the top where the cawl being clamped in the center and the out side wings will push down bowing the bridge. If there is not cawl under it , you can create a gap between the surface of the joint.
this is also an interesting read.

http://www.oldbrownglue.com/images/arti ... ue_FWW.pdf

How I glue a bridge

https://www.youtube.com/watch?v=P2-kXK_Nt38

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These users thanked the author bluescreek for the post: TimAllen (Sat Aug 16, 2014 8:46 am)
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PostPosted: Sat Aug 16, 2014 3:29 pm 
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timoM wrote:
The mating surface needs to be as perfect as you can make it.

Tim

Important in terms of individual joints but even more important in terms of the tonal response of the guitar. Build a guitar full of poor joints filled with glue and it is a tone sponge.....!! All the small things add up...!!
Tom

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PostPosted: Sat Aug 16, 2014 4:01 pm 
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Brazilian Rosewood
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I do totally agree that in any case , if you have to force a joint , your joint is doomed to fail. If you make guitars and cannot make a good joint you will never make a guitar to its best potential.

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PostPosted: Sat Aug 16, 2014 7:22 pm 
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Koa
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Location: Caves Beach, Australia
John. that test you refer to is deeply flawed, even if it the actual load testing was carried out in a laboratory.

The choice of a brindle joint, unclamped other than to hold the pieces in alignment is a problem in that it does not replicate proper assembly and clamping processes in most other joints.

It is certainly going to give a huge advantage to glues with higher solids content which resist wiping off during assembly, and to water based glues like titebond which swell the surrounding wood


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