Magnatone Giveawya

September 2014
more... GearHow-TosJuly 2008

New Sound, Old Guitar

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I eventually felt like the above mentioned screw-it-down method would stiffen the top in a critical area of the bridge, giving me some reservations. I also had second thoughts about trying to countersink the all-thread under my new bridge and into the top at just the right point, and again into my “Double Bridge Doctor” at just the right point. I shaped my bridge plate and two new braces while pondering this Bridge Doctor point, and then arranged the new plate, braces and bridge [Photo 6]. I then glued the new bridge plate under the top after much sanding and re-fitting inside the soundhole. I wanted the plane to be uniform so that when I glued my braces in place they would fit snugly. I used 5 Minute Epoxy for this process so I could hold the pieces in place until they set, negating the need for clamps.

This was make-or-break time. The old bridge had to come off and the new one had to go on. For this process I elected to go to another local repairman, Steve Hickerson at Tulsa Guitar and Electronics. He had a special malleable heat iron used to slowly heat the old bridge from side to side while gently wedging a piece of wood under it.

It was finally time to put my new bridge on the top. I began by reinstalling the old adjustable bridge saddle, which just happened to line up my new bridge. Once the new bridge was in place, I outlined the contour of the new footprint with a sharp scribe. A Q-tip and some acetone helped to soften the finish under the new bridge pattern; I then scraped the old lacquer off with a small chisel [Photo 7]. This took about an hour and a half.

New Sound, Old Guitar
Photo 7: The top with the bridge removed
After the top had dried thoroughly, I placed my new bridge over the original ebony saddle for alignment – it was then taped down until it didn’t shift. Next, I drilled the new bridge pin holes in the top [Photo 8]. Once I recovered from the trauma of drilling 12 holes in the top of a near mint Gibson B-45 12 it was time to glue the new bridge in place. I had special ordered some rosewood bridge pins with mother of pearl dots from DLE Manufacturers Representatives, Inc. in Fairfield, California, and had them on hand for the occasion. I selected my six favorite pins and put one layer of tight masking tape around each one to keep them from being inadvertently glued to my top or the new bridge.

New Sound, Old Guitar
Photo 8: The top with new bridge pin holes drilled
Next, I used blue auto masking tape to form a perimeter around my scribe marks on the guitar top and masked the top with plain masking tape to keep the epoxy off the original finish. I again mixed up some 5 Minute Epoxy, and used a toothpick to evenly cover the bottom of the new bridge. I quickly set the bridge in place and inserted the six pins into random holes to secure and align it. I pushed down on all the points of the bridge that I could and waited for the longest ten minutes of my life. I then let go but felt guilty about it for hours. I removed the bridge pins after an hour and waited overnight before doing anything else.

The next day I began fitting the bridge pins into their new digs. I found that I needed a larger hole that would allow my pins to seat with the strings in place. My #7 drill bit was a touch small, but the next size up was too big. I went to my local hardware shop and discovered that I needed a special drill bit – they had it stashed upstairs, as it was evidently not for regular public use. The new drill bit proved to be perfect and I was able to fit all the pins and strings in place. For the first time I was able to hear the new guitar. It opened up, sounding 30-40 percent louder and richer.


Compensations
It was time to tackle the last obstacle of the project; the bone bridge needed to be compensated so all of the strings would stay tuned in unison as it is played up the fretboard, to the 12th fret and hopefully beyond.

For this step, the bone saddle was put in place and the strings were tensioned one at a time. I decided to use a trick from Don Teter’s book; a round toothpick is inserted under the string at the middle of the bridge and the string is brought to pitch. Then the octave harmonic is plucked above the 12th fret and compared with the fretted 12th fret pitch. If the fretted note is sharper than the harmonic the toothpick is moved back toward the butt or bottom of the instrument slowly and the harmonic is again compared with the sound from the fretted 12th fret. Once the pitches are the same, a line is scribed with a sharp pencil lead on either side of the toothpick. Once this process has been completed for all the strings, the bridge is colored in dark with the pencil to differentiate which areas are to be filed and which are left alone. A red dot was placed to the right of my intonation line, just in case the line was accidentally filed off. A set of fine jeweler’s files works well for this process [Photo 9].

New Sound, Old Guitar
Photo 9: Using red dots to mark the intonation lines on the saddle
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