Ovation bridge reglue
Here’s the patient; an Ovation D-style guitar, with a lifting bridge.
A quick probe with my bridge removal palette knife shows how far the lifting has spread:
It might be possible to wick a little glue under the gap, and clamp it up, but for the best result that bridge has to come off, and get reglued from scratch. so, out comes the piezo pickup, and the less-than-slick shim somebody has added to raise the action:
Some makers like to bolt their bridges down - so it’s always worth a peek into the soundhole to see what those pearl dots on the bridge might be hiding:
To protect the top I make up a heat shield from cardboard and aluminium foil. It wouldn’t cut the mustard for Space shuttle re-entry, but it’s more than enough to keep the top from getting too hot whilst I heat up the bridge.
After a very short session of heating the pearl dots get loose enough to pop out with a craft knife, exposing the slotted machine screws which clamp the bridge down. This was a bit of a bonus bonus, I expected to have to drill the pearl dots out and replace them with new.
With the bolts removed, I refit the heat shield and alternate between heating the bridge (using a clothing iron retired from active service) and working the bridge knife under the bridge very slowly. Finally it comes loose:
You can see exactly why the bridge began to lift - the factory scraped the poly finish back to glue, but stopped at least 1/4″ in from the edges, plus they applied finish to the bottom of the bridge too!
**Edit** - Apparantly this can’t be laid at Ovation’s door. Ovation glue their bridges directly to the finish using gel CA, so this is likely a previous repair which has failed.
As if that wasn’t bad enough, the poly finish is so thick that their crude attempt at scraping it back left a massive void under the bridge, which was filled with *horrible* snotty glue.
The glue is pretty easy to clean off the bridge with a sharp chisel. It’s a good deal tougher to scrape off the top, but a hot bridge removal knife peeled it away pretty cleanly. The glue here is ridiculously thick - It’s hard to read the caliper display, but it’s reading 1.18mm!
With the worst of the glue was gone, I start to prepare a clamping caul. I tape a sheet pf paper over the top, and trace the shape of the bridge onto it.
Then, I use a pair of ceramic magnets and a pencil (from an old electric toothbrush head) to trace the bracing onto the top. I mark three points on each brace, then join the dots so I’ll know where to notch my clamping caul:
Next, I turn my attention back to preparing the top. Those deep gouges need to be filled if any repair is going to last, so I carefully mask around the bridge, and start routing the area within the bridge to level it all out.
I prepare a filler piece, using walnut constructional veneer, which is 1.5mm thick. I scribe around the edges, marking the shape on the guitar top, so I can create an accurate cavity for the patch. There are still a few small low spots, but I happy that I’ve made a good compromise between getting a clean glueing surface, and not going too deep into the top.
The clamping caul is fitted in through the sound hole, and the patch is clamped in place. I glued it with slow cure epoxy, and lined the top clamping caul with brown parcel tape to prevent it getting stuck to the guitar.
Then, I begin the slow process of scraping the patch flush with the top. As the patch comes level with the top, I start scraping the finish within the bridge footprint too. I can’t remove it totally, but I can at least ‘key’ it a bit. I stay about 1mm inside the lines to ensure no scraping is visible once the bridge is in place.
Since I’ll be glueing the bridge on with epoxy, I use the tip of a file to roughen the patch and surounding finish. This will give a bit more ‘tooth’ for the glue to epoxy to grip. Since epoxy is an adhesive rather than a glue, a little roughness is beneficial, whereas a glue is best used with perfectly smooth, flat, gluing surfaces.
Nuts - my only ‘after’ picture is blurry! After prepping the glueing surfaces I applied epoxy to both pieces, and allowed it a few minutes to penetrate. I applied a second batch to the guitar top, and then clamped the bridge in place. Any squeezeout was caught by the masking tape, and smoothed away with a rag dipped in meths. After curing for 24 hours I removed the clamps. redrilled the holes for the piezo pickup, and re-installed it. I strung the guitar up (without replacing the shims I removed - god only knows why they were fitted - the action was fine without them), and it was returned to the owner before I got any decent photos.