Stay in tune
By luthier Patrick Podpadec
Were back again! I’ve been busy again the past few weeks with a variety of different repairs. One was removing a bridge from an older Martin guitar. Someone had tried to lower the action by removing wood from the top of the bridge so that the saddle would protrude up higher out of the slot so that there would be some break angle on the strings where they enter the holes for the bridge pins. You need this angle for the pressure that is needed so that the strings don’t slide around and your guitar does not sound all “flappy” and such.
By doing this all your doing is causing more problems and destroying the bridge. So to remove the bridge I placed an iron directly on top of it to heat it up. I wasn’t worried about scorching the wood because I had to build a new bridge anyway. I’m careful not to over heat it because I don’t want to cause any damage to the surrounding finish and also loosen any structural braces that are directly underneath that area of the top.
After about ten minutes of monitering the heat I place a small thin spatula type knive between the bridge and the iron for just a few minutes to heat it up some to. I then carefully start to work it under a corner of the bridge .It takes a little patience but with the right amount of heat you can usually wiggle a little and maybe stop to apply some more heat and gently work your way under the bridge. It is important to not that you don’t want to dig into the fibers of the soft spruce wood under the hardwood bridge. ( in this case it happen to be Brazilian rosewood).I was able to successfully remove the old bridge with just a small sliver of spruce that splintered off during the removal. I was able to slice it off the bridge and glue it right back down in its’ proper place.
The next step is to replace the bridge with similar wood as to keep up its’ historical value. I might not be so picky if it were a garage sale special, but being that it was a “51 Martin” I decided to replace it with some special stock of Brazilian rosewood that I’ve been saving for just such an occasion. What I did so that I could guarantee that the new bridge was exactly like the old one was to lightly glue the old one down to a blank piece of wood and drill down through the holes with a 3/16th drill bit all the way through the new blank assuring that the string spacing will be the same as the old one. I then copied the shape by cutting the majority of it on my band saw and the remainder was cleaned up with my belt sander. I then separate the old bridge from the blank and begin to contour the top of the bridge to match the old. This takes time and patience and a good eye for detail. You want it to look like a Martin Bridge. There are very slight variations in contour and its’ important to get it right .
I then get the top ready for glueing the bridge back down. I always scrape down the rough area where the bridge was attached. I use a very sharp ¾’ chisel to do this. Being careful not to scrape outside of the glue line. After this is cleaned up I check to make sure that everything lines up the way it is supposed to.You have to be very careful not to “shift” the bridge when you glue it back down. There are many different clamping methods that I have used in the past to ensure the bridge gets properly glued. Over the years I’ve been able to work it down to just three clamps. This enables me to easily remove any excess glue that seeps out while pressure is being applied. There could easily be a whole article on the clamping procedure alone , but we will save that for a future reading. Thanks so much for your time and please “Stay in Tune”
Patrick from Wood-n-Strings