The Acoustic Guitar Forum

Go Back   The Acoustic Guitar Forum > General Acoustic Guitar and Amplification Discussion > Build and Repair

Reply
 
Thread Tools
  #16  
Old 07-04-2019, 01:07 AM
Halcyon/Tinker Halcyon/Tinker is offline
Registered User
 
Join Date: Mar 2013
Posts: 2,129
Default

Sure looks like hot melt.

I know in my life, I'm always looking for a good solid bond...
Reply With Quote
  #17  
Old 07-05-2019, 12:33 PM
Alan Carruth Alan Carruth is offline
Registered User
 
Join Date: Feb 2011
Posts: 4,180
Default

I've never seen hot melt that set up clear.

It looks to me as though they butted the end of the finger brace up against the X and then used a drop of epoxy to keep it from peeling up. As has been said, this is not uncommon on the ends of fan braces in the Classical world, but I don't consider it to be good practice.

Most glues have low peel resistance; once an end starts to come up the rest can follow. Pressure on the top above the brace and, or a blow, will cause the top to flex away from the brace, and start it peeling loose. There are two good ways to keep this from happening: either taper the brace down to essentially nothing for some distance back from the end, so that it can flex along with the top, or inlet the end into another brace or the liner so that it can't lift. Some people taper all the brace ends behind the bridge to zero, and it seems to work. In that case the static load is pushing the brace end into the top; doesn't help in the 'impact' scenario, but it's mostly OK. The static load on all the braces in front of the bridge is a peeling load, and those need to be inlet.

For finger braces I've been trimming the ends down to level at, say, 1/8" high where they cross the edge of the X. Leave them enough longer to extend into the X by half it's width (so,1/8" if you're using 1/4" bracing, and so on). Mark where the X crosses the finger brace, and trim the end of the finger down to a wedge shape. Then cut an exact triangular notch into the side of the X brace to fit. When properly done the finger will look like it terminates at the X in a butt joint, but it's inlet and should be well supported. I'll know in 75 years or so whether this worked.
Reply With Quote
  #18  
Old 07-05-2019, 11:15 PM
kavalakat kavalakat is offline
Registered User
 
Join Date: Dec 2010
Posts: 24
Default

Thanks Alan for that detailed explanation.. It's helpful..
Reply With Quote
  #19  
Old 07-08-2019, 12:32 PM
dtpolk dtpolk is offline
Registered User
 
Join Date: Nov 2017
Posts: 139
Default

On a well built bracing pattern there should be no gaps to fill. Hide glue is commonly used, but it should dry with a slight yellow or beige tint. It looks like some sort of epoxy, but it's not easy to see.
Reply With Quote
Reply

  The Acoustic Guitar Forum > General Acoustic Guitar and Amplification Discussion > Build and Repair

Tags
braces, breedlove, glue, wood glue

Thread Tools





All times are GMT -6. The time now is 03:36 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Copyright ©2000 - 2022, The Acoustic Guitar Forum
vB Ad Management by =RedTyger=