Bridge gluing before or after finishing

[Jack Mayer]

Greetings from South Central Penna., first time poster here and I hope I'm doing this right. I'm finishing my first guitar and I'm having some confusion regarding gluing the bridge to the top and was hoping for some guidance. Martin finishes the whole body then hogs the finish off with a router, under sizing the glue surface so the bridge overlaps the finish making a clean appearance. My concern is the lack of a good wood to wood glue joint since the glue joint would be the thickness of the finish. Where as, David R. Young cuts a tape patch the shape of the bridge, tapes it in the appropriate location, finishes the guitar, removes the tape and then glues the bridge with good wood to wood contact. I'm thinking Mr. Young's technique would need some finish touching up though. Any thoughts would be greatly appreciated, thanks.

[ken cierp]

Hi Jack -- welcome!

Got to love CNC machines -- we have three and I am still amazed at their capabilities. But the good news is that the computer aided surface prep is a very new innovation at the Martin factory and they in fact used a mask for many decades. That's the way I've been doing it for years too, with no problems.

A couple of tips -- make the mask a tiny bit undersize, make sure you have very sharp tools for making the mask as well as removing the mask after finishing, knock down the ridge that will be left in the finish coats and lastly sand a very tiny bevel on the perimeter of the bridge glue surface. Also make sure the bridge glue surface matches the sound board contour. --- Here's some visuals

http://kennethmichaelguitars.com/bridgemask.html

http://kennethmichaelguitars.com/bridgeprep.html

[Jack Mayer]

Fantastic. Thanks Ken, makes perfect sense. What would you recommend the best way to knock down that ridge/edge of finish after the patch is lifted?

[ken cierp]

Single edge razor blade -- knock off the corners, it can then be used as a very effective scraper.