Warped Bridge Woes...

[Andrew]

Hey guys, Im in the middle of a bridge reglue on a somewhat local (to me) handcrafted acoustic, quite a nice guitar. The guitar had been subjected to some undesirable temperatures at the hands of a previous owner, I suspect, and the bridge began to pull up at the back edge as will happen. Anyway the bridge came off without issue. Upon removal it was obvious that the bridge had cupped across the grain. I tried FFs method of submerging the bridge in boiling water as he described it on FRETS.COM, to no avail. This is the second time Ive tried it and the second time it didnt work for me. So heres my first question: if/when this does not work, what is to be done? Are the only options sanding the bottom flat or replacing the bridge? In this case sanding would be objectionable to me with the amount of cupping that needs to be corrected - the middle of the bridge wings would end up substantially thinner than the edges.

Issue number 2: in attempting to address this cupping I boiled the bridge again then clamped it to a flat piece of wood with cauls on the top that are concave enough so as to press the edges down, hoping to coax it back into shape. I got some minimal results after a couple hours clamped up, so I tried again. Except this time I over did it and clamped to hard, as indicated by a small crack sound. In the following picture you will see a hairline crack running from the bottom treble side of the saddle slot to about halfway out the bridge wing. Is this bridge pooched? Can this crack be glued? Normally I would say no, but this crack still closes up invisibly with very little finger pressure, so I must ask. And even if it can be glued, what then is to be done about the cupping?

Any help would be great, I really wasnt expecting to be making a new bridge here, but if I have to eat my mistake on this one, so be it.

[Mike Kolb]

Paul, do you also lay-in a radius (25' or whatever) to your aluminum block for bridges?

[Paul Breen]

Hi Mike,

No, I use flat stock.

Never felt the need to do this with flat top guitar repair, there is usually some belly bulging from a lifting/ warped bridge that needs flattening anyway. Also, a 6" bridge centered on top of a 25' radius would project out right/left of the center where it touched the arc 3". The resulting distance downward from the bottom of a flat bridge at either end to the arc is .03", why bother?

Maybe David will chime in but i would think that you would also need a radius on your interior clamping caul to get the bridge re-glued effectively with his approach.

[David Farmer]

The 25' radius was to accommodate any kind if spring back. a little "over bend". They come out flat for all intents and purposes.

[Andrew]

And the new bridge. Pretty good if I say so myself. Note the A string pin hole is slightly out of line. Its hard to see on the original, but its there too. It even lines up with the holes in the top!

[Mike Kolb]

Nice job, Andrew :)

[David Farmer]

Looks good Andrew.