Shims in the neck pocket; What's the deal?

Discussion in 'Hardware, Setup & Repair [BG]' started by madjazzbass, Apr 22, 2018.


  1. madjazzbass

    madjazzbass

    Jan 5, 2014
    Earth
    I have a Bass that I can't get the action nearly low enough and I can't adjust a truss rod anymore or I'll end up breaking it, and I've lowered the bridge as low as it can go. I've heard about people using shims in the neck pocket, but I don't know what to use for a shim to put in the neck pocket. What do people use to do this? They're obviously put their to tilt the neck backwards in order to get the action lower, but I need some help/ guidance on what type of material(s) I should use as a shim. Thanks.
     
  2. Hurricane Jimmie

    Hurricane Jimmie Supporting Member

    Business cards will work.
    And you might want to have a tech take a look at it and start over with a complete setup.
    Good luck to you.
     
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  3. briandavismurph

    briandavismurph

    Jul 1, 2013
    Chicago
    The key is a material that does not compress, very thin hardwood veneer is good, mylar plastic sheet is good, you may not need much thickness at all [.05 inch]
     
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  4. madjazzbass

    madjazzbass

    Jan 5, 2014
    Earth
    Yeah Thanks; That was the other thing; How thick should it be or not be, Thanks.
     
  5. briandavismurph

    briandavismurph

    Jul 1, 2013
    Chicago
    If you run a straight edge [36 inch] along the fret board then to the bridge it should meet the bridge right at the saddle top. if the saddles are all the way down and the bottom of the straightedge hits the saddle in the middle add shim thickness to change the neck angle until that angle is acheived. I like to have my saddles up a bit to allow downward adjustment
     
  6. gebass6

    gebass6 We're not all trying to play the same music. Supporting Member

    I've used .062 brass strips.
     
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  7. GIBrat51

    GIBrat51 Innocent as the day is long Supporting Member

    People have used just about anything you can imagine for a shim. As long as its; flat; fairly thin; and not too squishy, it will probably work. Lots and lots of business cards have become shims; lots of playing cards have, too. Some instrument companies (like Fender) like to use a piece of sandpaper to shim a neck at the factory. But, paper will compress over time - just a little. But, it takes quite a while - years and years, sometimes. A lot of people prefer wood shims. You can buy full sized, tapered wooden ones; or you can just use a small piece of thin wood veneer (which comes in various thicknesses). Wood is much less compressible than paper, if worrying about that might keep you up at night. Being a compulsive, engineering type myself, I like to use pieces of aluminum beer/soda cans, or plastic bottles, for shims. 'Cause they won't compress at all, under any force a bass neck & 4 screws will generate. But, that's just me. A piece of business/playing card will work perfectly well. As for "how thick"? If you use a small shim at the very heel of the neck, I'm pretty sure the ratio of thickness to the height increase at the bridge is about 1:6. That is, a 1mm thick shim will get you about 6mm of height at the bridge. It doesn't take much...:thumbsup:
     
  8. madjazzbass

    madjazzbass

    Jan 5, 2014
    Earth
    Thanks a lot
     
    CountryCliff likes this.
  9. Spectre1966

    Spectre1966 Striving For Mediocrity Supporting Member

    Jul 4, 2014
    Wallingford, CT
  10. Slater

    Slater Leave that thing alone.

    Apr 17, 2000
    The Great Lakes State
    Truss rod adjustments are to set relief, a slight curvature of the neck, to help eliminate string buzz. A combination of setting relief, a properly cut nut, and bridge saddle height, should be used to get your desired “action”. If you’re adjusting the truss rod just to change the string height, you’re asking for problems in other areas.
     
  11. mech

    mech In Memoriam

    Jun 20, 2008
    Meridian, MS, USA
    @madjazzbass ....you're going to need less thickness than it looks like. Try one piece of business card between 3/8 and 1/2" wide first. Cut it to fit the body side of the pocket. Not enough? Add another. I've rarely seen the need for more than two and one piece has taken care of 95% of the instruments I've worked on. It's not worth buying the Stu-Mac shim. You won't be able to tell the difference, IMO.
     
  12. madjazzbass

    madjazzbass

    Jan 5, 2014
    Earth
    Thank you Sir, I will definitely try the business cards... By the way; What about an old credit card? Wouldn't that work as well? I mean, they don't compress right?
     
  13. Slater

    Slater Leave that thing alone.

    Apr 17, 2000
    The Great Lakes State
    Old credit cards have been used successfully for shims many times, by many people.
     
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  14. Bassbeater

    Bassbeater Guest

    Sep 9, 2001
    Sadly, or gladly, nearly any piece of properly proportioned durable trash object will do the job. Even the finest bass may have picks, cards and parts stuffed in its nether-regions to good effect.
     
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  15. Pilgrim

    Pilgrim Supporting Member

    There are many, many threads on neck shimming, some of them with extensive directions on, and discussion of, ways to use shims.

    I suggest searching and reading, as there is a lot of good info to be had. (And it doesn't all need to be repeated here.)
     
  16. mech

    mech In Memoriam

    Jun 20, 2008
    Meridian, MS, USA
    They work well if that is the thickness needed...... around .030" thick...about twice the thickness of a slick business card.
     
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  17. JLS

    JLS

    Sep 12, 2008
    eureka, ca
    I setup & repair guitars & basses
    But what about the dreaded, "air space", under the heel, that can cause ski jump?
     
  18. Bassbeater

    Bassbeater Guest

    Sep 9, 2001
    For some reason we all want it to matter. We are convinced that it should matter, but it truly mostly doesn't. You can get away with murder when shimming. It seems like side to side neck pocket snugness is way more important for whatever (physics) reasons.
     
  19. mech

    mech In Memoriam

    Jun 20, 2008
    Meridian, MS, USA
    I've seen more necks with ski jumps that have never had a shim or neck tilt screw used than from using either. If you inspect many with ski jumps you will notice the jump is much more than could ever be caused by a .010 to .030" shim and it is almost never between the screws. IMO, ski jump is caused by the strength of the individual piece of wood, grain/how it's sawn (part of strength) and most important, the profile blend from the thick heel to the slimmer neck. Most ski jumps form in the transition area , IME. Too quick a transition from thick to thin is not a good thing for preventing ski jump no matter the other factors. Also the neck screws don't have to be "that" tight. Good and snug with no strings or slacked off is all that's required and tighten the screws at the neck end of the pocket first to set the angle for an ounce of prevention. After working on a couple of 5 strings by a well respected "F" company in the past year I'll make a fearless forecast that within 10 years more of them will have ski jumps than not to a greater or lesser degree......most likely greater.
     
  20. Primary

    Primary TB Assistant

    Here are some related products that TB members are talking about. Clicking on a product will take you to TB’s partner, Primary, where you can find links to TB discussions about these products.

     
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