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Ed's Shed: How to Adjust Your Guitar's Truss Rod

My last column generated so many replies that I’ve decided to take a brief step away from nut problems to delve deeper into the question of adjusting the straightness of your guitar’s neck.

Here’s the thing: If your guitar’s neck is not adjusted correctly, then all your hard work repairing the top nut slots, not to mention setting the action and intonation, will be a big old waste of time.

Adjusting the truss rod can be a scary thought if you've never done it, but take it slowly and it's a key ingredient to making your guitar play its best.

Check out my last column to find out how to check the straightness of the neck. If the neck is bent, you need to adjust the truss rod. The only visible part of this metal rod is the bolt in a hole, or under the plastic plate (See photo 1 in the photo gallery below), next to the top nut on the headstock.

On old-school Fender guitars, there’s a crosshead bolt at the body end of the neck (See photo 2) that's dealt with using a screwdriver. You generally have to remove the neck to access this bolt (email me if you need advice on this: Gibson guitars have a nut that is adjusted with a box wrench. Most modern guitars have an Allen bolt that is adjusted with, you guessed it, an Allen wrench or key.

When you’re adjusting the truss rod, make sure the Allen key is seated properly in the truss rod nut; push it all the way in (See photo 3). If you don’t, the nut can be damaged when you try to turn the wrench. The same is true of Fender- and Gibson-style truss rod bolts. They can be easily chewed up by careless tools (in both senses of that term).

Always treat the truss rod with respect. If you turn it too far, it can snap, and that’s a damn expensive repair. You will cry. So always make small adjustments and constantly check your progress. If it feels too tight to adjust, don’t force it. Contact me and I’ll tell you what to do next.

If, when you’ve eyeballed the neck, it’s "over-bent" (higher in the middle than it is at the headstock and body ends) adjust the truss rod key, wrench or screwdriver, anti-clockwise. If the neck is "dipped" (lower in the middle of the fingerboard than at either end), increase the tension on the truss rod by using your tool to adjust it clockwise.

The idea is to get the neck straight as opposed to a banana shape. That doesn’t always mean dead straight. Guitars often play at their best with some relief — a slight dip. So you might have to experiment a bit to find the sweet spot where the action feels just right. I’ll go into this in a bit more depth when we get into adjusting the action (or string height) in a future blog post.

Again, in the meantime, email me if you need advice. Next time, I’ll get back on track with the nut job. I’ll show you how to select the right superglue to use for the repair of those pesky top nut slots. Bet you didn’t realize that there are different "viscosities" (try saying that when you’re drunk) of superglue.

Intrigued? Tune in next time then!

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