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Oahu Guitar Restoration #5: An Adventure with the Bridge Plate!

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Blog entry by Lemongrasspicker posted 04-07-2017 02:29 AM 694 reads 0 times favorited 0 comments Add to Favorites Watch
« Part 4: Crack Repairs and Top Reinforcement Part 5 of Oahu Guitar Restoration series no next part

If you prefer not to read the video is here
https://www.youtube.com/watch?v=lwLDBA1nQIo

So we are now at the most annoying part of this entire restoration and that’s the bridge plate.

Here’s a picture so you can get an idea of what and where the bridge plate is. It’s the small overlaid piece of wood

A guitar’s bridge plate does quite a few very important jobs for the guitar. To make it simple, the pull of the strings on the top of the guitar is quite intense, and it’s continuously pulling as well. The tension is around 150-170lbs of pressure. That’s alot to ask of a long thin piece of spruce to hold up to! The bridge plate works in the same fashion as a lamination in any other application.

The lamination effect in this case is to help stiffen the top of the guitar against the constant pull of the strings. Keep in mind that there are guitars out there without bridge plates (classical/nylon string guitars are a good example) that function perfectly well. It’s a method of building that works very effectively.

The bridge plate on this guitar had many issues. It was in the wrong position, they used a poor material, and the grain runout was extremely bad, meaning that this guitar’s top had it been strung to full tension would’ve warped beyond repair in a few short years. Thankfully it looks like this guitar had been only strung for a very short while. In my mind it plays out in a way that would look like this. Guitar was purchased, played for a few months, they broke a string/lose interest, put it in the closet, and let it sit for the many decades until it came into my possession.

To remove a bridge plate on a guitar is a highly invasive and challenging repair on ANY guitar, having the back off makes it easier but having done this on multiple instruments, it’s always a little challenging just due to the nature of the construction.

I made some missteps in accomplishing this task, the first of which was not using heat sooner and assuming that the glue was in the same state as the rest of the guitar (dry and crumbly) not the case with the bridge plate, that sucker was on there! Of all the things they glued well, this was the one.

The original plate being in the wrong spot would’ve caused a “pivot” point in the top. This happens because where the lamination stops was right at the edge of the bridge where the highest amount of tension would be when tuned to pitch. The new bridge plate extends past the edge of the bridge which helps to flatten the top and also serves to help “disperse” the tension of the strings across the top.

I used my knife, a file, and my wooden plane (really starting to love wooden planes over their metal counterparts for some reason) to make the new bridge plate, it took a while to make it the proper thickness and width, but I’m pretty happy with it.

Anyways, fun project and now that the new bridge plate is a stronger material, is larger, and is in a better position further behind the bridge, the guitar has a much higher survival rate and will last many more years than if I had kept it original (which I’m sure will annoy some “vintage” guru, but hey, I’m having fun, and if you can’t have fun then what’s the point?)

A picture of the completed new bridge plate. Hard maple is what I used, notice that I extended the size past the lines where the old bridge plate was. I also added some more reinforcement around the soundhole, just for good measure. The guitar doesn’t vibrate hardly at all in this area and so the extra stiffness won’t hurt anything.

Thanks for reading/watching!

Part 5 Thumbnail pic

-- www.youtube.com/lemongrasspicker



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