How and when to shim?

Discussion in 'Hardware, Setup & Repair [BG]' started by odie, May 13, 2003.

  1. odie

    odie Supporting Member

    Ive heard of people doing this to get there action lower when the bridge bottoms out. When else do you do it?? Is there a way to shim to get the action even across the neck??

    You see I hate the fact that some basses have a high action higher in the neck(12th or so on up) than in the first postion. I wish I could have it more flat and even.

    The neck is fairly straight but I would like the action lower in the upper register.
  2. pkr2


    Apr 28, 2000
    coastal N.C.
    Generally speaking, shimming is only done to get the bridge height adjustment screws into range. It can have some secondary effects such as a softer or harder feel to the action due to changing the break angle across the bridge.

    Shimming to get the action even across the neck is unnecessary. The heigth adjustments on the bridge rollers take care of that. If a bass is properly set up the strings aren't even across the neck. There should be a bit more string to fret clearance under the largest diameter strings.

    Any and all basses MUST have a lower action in the first few frets and higher action as you go further up the neck. If the action were the same all over the neck the nut would have to be WAY too high and the action further up the neck would have to be way too low. Also the neck would have to be dead straight. In other words, yes, the bass could be adjusted that way but it would be totally unplayable.

    The ideal geometry is a gradual increase in string clearance from fret 1 to fret 5 and equal clearance from fret 6 to the last fret.

    I hope all of this makes some sense to you.:)

  3. That's my experience, too...I agree 100%.
  4. jani_bjorklund


    May 22, 2002
    Fender type basses and most other as well don't have a neck angle. In other words, the neck is parallel to the body. If you for some reason need to rise the strings in relation to the pickup(s) then there might be a need for shimming. If you're on the other hand satified with the string height there is no need for shimming. Apart from adjusting the neck angle I have in some cases seen shims used to make the neck fit better in a loose neck pocket.
  5. Lackey


    May 10, 2002
    Los Angeles
    Well,, apparently having even action up and down the board is possible,, Anthony Jackson himself promotes it!
  6. pkr2


    Apr 28, 2000
    coastal N.C.
    Apparently you have heard something that I haven't! Jackson does advocate a straight neck but that is by no stretch of the imagination the same thing as equal action height at every fret.

    A perfectly straight neck along with almost perfect fret dressing is playable, but only with an EXTREMELY light touch. A straight neck that is playable has no two frets with the same string height. The exact opposite of even action.

    Frankly, I don't care who advocates a straight neck setup, it's not the correct way to set up an instrument. I don't know of one single builder or manufacturer that advocates a straight neck.

  7. Eric Moesle

    Eric Moesle Supporting Member

    Sep 21, 2001
    Columbus OH
    I've never shimmed a neck, personally, but one thing I do every time I get a new bass is level the frets (unless its a really high-end bass like an MTD).

    For my taste, new frets are typically way too high, and I can't get the "buzzlessness" I want with the action as low as I want, so I file down the frets a bit, and recrown them (not rocket science, but must be slow and patient, with an eye on detail). I make it a point to take a tad extra off the 14th fret and above, since that's where the action tends to buzz if set extremely low.
  8. odie

    odie Supporting Member

    Thats a good idea!! The best playing basses that I own are always the oldest, vetrans that have had a lot of playing. Maybe that is the key!!