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I Totally Suck At Using A Feeler Gauge To Measure Relief

Discussion in 'Luthier's Guitar & Bass Technical Discussion' started by freedomspec, Feb 11, 2019.

  1. freedomspec

    freedomspec Member

    Messages:
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    Location:
    Melbourne, Australia
    Is it just me?

    I can't figure out how people get good results measuring action with a feeler gauge.

    Every time I use a feeler gauge, I end up with what looks (and feels) like about double what I was aiming for. For example, if I'm trying to get relief of 0.01" (0.25mm) using a feeler gauge, I end up with about 0.40mm instead, according to my StewMac String Action Gauge.

    At first, I thought I was using the Action Gauge incorrectly. I thought that maybe I was reading the gauge behind the string at an angle, kind of from beneath the string and up at the gauge, but I'm sure I'm not doing that because I made a point of looking at it from the correct angle. Further, if I try to set the relief at 0.01" with a feeler gauge, if I eyeball the result, the gap just looks way too big compared to the 0.01" notch on my StewMac Action Guage.

    I've tried sweeping the gauge side-to-side between the string and the 8th fret, feeling for a bump as I pass over the fret; I've tried inserting the gauge inward between the string and the fret - I keep getting the same wrong result.

    What am I doing wrong? Should I persist and try again with a new technique, or should I just stick with my Action Guage?
     
  2. Timtam

    Timtam Member

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    I'd be doubtful that you can accurately measure 0.25mm between fret and string on any ruler, including the Stewmac action gauge. It's not really designed for that, even though it may have gradations that go that low.

    Having said that, feeler gauges for relief are a tad fiddly too. The difference between slipping the gauge under the string versus displacing the string upwards is slight. If you're out by as much as you think (almost 100%), the 0.25mm feeler gauge would be slipping under very easily. If it doesn't, I'd trust the gauge not the ruler.

    With time you get more confident that you're on the right track, and get a feel for the right gap size even when you just press down on the string (ie without the gauge).

    Other things worth doing in the meantime ...
    - try doing relief with a straight edge instead of the string. That way you avoid your feeler gauge pushing the string up. Just be aware that your 'straight' edge may not be perfectly straight.
    - use a short piece of 0.10" (0.25mm) high E string in place of the feeler gauge to slip between the fret and the string; also measure that string piece with digital calipers and against the supposed 0.25mm gradation on the Stewmac ruler
    - check your 0.25mm feeler gauge with digital calipers
     
    Last edited: Feb 11, 2019
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  3. Ayrton

    Ayrton Member

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    Considering how much wood moves trying to get such a precise measurement is a fool's errand. Use a string action gauge for height and your eyes for relief.
     
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  4. Moby Dick

    Moby Dick Member

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    You’re not alone or at fault for struggling measuring neck relief with feeler gauges.
    I have been using feeler gauges in my career for 25 years and I don’t like and don’t use steel feeler gauges or steel shim stock.
    I use plastic shim stock or plain old printer/copy paper.

    What I do is capo the first fret and hold the guitar in my lap as I would be playing it.
    I fret the high e at the 15th fret and using my left hand, I take plastic .0075in white precision brand shim stock cut into a .5in x 3in strip and slide it between the lowest point of the neck(usually 6 fret) and the string.

    Because the plastic shim is so light if the clearance between the string and the fret is LESS than the shim, the shim will stay trapped between the string and the fret when I let go of it.
    Steel shim will not stay because of its mass and the finish of steel shims is smooth.

    Once the shim starts to grab between the fret and the string I know I’m where I want to be. You can make minor tweaks from there but once I set it for .0075in I’m usually whee I want to be.

    You can also use plain copy paper in the same manner.
    You would just need to make layers by folding it until you get the thickness you’re looking for.
    Printer paper is around .0035in thick.
     
    Last edited: Feb 11, 2019
    sjwieczorkow likes this.
  5. sjwieczorkow

    sjwieczorkow Supporting Member

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    Using feeler gauges to measure relief is about as impossible as making a perfect guitar nut on the first try. Plus, the oil that is between them to keep the gauges from sticking gets all over. For cars, bring it on!
     
    Jeffj likes this.
  6. LReese

    LReese Member

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    A few things that worked for me. Still, I think its kind of an art.

