Fixing a Tune-O-Matic that won't tune

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Issue 228 October 23, 2014

This bridge is in the wrong spot, so the guitar can’t play in tune. Rather than drill new holes in a vintage guitar body, Dan Erlewine comes up with a clever solution.

About the guitar in this video: This is a Gibson ES-330 with one owner. He bought it new back in 1964 when he was a just kid.

In this Trade Secrets video:
  • Unusual misplaced factory bridge
  • Dan shows how to establish that it’s in the wrong spot
  • Solution one: Dan turns brass parts on his lathe
  • Solution two: how to do the same thing without a lathe

Video Transcription

[on-screen text reads: Trade Secrets! Relocating a Tune-O-Matic bridge. Dan Erlewine Stewart-MacDonald]

The Tune-O-Medic Bridge Jack

Dan Erlewine: Here's a cool tip for working with the tunamatic bridges that won't tune. My friend, John Sol, bought this guitar with his dad in New York City at Sam Ash Music in 1964, that's the year it was made, and played it in college, but he hasn't played it for years. And it's here for a setup. The strings are laying right on the frets, and I'm going to raise it up at the bridge, real easy with this bridge jack [on-screen text reads: Tune-O-Medic Bridge Jack]. This is a tool that I saw used at Gibson when I visited the factory often during my band days in the sixties. [on-screen text reads: Tune-O-Medic Tool Kit] I always remembered that tool, then years later, we made it here at StewMac.

How to determine the bridge is in the wrong spot

Dan Erlewine: Whoa, that's out of tune, man. If it's out of tune, the first thing I'm going to do is run a Straightedge down the center of the neck and put a piece of tape in the area of the 12th fret. And you're going to mark on that with the pencil, the center of the 12th, that's your scale length, and then about nine 64ths more than that for compensation. And that's an important mark, because when you move that down to the bridge, the second mark should be in the center of the bridge area, approximately, not that. So this bridge is way too far forward, at least that much if not more. There's no way it's going to play in tune without this fix.

Solution one: Making brass posts on a lathe

Dan Erlewine: So what I'm showing you here, is we want to move the post back about three 16ths, and then it'll play in tune. For many years, I've plugged these holes with the birch dowel or a maple dowel, put some cherry red on it, and re-drill the posts. And that's a good fix, and I could do it now, but with the vintage guitar market the way it is, this guitar's worth a lot of money, and it's mint. So what I came up with is this. I made these little posts on my lathe. It's an offset thumb wheel, that's a post that slides into the hole, and in the center is the post moved back three 16ths of an inch.

Dan Erlewine: With a pair of these on here, this guitar will play in tune. And if John ever wants to go back playing out of tune, he can still put the original parts back on. And you don't need a metal lathe to do this. You can do it like this, and I'll show you.

Solution two: Making posts without a lathe

I drilled a hole, it was about 110 thousandths through the side of a thumb wheel, three 16ths off center. And it just happened to be the right size for this pickup screw. And then the screw kind of cut its own thread, and that becomes my post. I'm going to cut that off with a hacksaw and be in business.

Dan Erlewine: Clean up any burrs, screw it down in there tight. Then I'd take it off and put some JB weld on it and make that permanent, it's epoxy with metal in it. Put some JB weld on your 6/32 post, and you have the same thing I made right there in your shop. Now I'm going to take them both out and just clean off the dirt with a little preservation polish, and we can install this bridge and see if it plays in tune.

These are old strings, and it's right in there. I know it's going to work perfectly once I get the action where I want it. And I have to shorten these posts, they're too tall, they're stock posts. Hey, John, you're going to love this. If you don't, I'll keep it.

[on-screen text reads: Stewart-MacDonald. Guitar tools, parts, supplies.]



Dan Erlewine

Guitar Repairman and Builder

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