Bridge plate question

[Fatstrat]

I'm interested in DIY learning basic acoustic guitar repair. And in search of repairable candidates have run across several Epiphone Pro-1 guitars with broken bridges at attractive prices. On these guitars, the string end are "top loaded". Like on Classical guitars. And do not run through the bridge into the body. Apparently this isn't a very good system for steel string guitars because the bridges are splitting in half. With the rear portion were the strings ends go through breaking off. It would seem that maybe the best fix might be to replace the bridge with a traditional string through the top bridge. But I'm wondering if these guitars have an inside the body bridge plate? Which would seem to me to be necessary for this type of fix. Would it be feasible to add one?

[murrmac123]

The problem with the Pro-1's is that they were designed originally for extra light strings , like .009 - .047 so when people put light or medium strings on, the pinless bridges shear at the back die to the extra tension.

Whether the guitar would need a bridgeplate from the point of view of structural stability (if you fitted a pinned bridge) is a matter of opinion ... some will say yea and some will say nay. What is certain is that you would have to fit some kind of plate to prevent the ball-ends from pulling through the top (which is a laminated top btw).

I would try gluing on a piece of vertical grade HPL (Formica) on the underside of the top, below the bridge, this will resist the pull of the ball ends adequately without having to resort to fitting a maple or a rosewood plate (assuming that there is no plate there in the first place).

[redir]

I am not familiar with the guitar but it very well may have some sort of bridge plate there even though it's a pinless bridge. If not I'd just get a piece of hardwood like maple and fit one in if you want to go with a pinned bridge.

But I disagree on the pinless bridge weakness argument. When done right they make a very good bridge system. The problem more than likely with a cheap guitar like that is that they glued the wooden bridge right on to the finish and it let go under the front of the bridge while the back edge of the bridge held fast and as such it was pulled apart. Seen that happen many many times.

[Fatstrat]

THANK YOU! Very helpful and encouraging responses. There are several of these guitars available to me. And they would be great practice at installing a new bridge.

[Howard Klepper]

What I can see as the design flaw on those Epis is that they cut a major stress riser (a deep straight-sided groove) right in front of the block that holds the string ends, and ran that stress riser almost all the way across the bridge, right where the wide part of the bridge meets the belly. The failure of the bridge along that line was predictable.

IMO the bridge plate on a steel string guitar does more than keep the ball ends from digging into the top. It also stiffens and strengthens the top where it receives the pull of the strings. If made wider than the bridge (as I do with a 1/8" wide bevel on the plate above and below the bridge) it spreads the stress of string pull over a broader area. But some builders make the plate the exact same width as the bridge and it does OK for them.

[murrmac123]

Originally Posted by Howard Klepper

IMO the bridge plate on a steel string guitar does more than keep the ball ends from digging into the top. It also stiffens and strengthens the top where it receives the pull of the strings.

Indeed, Howard . My pondering above was more about this particular top, which is, to put it bluntly, plywood. I thought it might be possible that adding more mass to the bridge area might be detrimental to the tone, such as it is, and that the plywood might not require the same level of reinforcement deemed necessary for a solid spruce top.

[mirwa]

Originally Posted by Fatstrat

have run across several Epiphone Pro-1 guitars with broken bridges at attractive prices. On these guitars, the string end are "top loaded". Like on Classical guitars. And do not run through the bridge into the body.

I am very familiar with these guitars. (Epiphone Repair Warranty Agent)

They do not have a bridge plate installed underneath, you can install one quite easily.


Steve

[mirwa]

Double.....

[Fatstrat]

Thanks again. I did purchased one of these guitars and intend to attempt a pinned bridge installation. BTW, I got a solid top Pro-1 Ultra.

[Fatstrat]

Another question. Is Elmers wood glue suitable for a bridge replacement? I ask because that's what I have on hand. But I am willing to buy a better glue if need be. Thanks.

[redir]

If it's the yellow Elmer's Carpenters glue then yes.

[Fatstrat]

As it turns out, at least on the solid top Pro-1 Ultra model, these guitars do have a factory bridge plate. Which makes my repair much easier.

[mirwa]

Unusual, I haven't found that before, I wonder if it's factory fitted.

Steve

[Fatstrat]

Originally Posted by mirwa

Unusual, I haven't found that before, I wonder if it's factory fitted.

Steve

It appears so. My guess is that as the Ultra model is an acoustic/electric, perhaps it was added as a point to attach the pickup? The electronics were stripped from the one I have. But there was something that resembled playdough stuck to the bridge plate. I assume for attaching the pickup?

[Fatstrat]

Moving on to next phase. I've spent the past 2 weeks gathering needed parts and tools. (mostly waiting for them to arrive in mail) And approaching time to use them.
My question now is your opinion of if it is better to attach the new bridge first, then drill/taper the holes in the top? Or drill/taper, then attach bridge?
I've searched the internet and it appears my project may be a bit unique in that I haven't been able to find any references to someone adding a pinned bridge to a guitar that previously had an unpinned bridge.
Any advice appreciated.