    1. Magnification
    2. Magnification
    3. Magnification.

    I don't care how good someone thinks their eyes are, you'll need to see if the string moves slightly or there is gap. Once you get in the ballpark, that's when judgement comes into play, hence calling it an art.
     
  7. Killed_by_Death

    Killed_by_Death Member

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    I'm sorry that you wasted money on a string-action tool that you could have done with a machinist's steel rule.
    Get some of those 3x reading glasses at the Dollar Tree, much more bang for buck!
     
    blondestrat likes this.
  8. Tone_Terrific

    Tone_Terrific Supporting Member

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    The measurement does not matter.
    Relief needs to be set for best performance wrt action and player's reference.
    After you get it set up properly then you can measure it but it is entirely a moot point.
    Things change and you tweak it back to preferred performance again.
     
    Qstick333, 9fingers and GA20T like this.
  9. Khromo

    Khromo Supporting Member

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    I measure relief using feeler gauges and a straight edge, not a string. The straight edge stays wherever I hold it, and it does not deflect like a taut string. Easy, reliable, repeatable, cheap!

    Nothing wrong with doing it by eye, you can get great results that way.

    I just like to measure on a customer's guitar, when I want to be able to duplicate it just the way the customer prefers. I like to record the relief with string tension and with no string tension for regular customers.

    "Can you get my Strat feeling more like my Les Paul?"

    "Well, maybe to some degree. I would start by getting precise measurements from the one you like and trying to duplicate them onto the other guitar (with a different scale length), and go from there. Sound good?!?!"
     
  10. Ayrton

    Ayrton Member

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    That is a different scenario. You are having to try and replicate versus just setting up your own guitars.
     
  11. 70 Mach 1

    70 Mach 1 Supporting Member

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    I been gapping points since 1977.
    So i got use to how to use a fg.
    Its an applied art.
    Khromo made some good points.
    Follow that.
     
    willyboy likes this.
  12. 9fingers

    9fingers Supporting Member

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    This, there is no real "spec" for relief as it is so dependent on the condition of the fretboard and how perfectly level the frets are. It just has to be gotten so the guitar plays as well as it can. If it is fretting out in the middle of the neck or at the upper frets that does say that the relief is not enough or too much, but beyond that a good eyeball and then retuning and playing (through an amp if it is electric) tells the true story, repeating as necessary. A magnifier helps a lot for the eyeballing.
     
  13. paulg

    paulg Supporting Member

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    Press the string down at the first and fifteeth fret. Eyeball the distance (relief) at the eighth fret. Is the setup to your satisfaction? If so, commit this measurement to memory. In the future, if the action seems too high or low. Repeat the process. Chances are you need a slight tweek of the truss rod.
     
  14. pats

    pats Supporting Member

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    Check out this video at about 3:00 mark

     
  15. halcyon

    halcyon Supporting Member

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    I don’t bother measuring this with super precision myself. Depress at 15th fret and there should be just a small amount of clearance at around the 8th fret — like, a piece of glossy paper or a biz card. You’ll learn to know it when you see it and you won’t need feeler gauges.
     
    Last edited: Feb 12, 2019
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  16. 9fingers

    9fingers Supporting Member

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    For those that say "a business card of relief", I measured various business cards with digital calipers out or curiosity. They were anywhere from .006" to .015".
     
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  17. Khromo

    Khromo Supporting Member

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    With my personal instruments that are really level and familiar, I find it easy enough to do it by ear. It's a useful quick-and-dirty test if you do it often enough. Tapping a taut string and watching the deflection also works, in noisy environments.

    I fret at the first fret and right above the neck/body joint. Then with my third hand or just by reaching over there, I tap the string at about the midway point. If I get the slightest audible click, and I can't really see the string move, then I am good with that guitar. That's almost straight, but the click tells me I have enough relief to play as cleanly and as low as I will want on that particular guitar.

    One scenario where actually getting a fairly accurate measurement with a straight edge and feelers might be when you encounter a neck that doesn't seem to be acting right, either not reacting to truss rod adjustments or just not playing the way they are supposed to.

