Setting the action – Shimming?

Discussion in 'Basses [BG]' started by Band Dad, Jul 21, 2009.

  1. Band Dad

    Band Dad

    Dec 5, 2006
    San Mateo, CA
    This might be better in the Luthier's Corner, but as an action adjustment question, I thought I'd run into more opinions here.

    Fender P bass with a Modulus BaSSStar neck. Not a perfect fit (necks a touch narrow in the pocket), but a great neck on a great body.

    The neck has no truss rod, but rather has a certain amount of built in relief. I can't flatten this neck, but the action is quite high in the upper register. The saddles are about as low as I think they should go without buzzing on the 21st fret with finger on the 19th.

    Should a certain amount of fret buzz be expected?

    Would shimming the neck be the way to go? And would I be shimming to raise or lower the headstock? What are good shimming materials?

    Also, the wraps on the strings cleared the nut on the stock P neck, but with the Modulus neck, a couple of them want to rest about halfway into the nut. Can the wraps be trimmed so as to prevent this?

    No ready cash to take this to a pro just yet. Thought I'd go it alone for now. I'm comfortable with making any adjustments, but not sure just what I'm facing here.

    Thanks for any input.
  2. A shim does exactly the same thing as lowering the bridge saddles- it lowers the action. There's no magic. You'd put the shim at the base of the neck(under the last frets) to do that.
    Now, if the action is higher than you'd like, but you have fret buzz, you need a fret dressing. Some buzz is normal, but everybody has a different idea as far as what's acceptable or not.
  3. Band Dad

    Band Dad

    Dec 5, 2006
    San Mateo, CA
    I can see where shimming is the same as saddle adjustment, so I'm thinking that the issue may have more to do with neck relief, for which there is no cure in this instance. Perhaps a fret dressing as part of a complete setup would help. The frets are a bit wider (thicker? Beefier?) than the stock neck frets.

    As a side note, because I have the stock Fender neck off the bass for the first time, I notice a couple of things: the lands (that part of the fret crown where the string actually hits) is rather wide. That is, the fret profile is somewhat squarish, as opposed to the Modulus which has fairly rounded frets. Also, the neck varnish rides up the fret to an extant that only the very top of the frets (as I say, they are squarish) is free of varnish, unless having been "chipped" away by the strings. Even some suggestion that the varnish rides over the fret crown in some places, not having been worn away by playing. Seems to have been lightly used. All original. I haven't seen this before.