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Replacing the bridge on an acoustic bass
- Thread starter domportera
- Start date
Hopkins
Commercial User
My Breedlove acoustic bridge is like this, but its a solid spruce top not plywood laminate. If done correctly the bridge design is fine. But not on a plywood top.
Yes, but the glue bond between the bridge and top is not what supports the string tension. The strings are typically anchored on the bridge plate below the top.
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Steel string acoustic guitars use through hole string mounting, with the strings anchored below the bridge plate. Bridge pins keep the ball end of the string securely in position against the bottom of the bridge plate.
Steel string acoustic bass guitars may use top mounting as the heavier strings don't yield as well to the break angles required with through hole mounting. In this case bolts are used to withstand the string tension.
The plywood top itself is not the cause of failure. Many lower cost guitars had plywood tops, including some of Martin's Sigma models.
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Steel string acoustic bass guitars may use top mounting as the heavier strings don't yield as well to the break angles required with through hole mounting. In this case bolts are used to withstand the string tension.
The plywood top itself is not the cause of failure. Many lower cost guitars had plywood tops, including some of Martin's Sigma models.
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Turnaround
Commercial User
Turnaround
Commercial User
No kidding! 6 bass strings of tension onto a piece with nothing but a glue joint for security? And it's not even the bridge-to-top glue joint, but the glue in the plywood layers as well. Wow.
And did I mention - wow?!
There were two small screws in there - look close. They both broke. Not surprising, they almost look like an afterthought.
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Do you guys think it would make sense to reinforce the bridge of my new one by drilling some longer screws into it from the outside? Or in any other way?
IANAL, but no. Screws are almost always the wrong fastener to use. I wouldn't add any metal to an acoustic instrument beyond new strings.
Hopkins
Commercial User
My guess is, there is no bridge plate on the underside of that top.
Maybe not, but a bridge plate wouldn't have kept it from happening.
We used to get almost ready to fly r/c airplanes from China and the first order of business was to re glue all existing glue joints possible. Glue was spotty and inconsistent and just enough to keep the structure from warping when the covering was shrunk into pace. Fine for shipping and assembly by the buyer, but stress it just a tad and it would fold like a cheap suit. The fix was tedious but simple, get a bottle of thin CA and a long capillary tube and get busy. I'm pretty sure the top in the picture is plywood and I've seen plywood from china that looks like several thick layers of veneer bonded with laundry starch. Not trying to knock anything here, just relating some of my personal experience with Chinese wood products.
That said, I've seen some of the hands down best prebuilt r/c airplanes in the business, also made in China, often from the same manufacturer who produced the marginal potential kindling and called it a model airplane. They would be marketed under different names of course, and most of the really good stuff was usually private label built to the personal specs of the US or European importer. They are capable of building to as high (or low) a level of quality as you are willing to pay for. In short, their low cost stuff is low cost crap for the most part, but if you are wiling to pay a reasonable price you can get a lot of bang for your buck.
That said, I've seen some of the hands down best prebuilt r/c airplanes in the business, also made in China, often from the same manufacturer who produced the marginal potential kindling and called it a model airplane. They would be marketed under different names of course, and most of the really good stuff was usually private label built to the personal specs of the US or European importer. They are capable of building to as high (or low) a level of quality as you are willing to pay for. In short, their low cost stuff is low cost crap for the most part, but if you are wiling to pay a reasonable price you can get a lot of bang for your buck.
When that replacement instrument arrives, it is likely to develop the same problem. Might be worth a shot to add a wood plate under the bridge inside the body, then drill through the bridge and screw the bridge down to the additional plate. Not a nice thing to do to an instrument, but this is never going to be much other than a practice piece...and that just might keep it stuck together.
no, because chances are the replacement will have the bridge in the wrong place just like the first one did!
remember your initial problem, that it was all out of tune?
your best bet is to get your money back entirely and don't buy that brand anymore.
Note that the top failed. There's still plies glued to the bridge.
I'm in the, "Not another of this brand", camp.
I'm in the, "Not another of this brand", camp.
Plywood with inadequate glue (either formulation or application) between the veneers will guarantee failure.
A donkey dies a donkey. It doesn't die a horse.
Find something else.
A donkey dies a donkey. It doesn't die a horse.
Find something else.
You're good dude. Get a steel plate at least 1/8 inch thick and put it under the body. Don't use the wood screws that come with the body, use machine screws instead. Feed them into the bridge, body, plate, and hex nut them at the end. The plate will redistribute the weight enough to put on an adjustable steel bridge. And to all who disagree, I've done this no problem multiple times. I am an experienced luthier and I say go for it 
