Volume knob that's higher/taller than others?

Discussion in 'Luthier's Corner' started by BenTobith, Feb 27, 2020.

  1. BenTobith

    BenTobith New Member

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    On my SG Standard, one of the Volume knobs is a bit higher than the others. I tried using some force to press it down, but no-go.

    Anyone run into this? Maybe the actual post/nut/washer is not as tight as the others or something?

    Not a big deal, just bugs me when I look at it. :D
     
    Dagger likes this.
  2. donepearce

    donepearce Well-Known Member

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    Piccy from the side?
     
  3. BenTobith

    BenTobith New Member

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    Here's a pic.
     

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  4. donepearce

    donepearce Well-Known Member

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    If you can prise off those two knobs, you will probably find that either one of the controls has a longer shaft, or it has been mounted a bit higher up on the nut. But just in case, check the depths of the holes in the two knobs. One may have a bit of debris in the bottom.
     
  5. BenTobith

    BenTobith New Member

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    Okay, I'll take the knobs off and see what I can see. Thanks!
     
  6. DrBGood

    DrBGood Well-Known Member

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    If and when you press the knob down on the shaft, be sure to the same upwards amount of pressure at the bottom of the pot, because you can blow out its intestines in the control cavity. Not a pretty picture.

    The split shaft can also be pried to make it a tad slimmer/looser. But do it very gently, those two legs can easily break.
     
    BenTobith likes this.
  7. AngelDeVille

    AngelDeVille Well-Known Member

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  8. Col Mustard

    Col Mustard Well-Known Member

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    Welcome to ETSG...

    Don't use any excessive force, if you break the pot inside, it will likely
    need to be replaced. I learned this the hard way, of course.

    You haven't told us how old your SG is. If it's old, and you bought it second hand,
    it's possible that someone replaced pots, or replaced knobs.... improperly...

    These things don't always match perfectly, or fit. If your guitar is stock, the pot shafts
    are likely to be Gibson branded parts... and these have what's called "Split shaft, fine Knurling"
    where the knob fits on.

    https://www.stewmac.com/Pickups_and_Electronics/Components_and_Parts/Potentiometers/

    It's up to the guitar owner to know about fine knurling vs Coarse Knurling when it comes to
    buying potentiometers and knobs for them.

    So before any of us can answer your questions intelligently, we need to see a photo of the
    inside of the control cavity... like this:
    wiring 2013@100.jpg
    Here we have stock Gibson wiring, with no PCB and a set of stock Gibson 500k Ohm potentiometers.
    This is from a 2012 SG special. It's obvious from this photo that no one has disturbed the factory
    wiring. And so all the pot shafts fit all of the knobs, the way they are supposed to.

    We might also need to see photos of the pot shafts with the knobs removed. Like this:
    Luna Top @100.jpg
    This photo shows new CTS pots, newly installed, with Coarse Knurling. Right after I took this
    picture, I tried to shove a knob onto one of these, and broke it by pushing too hard. It was the
    wrong knurling, it didn't match, and I could NEVER force it onto the shaft. I didn't know all
    this, and breaking it was how I learned.

    Don't do that. Learn first, and then shove. Note that I didn't say shove it. *grins
    ...that part is understood. Welcome to ETSG!
     
    fredlw likes this.
  9. Dagger

    Dagger Member

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    Like the Col said we've all made some mistakes so you don't have to. I myself pushed some knobs on some Emerson control pots and the shafts became all wiggly, of course I partially blame the poor design of the Emerson control pot because the shaft goes right through the centre and out the back of the pot. I won't be buying Emerson pots again as they had to much play in the shafts to begin with.
     
  10. Greg Coats

    Greg Coats New Member

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    Using Force on a guitar leads to serious heartache imho If your mantra is "If it don't fit force it" then may I suggest a career as a drummer. In all seriousness I agree that the pot was prolly replaced with the wrong shaft length.
     
  11. SunDogAZ

    SunDogAZ New Member

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    You may need to add another washer or two to the pot, but on the control cavity side, to reduce the height of the pot shaft coming thru the body.

    So, in cases where one (or more) pot shaft comes thru the top of the body and sits higher than the other pots, I do this:

    - remove the knob
    - remove the nut and washer
    - remove the control cavity cover
    - from the control cavity side, carefully pull out the pot in question from its mounting hole, just enuf to add a washer or two to the pot shaft
    - place the pot back thru the mounting hole
    - on the top of the body, put back on that washer and nut (don't over-tighten)
    - put back on knob (being mindful of the knob number alignment)
    - check for height
    - you may need to add another washer

    If you don't have spare "star" or those thin flat washers that usually come with pots, you can use a flat washer from the h/w store, provided it is fairly thin. Just take one of your existing washers with you and get as close a match from the h/w store. Buy a few, they are cheap, you may need more in the future!

    Good luck!
     
    Last edited: Mar 4, 2020
  12. SunDogAZ

    SunDogAZ New Member

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    One thing I have done a few times with a knob that doesn't have matching knurling to the pot I want it to go onto is to use a drill bit that is just the right size to fit in the knob hole just barely, and I will carefully drill out a thin layer of the knurling to make it fit onto the knob. YMMV.
     
  13. Biddlin

    Biddlin Well-Known Member

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    I wonder why we have a forum titled "Luthiers Corner?" sigh............................
     
    kingmlg likes this.
  14. Relic61

    Relic61 Well-Known Member

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    Gently take the tiniest hammer and...

    /[​IMG]
     
    Alex Kendall and Daniel.S like this.
  15. Gibbo SG

    Gibbo SG Active Member

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    Either take it to a tech or let it ride. Pull a DIY and you may be sorry.
     

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