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curvature of bridge top

Discussion in 'Setup & Repair [DB]' started by greitzer, Sep 10, 2005.


  1. This is going to be tough to describe in writing, but I'll do my best. My questions concern the proper slope or curvature of the bridge top, to give the right amount of bowing space for each string.

    It's hard for me to bow the D string cleanly, because its "height" in the bowing area is very close to the height of the G and A strings on either side of it. Particularly when I'm up in thumb position on the D string, it's nearly impossible to get a clean bow stroke without also hitting the G or A strings.

    This doesn't occur with any of the other strings.

    I did some measuring to try to quantify this. Again, this may defy written description but I'll try.

    With my bass standing up in a stand, I laid a ruler flat on the bridge, up against the undersides of the strings. I drew a straight line from the underside of the A the string to the underside of the G string. Then I found that the underside of the D string is about 3 mm above that A-G line.

    Then I drew a similar straight line from the underside of the E string to the underside of D string, and found that the A string is about 5 mm above that line.

    So, in other words, the A is more "separated" in height from its neighbor strings, while the D has less separation in height from its neighbor strings (again I'm talking "height" at the bridge and in the bowing area, not on the fingerboard).

    It may not seem like much of a difference in mm, but it really seems to make the D much harder for me to get a clean bow-stroke.

    Would it be worthwhile to get a new bridge, or get my bridge re-cut somehow? Or do people think this wouldn't make much of a difference? I'd appreciate any thoughts on this.
     
  2. jallenbass

    jallenbass Supporting Member Commercial User

    May 17, 2005
    Bend, Oregon
    Definitely take it to a luthier and get it fixed. That's a very frustrating problem to have.
     
  3. This is easily fixable if you have enough wood left on the top of the bridge to reshape it. But do not do it yourself, take it to a luthier.
     
  4. Thanks for the input. I will take it to the luthier who set it up, next time I get a chance.
     
  5. KSB - Ken Smith

    KSB - Ken Smith Banned Commercial User

    Mar 1, 2002
    Perkasie, PA USA
    Owner: Ken Smith Basses, Ltd.
    If he is the one that gave it to you that way, make sure he knows what he is doing. I just measured my 5-string Bass here at the house which is now my main 'practice' Bass and it's tighter than my 4s by at least 1mm. It measures (about) 4.5mm on the D and 5mm on the A and E. I would recommend 5-6mm but this will depend also on the Arch of the Fingerboard. Shoot for 4mm height under the G at the end of the FB and 10mm at the E. This is only possible if your FB can be rounded enough. keep it between 4 and 10mm. Not higher at the G and not lower at the E. This is a 2mm Difference of String to fingerboard height per string. 1.5mm may work but 1mm may be hard to bow. The Strings need room to 'breathe'.

    Make sure after he re-shapes the top of your Bridge that the Adjusters (if you have them) are no more than 1/4 of threaded screw showing. When my Bridges show more than that, I make a shim and glue it to the non-threaded end of the adjusters that the Bridge anchors on. This helps to save the Bridge and protect your Bass from the Bridge folding into the top if they sitck out too far.
     
  6. Good advice, thanks Ken. Perhaps I'll take it to somebody else, since he is indeed the one who gave it to me that way. There's at least one other luthier I know of in my area that has a pretty good reputation. Maybe I'll take it to him. Thanks again for the tips.
     
  7. arnoldschnitzer

    arnoldschnitzer AES Fine Instruments

    Feb 16, 2002
    Brewster, NY, USA
    Ken mentioned the arch of the fingerboard. This is really the key to a good playable set-up. If the arch is inadequate or uneven the string heights will have to be also. A good example of this is the older Kay basses, which featured a fingerboard that was very flat in the area of the D string path. In order to bow one of these, you have to set the D string way higher than any of the other strings. The result is tonal unevenness and hand pain. All good luthiers understand that the thicker the string, the more room it needs to vibrate. Ideally, there is a little more room under each string, going from G to E. But without a good fingerboard (and fingerboard dressing) little can be done to make a bass play and sound right. So I suggest you look at the fingerboard first.
     
  8. Thanks Arnold, more good advice. I will mention this to the luthier when I see him on Friday. Can you tell me, what exactly is fingerboard "dressing?" Thanks.
     
  9. arnoldschnitzer

    arnoldschnitzer AES Fine Instruments

    Feb 16, 2002
    Brewster, NY, USA
    Planing, scraping and smoothing the fingerboard to proper shape, arch and camber.
     
  10. KSB - Ken Smith

    KSB - Ken Smith Banned Commercial User

    Mar 1, 2002
    Perkasie, PA USA
    Owner: Ken Smith Basses, Ltd.
    No No Arnold.. It's French, Russian, Blue Cheese, Lemon Oil or Linseed.... You need to get out more Arnie....lol
     
  11. arnoldschnitzer

    arnoldschnitzer AES Fine Instruments

    Feb 16, 2002
    Brewster, NY, USA
    On an Italian bass, you polish the board with olive oil. On a Chinese bass, peanut oil. On a French bass...
     
  12. KSB - Ken Smith

    KSB - Ken Smith Banned Commercial User

    Mar 1, 2002
    Perkasie, PA USA
    Owner: Ken Smith Basses, Ltd.
    Will that work for Old English Italian Models or just rub a Tea Bag on the FB?