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Old 07-05-2019, 12:33 PM
Alan Carruth Alan Carruth is offline
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Join Date: Feb 2011
Posts: 3,311

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.
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