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Best way to ream headstock tuner holes?

Discussion in 'Hardware, Setup & Repair [BG]' started by HeavyDuty, May 17, 2011.


  1. HeavyDuty

    HeavyDuty Supporting Curmudgeon Staff Member Gold Supporting Member

    Jun 26, 2000
    Suburban Chicago, IL
    I have a set of used Hipshot Ultralites that I'd like to install on the second of my two Tacoma ABGs (I put a set on the first one years ago) - the heavy factory tuners on the second one bother me, plus I prefer the way the Ultralites work.

    The issue is that the used tuners are large post (1/2"), and the headstock is already drilled small post (3/8").

    What's the suggested way to ream out headstock tuner holes?
     
  2. Turnaround

    Turnaround Commercial User

    May 6, 2004
    Toronto Canada
    Independent Instrument Technician, and Contractor to Club Bass and Guitar - Toronto
    With a tapered reamer, ream out from each side of the headstock until the diameter at the surface is exactly 1/2". Because of the taper of the reamer it will leave the centre of the hole undersized so you then use a 1/2" bit to drill out the centre. Spur bits or forstner bits are best for this.

    The other option is to temporarily plug the hole and redrill with a 1/2" bit. I find the first option much easier though.
     
  3. 202dy

    202dy Supporting Member

    Sep 26, 2006
    There are several ways to approach this depending on the amount of time and the tooling available to the operator. Here are two relatively safe ways to go about it.


    Drill press method:

    1. Cut 3/8" dowel rod to fit existing holes.
    2. Option: Cut plugs to fit holes.
    3. Glue plugs into holes.
    4. When glue has cured, clamp neck to drill press on suitable backer to prevent tear out.
    5. Bore new hole for tuner.
    6. Repeat location and clamping sequence for each hole.

    Notes: This is exacting finish work. Care should be taken during layout to locate the centers of the new holes. Use either a brad point or Forstner bit. Regular twist drills will wander. Center punch the layout mark on the plug to help locating the bit before clamping. Plugs are better than dowel rods because the grain runs perpendicular to the bit. The grain in the dowel plug runs parallel and has a tendency to cause the bit to run off course. However, if care is taken it won't be much of a problem. Using a hardwood backer board beneath the headstock will help to prevent tear out.

    Low tech method:

    1. Clamp neck into vise or to the bench
    2. Using a half inch diameter tapered reamer, ream existing hole from the rear to the front.
    3. Stop reaming before penetrating the front.
    4. Ream from the front to the rear.
    5. Penetrate through the hole.
    6. Repeat for each hole.

    Notes: The hard part about using a hand reamer is maintaining a straight line through the hole. If a visual aid, like a machinists square or a simple horizontal or vertical line on the wall depending on how the workpiece is mounted will make it easier to stay on line. It is important to use the reamer on both sides for the same reason as using a hardwood backer board when using the drill press to bore a new hole. Even with a reamer there some significant tear out can happen. When both sides have been reamed, pass the reamer through the hole several times to make sure the hole is clean and round.

    There are other ways to accomplish this task. These are two of the safest.

    Respectfully submitted.
     
  4. 202dy

    202dy Supporting Member

    Sep 26, 2006
    Redundancy is what happens when the phone rings in mid post.

    Sorry.
     
  5. Turnaround

    Turnaround Commercial User

    May 6, 2004
    Toronto Canada
    Independent Instrument Technician, and Contractor to Club Bass and Guitar - Toronto
    At least we agree on the methods. And you know, two techs are better than one!
     
  6. HeavyDuty

    HeavyDuty Supporting Curmudgeon Staff Member Gold Supporting Member

    Jun 26, 2000
    Suburban Chicago, IL
    Thanks guys!

    I assume you're talking about one of those stepped reamers I've seen?
     
  7. 202dy

    202dy Supporting Member

    Sep 26, 2006
    Stepped reamers are great tools. They come in handy for some jobs.

    A tapered reamer is the one for this job. The semi-fluted reamer cuts smoother and tends to stay on track better than the inexpensive hardware store variety. However, the cheap reamer is usually 1/2" diameter at it's greatest diameter. That makes for less clean up work in achieving a cylindrical hole.
     
  8. I got very tired of hand reaming tuner holes to enlarge them; took too much time, made my wrists sore and resulted in less than ideal holes. I moved on to using a step drill bit as described below. This method took less than 15 minutes to complete the enlargements.

    enlarging_01.

    enlarging_02.

    enlarging_03.
     
  9. HeavyDuty

    HeavyDuty Supporting Curmudgeon Staff Member Gold Supporting Member

    Jun 26, 2000
    Suburban Chicago, IL
    The step drill is what I was thinking of. I'm going to give my local luthier a call to see what he'd want to do it before I go buying tools.

    Thanks, all!
     
  10. JLS

    JLS

    Sep 12, 2008
    Emeryville, Ca
    I setup & repair guitars & basses
     

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