That’s an easy one: they’re probably getting most of them for free to start with. And on top of that, they have plenty of money AND their own guitar technicians. But can you too, and how? Let me reassure you. By the end of this post you’ll already have a lot less to worry about. By the end of next month’s, you’ll be armed even more.

Whether you’re buying a new guitar or a used one: the principles are the same. All you need are a couple of tools, and the guts to ask the seller some unexpected questions. Now you can do THAT, right?

Wait a minute, are you buying online? Really? Then better make sure you can return that guitar for free, because obviously you won’t be able to do any testing beforehand. Frankly, I’d avoid online instrument purchases: sending crappy axes back and forth just increases global warming. So do it only when it’s impossible to buy that particular guitar or bass in a store nearby, or if it’s really A LOT cheaper online.

You’ll remember from last month’s article that most guitars in shops are poorly set up (and I’m sure you’ve actually experienced that as well). So picture yourself, holding this great-looking guitar, but oh my goodness it’s hard to play, it won’t stay tuned, and you’re hearing really awkward overtones when playing the bass strings beyond the 12th fret. If you don’t know how to judge the true potential of this guitar, these are your options:

  • Put it back on the wall, and probably be frustrated and unhappy for days
  • Buy it anyway, and risk being frustrated and unhappy for a long time afterwards.

But wouldn’t it be great if you had yet ANOTHER option? What if you were able to judge that guitar with more knowledge and confidence? Wouldn’t you like to better UNDERSTAND GUITARS? I guess you do. That’s why you’re reading these articles.

A word of caution, though (yes, that’s a DISCLAIMER coming up).

Sometimes instruments have hidden defects that won’t surface until it’s too late. Sometimes even the pros get fooled (damn’). And I can’t turn you into a professional technician with just a couple of articles, can I? So there WILL still be risks. But together we can minimize them as much as possible. It’s better to know a lot than to know a little, or to know nothing at all (I’m sure we can all agree upon that). So here we go. Please join me.


The neck is the backbone of your guitar…


That’s including the truss rod, of course. The whole should be strong enough, and flexible enough. Needless to say: it mustn’t be deformed, twisted, warped. These few sentences pretty much say it all. And here’s how to check.

Marcus sights a guitar neck

Marcus sights a guitar neck

First of all, you need to sight the neck. This means: inspect it, using nothing but your eyes. It’s not too hard, but you need to get the hang of it. With two hands, palms facing up, hold the instrument up in front of your face. Imagine the guitar is this giant French bread, and you’re ready to take a bite!
(Preferably, have the neck facing away from you instead of towards you. You can do it the other way around, too – both ways will work. I just like the extra distance between my eyes and the neck. It gives me better focus.)

Position the tip of your nose just below the top of the body. This way you can peer alongside the neck. Move the guitar, so you can alternately sight the bass and treble sides. Change your focus: inspect the fret tops, the fret edges, the edges of the fretboard. Practice this, with as many guitars as possible. Soon, you’ll start seeing the details:


  • Is the neck straight or bowed? And is it bowed towards you (“upbow”) or away from you (“backbow”)?
    (It should have a slight upbow – I’ll explain why in a later article – but don’t worry just yet if it hasn’t. Most of the time this is adjustable.)
  • Is the neck warped? You can check this by looking at the headstock. If you hold the guitar aflat, the face of the headstock should be horizontal too (front and back ends of the neck need to be in parallel).
    If this is not the case, DON’T BUY THIS GUITAR!!! A corkscrew-like neck is virtually beyond repair.
  • Looking at the wood itself, do the sides of the neck follow a straight line or do they drift inward and outward? Such drifting isn’t a critical error, but it may tell you something about the general care that was taken in building this particular guitar.
  • Looking at the fret edges this time, are any of them sticking out sideways? Don’t worry, they can be filed back so they’re flush to the wood, but again this reveals a lot about the workmanship.
  • Apart from upbow or backbow: do all fret tops seem to be equally high? If some of them are protruding, you could be faced with loose frets (that need to be glued in) or high frets (that need to be leveled). This means you’ll have to spend extra.


Okay, from here on we’ll start using tools. First of all: unless you have three hands, be sure to bring your capo! (Yes, Flemish readers should bring a capo too). If you’re a bass player and have no need for a capo, try to borrow one from a guitar playing friend.

