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Thread: Shim for Bridge Insert.

  1. #1
    Registered User mandrian's Avatar
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    Default Shim for Bridge Insert.

    Hi,

    I want to raise the action slightly by shimming the bone insert in my bridge (African Blackwood).

    What would be the best material to use? I don’t have access to bone, but have seen wood, hard plastic and paper card used.

    Under lockdown here, so needs to be a DIY job and I don’t want adversely impact tone by my material choice, but want to keep the job as simple as possible.

    Is there an obvious best choice?

    Do you need to physically attach the shim to the bottom of the bone insert or simply place it below it in the bridge?

    Thanks for any advice offered from those with the specific knowledge of the topic.

    Regards,

  2. #2
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    Default Re: Shim for Bridge Bone Insert

    Two things I have used for convenience are a maple laminate that I have and plastic packaging material. That hard plastic that you have to open to get to your product. Both can be cut with scissors and are fairly even in thickness. I simply place the shim, not too many now, under the saddle. You will want to make sure you still have enough saddle into the bridge to not tip under string pressure. I have not noticed it changing the tone. Here the winter dries out instruments even if you humidify and the action changes, short of having two saddles, shims are convenient.
    THE WORLD IS A BETTER PLACE JUST FOR YOUR SMILE!

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  4. #3
    Moderator MikeEdgerton's Avatar
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    Default Re: Shim for Bridge Insert.

    Mandrian, I fixed it for you

    Happy New Year.
    "It's comparable to playing a cheese slicer."
    --M. Stillion

    "Bargain instruments are no bargains if you can't play them"
    --J. Garber

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  6. #4
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    Default Re: Shim for Bridge Insert.

    Quote Originally Posted by mandrian View Post
    ... have seen ... paper card used.
    Remember that paper and cardstock are simply reconstituted wood, possibly with higher density than most, and certainly higher consistency.

    Wish I could remember who but, 10 years ago or so, one of the respected luthiers here admitted to using layered Post-It notes to determine the final amount of nut shim needed. That trick has helped me more than once!
    - Ed

    "Then one day we weren't as young as before
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  8. #5
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    Default Re: Shim for Bridge Insert.

    I make shims out of slices of soda or beer cans. Just cut it with tin snips...or old scissors. Also, you can get brass and aluminum shim stock of various thicknesses from some auto parts stores. I just make sure it is the right width and lay it in with no cement or glue.

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  10. #6
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    Default Re: Shim for Bridge Insert.

    Quote Originally Posted by ajh View Post
    ... shims out of ... beer cans. Just cut it with ... old scissors.
    Whoa!!! (Yes, THREE exclamation points.) Major head-rush / recollection from, what, forty+ years ago??

    In "Zen and the Art of Motorcycle Maintenance", two friends are sitting by their evening campfire in the wilderness, probably Montana. While one bemoans the fact that it'll take three weeks to get a handlebar shim sent from the BMW factory, the other, with Swiss army knife, turns his just-emptied beer can into a shim and half-way installed before the first one realizes ... You get it!

    At least, that's my recollection. Probably a lesson in there for instrument maintanance too!
    - Ed

    "Then one day we weren't as young as before
    Our mistakes weren't quite so easy to undo
    But by all those roads, my friend, we've travelled down
    I'm a better man for just the knowin' of you."
    - Ian Tyson

  11. #7

    Default Re: Shim for Bridge Insert.

    About the beer can shim in the book...the question, or was it a statement, in the book remains: What is best.

  12. #8
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    Default Re: Shim for Bridge Insert.

    Mandrian,

    Another idea from a local luthier as a quick fix: cut the shim out of old celluloid guitar picks. He used medium on an old guitar I bought that had been set up way too low, to tide me over until I got a new bone saddle in from Stew Mac. Worked very well, and, honestly, I think any difference in tone I noticed was the bone saddle replacing the previous Tusq material...and, it wasn’t a huge difference...
    Chuck

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  14. #9
    Barn Cat Mandolins Bob Clark's Avatar
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    Default Re: Shim for Bridge Insert.

    I have used thin flat shims of maple and bone. Both worked fine and I didn't hear any difference between the two. I have made a couple of these bridges and the shims make them quite adaptable.

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  16. #10
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    Default Re: Shim for Bridge Insert.

    Quote Originally Posted by Eric Oliver View Post
    About the beer can shim in the book...the question, or was it a statement, in the book remains: What is best.
    Whoa!! A philosophical question, far more than I realized way back when I read "the best-selling philosophy book of all time", according to Wikipedia.

    The answer, IMHO, is "it depends": Do you want to keep your expensive bike (mandolin?) "pure" -for big bucks & much waiting-, or would you rather get home before the coming blizzard -for the no bucks/no waiting functional equivalent, just without the (forevermore hidden) factory approval stamped on the, uhm, headstock? Or maybe get to tomorrow night's jam session?

    (Feel free to ignore: Not trying to overwhelm, but I found Wikipedia most informative:
    https://en.wikipedia.org/wiki/Zen_an...le_Maintenance)
    - Ed

    "Then one day we weren't as young as before
    Our mistakes weren't quite so easy to undo
    But by all those roads, my friend, we've travelled down
    I'm a better man for just the knowin' of you."
    - Ian Tyson

  17. #11

    Default Re: Shim for Bridge Insert.

    Ed, Pirsig’s gone, the bike is in the Smithsonian, and we’re shimming mandolins and trying to define quality. The time is past, I think, for Zen and the Art of Mandolin Repair to redefine formal philosophy, but the dichotomy between the hands-off Bimmer couple and Pirsig (or his Greek avatar) still exists, at least in these forums. Will a shred of beer can mystically pollute a bridge; the term ‘bridge’ itself having extraordinary resonance, acoustical and philosophical? Is quality a function of personal craftsmanship, embodied by superficial varnishes, something not found in soul-less machine production?
    Well, I’m becalmed this year, shut out of both shop and home, so maybe I’ll kick back and think about such deep issues.
    Or not.

  18. #12
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    Default Re: Shim for Bridge Insert.

    Deep issues indeed! But then again ...

    On Netflix' 2020 year-in-review special, Leslie Jones, recently of Saturday Night Live, commented (approximately):
    "I'd like to say that 2020 was a trainwreck of a sh**show, but that would give a bad name to both trainwrecks and sh**!"
    - Ed

    "Then one day we weren't as young as before
    Our mistakes weren't quite so easy to undo
    But by all those roads, my friend, we've travelled down
    I'm a better man for just the knowin' of you."
    - Ian Tyson

  19. #13
    Mando-Accumulator Jim Garber's Avatar
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    Default Re: Shim for Bridge Insert.

    I found a roll of iron-on hardwood veneer at Home Depot and added a layer at a time to the bottom of my wooden bridge. It conforms to the curve nicely. IIRC I might have used two layers under an ebony bridge, trimmed the extra and then used a black Sharpie to match the ebony. It worked quite nicely and didn’t affect the sound.
    Jim

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