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How do I enlarge the bridge's string hole?

Discussion in 'Hardware, Setup & Repair [BG]' started by bassnyc1, Apr 1, 2014.

  1. Hi everyone,

    I'm looking for some advice. I have a BadAss V bridge on my custom Valenti bass. When I use a .125 B string, it's a bit tight but the string fits through the hole at the base of the bridge. I tried a .130 but it wouldn't go through. I like a .130 B string. I've used it on some other basses and prefer it. I'm wondering how to enlarge the hole? I don't want to change the bridge so does anyone have any advice? Thanks in advance!
  2. RSBBass


    Jun 11, 2011
    First, I would hope you don't need to be told this but take the bridge off the bass before you work on it.

    After that it depends on what you have available. The point to keep in mind is that you are going to want the hole to be smooth, particularly on the end where the string leaves the hole going to the saddle. If you are not missing by much, you could use a rat tail file and some elbow grease followed by some carborundum paper to smooth things out. If you have access to a drill press that would be the way to go. i would shy away from using an electric drill even with the bridge well clamped. Unless you don't mind a sloppy hole, it would be difficult to get a straight hole with a hand drill.
  3. 96tbird

    96tbird PLEASE STAND BY Supporting Member

    Unscrew the bridge and drill it bigger. It's probably 1/8" (.125")
    so a 5/32" (.15625") drill will do it.

    Screw it temporarily to a scrap of board or your dining room table ( :p ) to hold it while you drill.
  4. Turnaround

    Turnaround Commercial User

    May 6, 2004
    Toronto Canada
    Independent Instrument Technician, and Contractor to Club Bass and Guitar - Toronto
    Re-drilling a hole with a larger bit can be a bit tricky. If the drill bit doesn't grab yanking your wrist suddenly (as it often does), the drill chatters going in resulting in a sloppy, irregular and ragged hole. The preferred method is to use a tapered reamer which will avoid these problems.

    But you may get lucky with just the larger bit size. I'm sure you will get a lot of comments on this post saying "I just used a larger bit and it worked fine". It might. Take your chances if so inclined.
  5. Or if you have a dremel with a cone-shaped grinding stone?
  6. Thanks for the replies, everyone! I don't have access to a drill press or even a dremel. I wouldn't feel comfortable using a hand drill. Is this something most experienced repair shops or luthiers do?
  7. Yes, any luthier could do the job very easily. Make sure to take the new string with you.

    I've done them before myself, but I have a large drill bit set with fractional, numbered, and letter size bits, so it was easy to make sure I was enlarging the hole as little as possible. Mine was brass, and brass is VERY easy to do this on, and really easy to chamfer the hole.

    Personally, I did it with the bridge on the body, but how easy that is varies with the bridge, the body, and the length of your bits. Some bridge designs make it difficult to chamfer the neck side of the hole.
  8. Zooberwerx

    Zooberwerx Gold Supporting Member

    Dec 21, 2002
    Virginia Beach, VA
    If I don't have something in my Dremel kit that would do the job, I quit.

  9. Hopkins

    Hopkins Supporting Member Commercial User

    Nov 17, 2010
    Houston Tx
    Owner/Builder @Hopkins Guitars
    Put the bridge in a vice with some wooden cauls so you dont mar the finish. Then drill it out with a slightly larger drill bit. Its pretty soft metal. Just use a little oil and soft pressure when drilling it out. Its an easy job.
  10. ArtechnikA

    ArtechnikA I endorsed a check once... Gold Supporting Member

    Feb 24, 2013
    I can't imagine living without a Dremel, but I tinker with a lot of stuff...

    For a smooth precision hole, it's hard to beat a reamer. It's what they're for.

    For instance:

    That page is hand reamers - no power tools required.
    You will need a tap wrench to hold it - there's a link.
    I'd get a countersink too, just to chamfer the entry and exit.

    A 4mm reamer (closest to 5/32") will set you back about $60, plus the tap wrench and the countersink. All that's probably more than you'd spend for a Dremel, but you'd get a very high-quality hole...
  11. LOL are we still talking about reaming and drilling?
  12. Ric5

    Ric5 Supporting Member Commercial User

    Jan 29, 2008
    I convert 4 string Rickenbackers to 5 string basses.
    How do I enlarge the bridge's string hole?


    I have done it many times with an electric drill
  13. 96tbird

    96tbird PLEASE STAND BY Supporting Member

    If you're that worried about the task of drilling a hole, don't. And you don't need a $60 reamer to get a "quality hole" whatever that means. Just let the bit do the work, gentle pressure, work piece well stabilized and firm grip. You'll get some fine quality hole.

    Nobody's going to be staring at and critiquing your hole.

    Best thread ever. ;)
  14. Hopkins

    Hopkins Supporting Member Commercial User

    Nov 17, 2010
    Houston Tx
    Owner/Builder @Hopkins Guitars
    Common sense and comedic value. The best post in the thread so far. Except for mine of course:D
  15. ArtechnikA

    ArtechnikA I endorsed a check once... Gold Supporting Member

    Feb 24, 2013
    Of course not.
    However - OP said he didn't have any power tools and presumptively didn't want any.

    If you want a 'nice' (as opposed to ragged and ugly) hole made by hand, reamer is the way to go. You can do it all by hand - but it'll cost you - nobody does it that way...

    Pointing out the cost was my subtle way of saying "just go buy a power drill..."
  16. I have access to a power drill, I just don't trust my (lack of) skill. If I were to go that way, just buy one if those reamer bits?
  17. john m

    john m Supporting Member

    Jan 15, 2006
    Remove bridge, screw it to a scrap piece of wood,

    Clamp wood to drill press table (or bench if you don't have a drill press, drill hole with your diameter of choice.

    To keep the drill from "pulling in", wrap the drill with electrical tape, so that only about 3/8" of the tip of the drill is doing the work. Once the drill cuts through, it will bottom out on the tape.

    It's a clearance hole, not meant to be a machine fit.
  18. ArtechnikA

    ArtechnikA I endorsed a check once... Gold Supporting Member

    Feb 24, 2013
    That reamer is a hand tool - I wouldn't chuck it in a drill.

    Seriously - on the scale of Things That Are Difficult, enlarging a small hole a little bit is Really Easy. Use a variable speed drill on Really Slow. Bolt the bridge to a nice heavy chunk of something to keep it steady. Line everything up nice and square, make gentle but firm contact with the existing hole, and go slow.

    After, use a drill bit another couple of sizes bigger to lightly chamfer the enlarged hole. This -can- be done by just holding the drill bit in your fingers. You're just trying to break off the sharp edge of the new hole.

    A reamer is the preferred for making a perfect, smooth hole of exact size, for where this matters a lot. I have a few special-purpose reamers for making holes of precise size (carburetor jets). They're a super-expensive way that is rarely needed...
  19. Pilgrim

    Pilgrim Supporting Member

    Or remove bridge, go to Harbor Freight and pick up a set of small diamond files for $7.99.


    File carefully until the string passes through the hole. It's just a hole. It doesn't have to be perfect in shape, you just don't want sharp edges.

    As an aside - not directed at the OP - if you aren't willing to invest in tools, don't do work on your instrument yourself.
  20. 73jbass

    73jbass Supporting Member

    Apr 17, 2004
    Take it to a machinist and have it done right. Wont take more than a few minutes.