Replace Bridge Caps
April 20, 2010
Back when I removed the old soundboard, I separated the bridges from the soundboard and set them aside. We need to replace the bridge caps. The cap is the top layer of maple in the laminated bridge structure, which supports the strings at the correct height and couples their vibrations to the soundboard. The first step is to remove the old caps. My preferred method is to use planes to remove the old cap wood just down to the glue line. The holes from the old bridge pins will be plugged with hardwood dowel and epoxy.
Here's the bridge, minus caps, attached to the new soundboard after it was installed in the piano. New caps have been fabricated and are ready to be laminated to the top of the bridge root. The blue stuff is masking tape, to catch the glue squeeze-out.
And here's the new caps glued and clamped in place:
The new caps are deliberately made thicker than needed. The correct height is determined by removing wood until the string makes a 1 degree bend as it crosses the bridge.
This process is repeated at approximately 6" intervals over the length of the bridge.
Each gauge point is marked with black magic marker. Then the cap is planed down just until the black marks are gone.
The next task will be to install the bridge pins and notch the cap.