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In case you didn’t know, you can email me with your guitar questions/concerns and I’ll do my best to help you. In some cases, I’ll actually answer your email as an entire blog post. That’s exactly what I’ve done here, so hopefully those of you out there who might have the same question will find the answer you need…
“I have an acoustic guitar and keep breaking brand new strings while I’m getting them tuned up to pitch. It’s always my high B string, and it always seems to break near the tuning peg as I’m tightening it up to pitch. Why does this keep happening?”
Believe me, I know how maddening it can be to break a brand new string during a string change, especially if you don’t have a good supply of single guitar strings available to replace it.
Really, this shouldn’t be happening–certainly not very often. If you find that you’re constantly breaking the same string while tuning, and it’s always at the headstock-end of the guitar, then there’s usually some issue with the tuning post (the post you wind the string onto) or the nut (the bone or plastic piece the strings pass over on their way to the tuning posts).
It can be hard to tell for sure which one it is, because the spring-like action of a string that’s been wound onto a tuning post can make it difficult to tell exactly where the string snapped.
Most Likely Cause: A Sharp Tuning Post
It’s not uncommon for the hole on the tuning post–the metal post you wind your string onto–to have edges that are just sharp enough to cut a string as you tighten the string up to pitch. The thicker wound strings (low E, A, and D) are usually strong enough to resist those sharp edges, but the thinner unwound strings (G, B, and high E) are susceptible to being cut.
These edges can sometimes be sharp enough to cut your strings
This issue can be fixed with careful use of a file to smooth-over the sharp edges. However, I recommend letting a pro do this rather than blindly taking a file to your expensive guitar–unless you’re really comfortable doing this kind of work (or simply don’t care if you screw up).
On the other hand, there’s also a DIY method that doesn’t involve a file. All you need is a piece of guitar string–preferably a thicker, wound string like a low E or A string. We’re going to basically use that piece of string in the same manner we’d use a file–using the winds of the string as little teeth to gently round-off those sharp edges.
Procedure – Using an Old Guitar String as a File
1. OPTIONAL: If you’d like, you can remove all the strings to give yourself more room to work, but it’s not totally necessary. If you do, it’ll give you a sacrificial low E string, which we’ll use for our procedure. That’s what I’ve done for this demo.
2. If you chose to remove all your strings, grab the low E and clip off a straight 6 – 8 inch piece from one end before you throw it away. Otherwise, you can instead use the non-ball end of a new string without actually clipping it off. For my demo here, I removed all the old strings (since they needed to be changed anyway) and clipped off the end of my old low E.
You can clip that curl off the end if you’d like–we’re not going to use it
3. Turn the offending tuning post so that the holes are aligned sideways (not facing the other tuners) so you can get the angle needed to feed the piece of string through easily. In a moment you’ll see why this position is helpful.
Turn the tuning peg until the holes are aligned as shown
4. Thread your piece of string through the tuning peg and grab the other end with your other hand, like you’re holding dental floss and preparing to floss your teeth.
Thread your piece of old E string through the tuning post
Grab the other end with your other hand
5. Bend the string around enough that it curves just enough to contact that sharp edge of the tuning post’s hole. Don’t bend it so much that it creases–you want it to remain rounded so it can slide easily.
You want the string’s windings to contact the sharp edge of the tuning post hole
6. Now, gently pull the string back and forth in a sawing-type of motion, making sure the string’s windings rub against the sharp edge. You’re not trying to remove a large amount of metal here–you only want to gently and very slightly smooth-out whatever sharpness might exist and create a more soft, rounded edge. While you’re at it, you can do the opposite edge too. While in the same rounded position, simply shift the pressure to the edge of the hole on the opposite side.
7. Repeat this procedure for the other edges of this post’s tuning holes, since we’re not sure exactly which edge might be cutting your string during tune-up. Also, more than one edge might be sharp.
8. Carefully blow or dust-off any metal filings that might have fallen onto the headstock.
Once you feel you’ve sufficiently rounded all 4 edges of the tuning post’s hole, cross your fingers and string it up with a new string. Hopefully the new string won’t break now or in the future while you’re tuning it up. If it does, remove the string and repeat the procedure again–rounding those sharp edges just a little more. If the same string continues to break, it’s possible it’s not the tuning post, and the problem might instead have to do with the nut.
Other Possibility: Dirty or Misshapen Nut Slots
A guitar’s nut slots are the #1 thing that get rushed at the factory–especially on low and mid-priced, mass-produced guitars.
Even if your guitar’s nut did get proper TLC before leaving the factory, the bone or plastic it’s made of doesn’t last forever. So, over time normal wear-and-tear can take its toll. The slots can become misshapen and/or become dirty with grit and grime after years of use.
All these factors can lead to string breakage at the nut. Just as sharp tuning posts can act like little string cutters, dirty or misshapen nut slots can break strings too.
There’s no way I’ll be able to cover the topic of nut slot shaping in this blog post. What I can show you, however, is how to clean and lubricate the nut slot. That’s another easy, DIY thing you can do safely, and it just might be all that’s needed to stop those strings from breaking during tuneup (assuming the nut is the culprit).
Procedure: Cleaning & Lubricating Guitar Nut Slots
To clean and polish nut slots, I like to use a small piece of ultra fine sandpaper that is 2000-grit or higher. You can find small batches of these fine grits online or at hobby stores.
I bought this sandpaper kit at my local hobby store for $9, but you can also find it on Amazon here
In this case, I’ll be using 2000 grit from an Alpha Abrasives sandpaper kit I bought at a local hobby store. I like 2000 because it’s abrasive enough to remove dirt and debris from the string slot, but not so abrasive that it’s going to modify the shape or depth of the slot (as long as I’m gentle with it).
Remember, my intention here is to show you how to simply clean out the slot, not physically modify it’s shape.
1. Get a piece of 2000 grit sandpaper, and cut out a very small rectangular piece, as shown here.
Cut a rectangular piece that’s about 1 in. long by 1/2 in. wide
2. Fold the sandpaper in half lengthwise, but don’t put a hard crease in it by pinching the edge flat. Just fold it over and let it crease naturally. You can gently flatten it a bit if it seems too wide for the string slot, but try to avoid creating a sharp crease.
3. Insert your piece of sandpaper into the slot and gently rub forwards and backwards. You can also use a sharp corner to scrape inside the slot too if you feel it’s needed to get out stubborn gunk. Remember, you’re not trying to actually modify the shape of the slot here, so be gentle with your pressure.
Gently move the sandpaper back and forth. You’re just trying to clean, not modify the shape of the nut slot
4. Once you feel you’ve got the slot nice and clean, remove any resulting bone dust or debris that might be inside the slot by blowing it out or sweeping it out using a small paintbrush.
5. Apply a drop of lubricant to the nut slot. My favorite product for this is Big Bends Nut Sauce. I’ve used other products too, including graphite (shaved pencil lead), but none of them have performed quite as well as this stuff. It can be difficult to see the lubricant coming out, so I recommend putting a paper towel next to the slot to catch any excess.
Applying a bit of Big Bends Nut Sauce.
That’s really all there is to it. Now, string it back up and, assuming the nut was the problem and you did a good job cleaning and lubricating it, you shouldn’t have further problems with the string breaking. If you do, it’s possible there’s another problem–such as a misshapen nut slot. In that case, I’d recommend taking it to a pro and they’ll be able to easily reshape that slot so it’s not cutting your string.
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