Cork as bridge shim

Discussion in 'Hardware, Setup & Repair [BG]' started by Artie Langston, Mar 21, 2016.

  1. I recently finished a fretless P-Bass project, which came out flawlessly with the exception of the Omega (Badass clone) bridge being a little low to adjust properly. This is probably due to the thicker ebony fingerboard. I tried various neck shims, some of which worked OK, but then I reconsidered raising the bridge instead.

    I considered various veneers, and then I recalled a luthier telling me some guy came in the violin shop with what appeared to be cork gasket material on the well fitting bridge feet of an upright.

    He thinks the guy is nuts, so he removes the material, and low and behold, he can tell a difference in the sound, and not really for the better. Plus, now there's a "wolf" on one note.

    So, he mutters some obscenities and heads out to the auto store for some replacement cork.

    I considered this experience, and tried the same thing (sort of) with the P-Bass bridge. I made a template, and cut an exact piece of cork of very thin thickness, and placed it under the bridge, and attached the ground wire.

    It brought the bridge up to a perfect height, and it really sounds great. Better than with the many neck shims I experimented with in my estimation. Cork is, of course, tree bark, essentially wood, and with all 5 screws torqued down, it's highly compressed.

    Just wanted to throw this out there if anyone has a similar issue, or just wants to tinker. Bear in mind this is on a fretless instrument with very low action and Thomastic flatwounds. Your sound ideal may vary.
    Last edited: Mar 21, 2016
    GKon likes this.
  2. 10151980_1094623510558508_5914969301992291313_n.jpg 10151980_1094623510558508_5914969301992291313_n.jpg
    Scatabrain likes this.
  3. lz4005


    Oct 22, 2013
    If you like how it sounds, that's great.
    Cork is used in industrial sound and vibration dampening applications, though, so it might not be most people's first choice for a bridge shim.
    mbelue and JustForSport like this.
  4. Killer Canary

    Killer Canary Guest

    Aug 27, 2015
    She looks good, anyway.:thumbsup:
  5. GKon

    GKon Supporting Member, Boom-Chicka-Boom

    Feb 17, 2013
    Albuquerque, NM
    Along similar lines as the ub cork shim you mention, most harley benton/Palatino eub players I've spoken with or read about online, including myself, have installed inner tube rubber under the feet of our bridges.
  6. 96tbird

    96tbird PLEASE STAND BY

    Kind of submarines the high mass bridge arguement doesn't it?
    quickfix likes this.
  7. A great way to subtly mute the sound.:eyebrow:

    Bridge feet on any archtop should be cut clean and precise. No spongy intermediary substances should be placed between vibrating strings and an instruments top. No spongy stuff anywhere unless the purpose is to mute.
  8. 202dy

    202dy Supporting Member

    Sep 26, 2006
    Bark isn't the same as wood. Bark is the protective layer of the tree. It is somewhat like your skin. It is essential but it is not a structural element like your bones. If you build a body out of skin it will be an amorphous lump.

    Does cork make a good bridge shim? Some will say that if you like the sound then it does. Recently Bruce commented on the importance of connection of the bridge to the body as being more important than the mass of the bridge itself. So maybe it doesn't matter what material is used so much as that the mounting screws are torqued properly?

    The few times I've made a shim for a bridge it was for a neck-through instrument. I've used hard maple in each instance because it either matched the body wood or was a close match/compromise to the laminates used in the neck. The results were satisfactory. Any geometry problems with bolt on construction have been solved at the neck joint rather than at the bridge.

    Like everything related to tone, anything you do will affect it. The only question is whether or not it can be measured.
  9. mbelue


    Dec 11, 2010
    This sounds like the feet of his bridge weren't sanded to the same contour as the instrument's top. So the cork gasket was compensating for the poor mating surface. At least that's my theory.

    Exactly. Still at the end of the day...
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