4 - Fixing the bridge
Now for gluing the bridge back on. I decided to make a bridge clamping caul, because it’s tricky to make bridge clamps hold position on scalloped braces. I held a sheet of white paper against the bridge plate with my fingers and used my thumbnail to push the paper into the corners of the brace/bridge plate intersection to mark the area.
You can mark the front and back edges of the bridge plate the same way, and when you remove the paper the crease lines will provide a reasonably accurate template for your clamping block. Next, transfer the template to a piece of scrap MDF and cut it to size, then cut another piece, slightly wider, to overhang the X braces each side of the bridge plate. Then I attached cork pads to the overhangs to protect the braces and drilled two 10mm holes for the outer bridge pins.
Since the original bridge outline was clearly visible, I placed the bridge in position and marked the position of the outer pin holes on our freshly sanded gluing surface. I then drilled through the spruce patches and increased the diameter to accommodate the bridge pins
using a reamer.
The beauty of doing a bridge refit, as opposed to a first-time bridge fit, is that you can use the existing bridge pin holes to position the bridge and stop it sliding around when it has been glued (of course this assumes that the bridge was correctly positioned in the first place). Just make sure you use plastic pins, because wooden pins will stick to the wood glue – and if that happens you’ll be in real trouble.
Another spruce off-cut was placed on top of the bridge along with two more holes for the bridge pins. This was done for protection and to distribute the clamping pressure across the bridge. So-called ‘pyramid’ bridges like this one are tricky to clamp because of those pointy bits on the top, so I stuck some cork pads onto the ends to make life easier.
Before clamping I thoroughly scraped and cleaned the bridge base to remove all traces of glue and old finish. This revealed that the ebony had been dyed black because the natural timber had so much brown colouring. The rough-looking visible surfaces were sanded with 320 grit paper followed by micromesh and, after masking off the underside of the bridge, I gave it a final buff up with black shoe polish.
The clamping caul was covered in plastic packing tape and secured to the bridge plate using two very small pieces of double-sided tape for easy removal. The bridge was positioned using the pins and clamped using three bridge clamps. The glue squeeze out was cleaned up immediately with a damp cloth and the guitar was set aside for 24 hours before the clamps were removed.
4. Acoustic Rescue