Take the bass or guitar you’re interested in and sit down in playing position. Pick a spot with as much light as possible. If you know the store to have poor lighting (some do this on purpose to mask small defects, you know!), bring a torch (“zaklamp”) or a smartphone with a torch app installed. If so, bring a friend to hold that for you (unless you want to clench it with your teeth, or unless you DO have three hands).

Capo exactly on 1st fret

Capo exactly on 1st fret

Now tune the instrument, and then place the capo on the 1st fret: not in front of it, but really spot-on. (Again, I’ll explain why in a later blog post. You don’t need to know just yet.)
Make sure the thickest string is making solid contact with the fret. Now press down this string past the 12th fret. Use your right hand to do so, unless of course you’re left-handed. In that case, just reverse everything I’m saying.

Marcus using feeler gauges

Marcus using feeler gauges

We want to see a little upbow, so halfway between the capo and the 12th fret (that’s on the 6th), there should be a slight gap between the bottom of the string and the top of the fret. This is where your left hand comes in, and possibly that torch light! Use a set of feeler gauges (in Flemish: “voelermaatjes”) to measure the actual distance. You can use the links to buy them, but you should also be able to find them in your local hardware or car parts store.


If you’re not going to buy the feeler gauges (but you should!), you need an alternative. And I’ve come up with one: copying paper!
Excuse me? Yes, copying paper of 80 g/m2  (21 lb) has a thickness of an almost perfect .10 mm. If you cut small sheets and stack them, you may measure .20 or .30 mm as well. It’s clumsy, though. Feeler gauges are a lot easier, and you may also use them for next month’s issue, when we’re going to measure string height.


Regardless of your measuring tools, there is a problem: the optimal distance varies with scale length. And on top of that, individual instruments sometimes require a slightly different distance. There are, in other words, no exact standards. I’ll give you a rough guideline, though: as a starting point, with electric and steelstring guitars, aim for a clearance of .10 to .20 mm (.004 to .008 inches). For basses, .15 to .30 mm (.006 to .012 inches) might work out well.

So now you’ve measured the gap. If the actual distance is not within the intervals I described, don’t panic. You can probably adjust the truss rod enough to get it there. But if the distance DOES seem correct, don’t think you’re done. You still need to make sure the rod is adjustable: seasonal changes may occur and require some tweaking.

At this point you simply HAVE to call the sales person. Request that he or she remove the truss rod cover and demonstrate that the truss rod functions properly! This is VERY IMPORTANT, so don’t take anyone’s word for it. It’s YOUR money; you’re entitled to know what state the guitar is in.
(Here’s another piece of advice, and it’s a valuable one: choose a quiet moment when going to the store. Salesmen will be much more likely to answer all of your questions, and they will probably do so without getting ill-tempered.)


Well my friends, you are well on your way. You already know a lot. Let the information settle for a bit, and don’t forget to practice your sighting and measuring skills. More crucial stuff will follow soon:


  • We’ll dig deeper into the matter of loose or high frets, and you will learn how to detect them. I’ll also tell you about crooked frets, and why to avoid guitars that have them.
  • VERY important: is the bridge mounted in the right position? Is there enough room for adjustment, as far as height and intonation are concerned? Also a word about behind-the-bridge string angle.
  • We’ll discuss nut height and the way it’s influenced by neck upbow/backbow. Nut slot depth and width must also be taken into account. Here, again: string angle.


Pickup height is another factor of the utmost importance, but since it’s usually well adjustable we won’t be discussing it quite yet. We’ll keep that for another time.

Bye now,


Marcus signature



Call to Action


  • Share your experiences. Sighting the necks of your personal instruments, what did you see? Do you think you’re getting better already?

  • Tell me and your fellow readers about the tools you acquired. Feel free to add pictures of them.

  • How did store owners or private vendors react to your questions? Were they friendly, or quite the opposite? We’d all like to know.

  • If you dig this blog, please help out. Share the articles on your Facebook pages. Spread the word.


If reading this post and practicing the necessary skills has prevented you from doing your Christmas shopping, I’m sorry 🙂
In that case, perhaps you might want to try and shop from within my free blog? Buying from the advertising partners (using any of the provided links) contributes to its survival.
But as always: please feel free to do so or not.



  1. Tim says:

    Heya Marc!

    Great blog. Wish you included even more tips! It’s a great first reference though!

    Keep on the awesome blog posts!


    • Marcus says:

      Each month will bring new tips, Tim. And thank you for reading my posts. Don’t forget to share them to keep the blog alive.

      In the meantime: keep ’em vibrating!


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