    I also get twitchy when I get dual rods. I spend extra time making sure I am not building a twist in there. Measuring both sides makes me feel confident before I button it up.
     
    Harryq likes this.
  18. walterw

    walterw Gold Supporting Member

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    was jumping in to post this!

    a piece of guitar string makes a great feeler gauge, far easier to tell when it slips through and when it catches in the gap. if you want to get fancy you can make a tool out of a little piece of dowel rod with a tiny hole drilled in one end and labeled as to size, stuff your piece of string in there. i like to put a right-angle bend in that string so as to keep the thing from stabbing anybody.

    that said i've left them behind long ago, it's an eyeball/finger tap test like @Khromo for me. i'm shooting for dang close, like smaller than .008", basically as close as i can get without actually touching.
     
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  19. RicOkc

    RicOkc Member

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    Location:
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    Everyone has their own way of setting-up their instruments.

    For a few years I had taken my guitars to so called "tech's" and realized that I had wasted my money using these guys, and that I was never satisfied with the work they'd done.

    When I started doing my own set-ups there wasn't an internet or YouTube to refer to. I learned a lot from articles in Guitar Player magazine posted by some of the major luthiers in the country. And luckily I had a Martin authorized repairman in my town (the only one in a three state area) that could answer my questions, and another luthier who had been trained by him.

    Doing my own set-ups I use four tools...A tuner, 2 wrenches for the truss rod and bridge saddles, and a 6" machinist rule.

    I use the "E" string fretted at the first fret and the last, sighting the distance about mid way for the gap between the fret and the bottom of the string. All my measurements are taken at the last fret using the machinist rule (which I also use to set the radius of the bridge saddles). Strobing the bridge I use the open string & the 12th fret.

    After doing this for many years I took one of my guitars to a friend who's a professional luthier and asked him for his opinion on the work I had done and for any comments/recommendations. His answer was "Looks good to me and he saw no issues".

    About a year ago I was curious and had some time to waste, so I looked up the spec's on Fender & Gibson's websites on their recommendations on set-ups.

    I broke out the capo, feeler gauges, ruler, wrenches, hammers (just kidding) and whatever else they recommended to use for their recommended set-ups.

    Using their recommended procedures I found my neck relief settings to actually be lower than they advised, with no fret buzz at all.

    Some of you might say that I must have above average sight to do all of this. WRONG....I wear glasses & have progressive bi-focals. Yup....I'm a half blind old geezer (65).

    Of course there are some factors like high/low frets. warped necks, ect. I've luckily not had any of those issues with any of my instruments (And I've owned many over the years). But I thoroughly check out all my purchases and only buy locally.

    Now...I know the bashing will probably start after I post this. OK.....Like opinions we all have two feet and most of them stink....LOL Just kidding.

    Everyone has their own way of doing this things and if it works for you, that's great. But....You don't have to go and buy all the latest gadgets from StewMac or whoever to do your set-ups.

    Sometimes like they say "Less is more".

    Save yourself time and money and learn to do your own work, it's really not that difficult or expensive, just take your time. And if you have problems with something you can't resolve on your own look for a luthier, not the guy who says he's a tech from GC. Or ask the local players who they take their instruments to for repair.

    Good luck!!!
     
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  20. blondestrat

    blondestrat Member

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    Lots of good responses but I'll try to add something new:
    You can try holding the feeler gauge so it kinda follows the radius of the fret and then tilt the feeler gauge so it is in line with the string. If you tilt it it will throw off a reading. This will give off a super accurate result along with a steady hand. You can also pluck the string and wait for it to decay and only vibrate a tiny bit, then stick the gauge under. You're just trying to get in the ballpark of what a pretty straight neck is but not too striaght, to plenty of releif but not too much. Then fine tune by eye and feel afterwards. Again, eventually you might want to be able to just eyeball it and feel it once you get the hang of it.
    I often see people talking about measuring saddle height action, sure eyeballing it and doing it by feel is great, I can do it, but there is nothing wrong with getting a reference point by measuring until you get the hang of it. It is just a hobby and it's your guitar.
    Actually measuring can give you a good understanding, like is the action following the radius well?

    One you get the hang of basic neck relief measurements, you should start doing them by eye and feel instead.
    Don't overspend on tools. Have fun.
     

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