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How to? Align, mark, and drill the bridge on a new undrilled body?

Discussion in 'Luthier's Corner' started by Flux Jetson, Aug 26, 2012.

  1. I'm thinking about using a Mighty Mite J body for some testing and developing of new bass guitar ideas. I see they come pre-routed but the bridge mounting holes are not drilled, so I'll have to take care of that. I've done nearly a dozen Warmoths so far, but I've always wussed-out and had them predrilled for the bridge ... so essentially each one was about turning a screwdriver and not much else. So I need some guidance on this so I don't mess it up.

    X-Axis: I would guess that Left/Right alignment is no more difficult than drawing a centerline on the body and centering the bridge with that, then marking and drilling. Probably tape off the center of the body so the marks don't end up on the wood. Is this even close to being correct?

    Y-Axis, 34 inch scale: Ok, well and good. But -- how do I determnine the Y position? Is it just a matter of measuring 17 inches from fret 12 (or 34 inches from the nut) and sortof eyeballing the saddles across an X-axis mark on the body drawn at 34 (17) inches? Do I put the saddles at the center of their available travel, then eye-align them with the 34 (17) inch mark?

    I'm just totally guessing at this.

    I plan on using an "easy" bridge, something that only requires a few mounting holes with no routing involved. I think they're called "flat bridge" or something like that? Perhaps a Hipshot or a Gotoh, maybe a Schaller. I still need to check out the better flat bridges yet.

    WOA! We just had an Earthquake - about a 30 second long "roller". It's still kinda rolling a little. Damn I hate those blasted things! Reminds one that humans are just fleas on the back of a giant dog named Earth. HA! There's an after shock ... friggin creepy things!

    So anyhow, does it go something along that method? Align the X axis position of the bridge with a centerline down the length of the body and center the bridge on that, then mark the Y axis position line at 34" and align the "averaged" saddles with that? Mark holes, and drill?

    Background: Obviously I'm no kinda luthier or even really much of a wood guy. I'm more of a metal worker - home shop with lathe, mill, drill presses, MIG, TIG, that sortof stuff. Was taught "hacksaw and flat file" long before I ever laid hands on power equipment - so my layout skills are so-so.

    Thank you. Any guidance is bound to teach me something and I'm very open to learning new techniques.

  2. Musiclogic

    Musiclogic Commercial User

    Aug 6, 2005
    Southwest Michigan
    Owner/Builder: HJC Customs USA, The Cool Lute, C G O
    Here is the easiest way without technically overthinking it. Mark the center of the neck pocket, mark the center of each pickup, and connect the dots...you now have your centerline. If you have your neck, bolt it in place, measure 34" from the front edge of the nut,(if this is the scale you are using) and mark this point. draw a line(that extends to both sides about 2.5") at the 34"mark, at 90 degrees to the centerline. This is your scale line, set your saddles on your bridge at 1/8" less than fully extended, and align on center so the saddles align with the 34" line on both sides. drill your center screw hole, and place your bridge, once the test unit is assembled, you can tweak the bridge for perfect alignment, and add the other screws to lock the bridge in place....Or

    mark the centerline, place the neck and run 2 straight edges down each side of the fretboard, mark these 2 lines, then find the center at 34"(or the chosen scale)between these 2 lines, and place bridge.
  3. OK, so your first method is exactly what I said to do. Cool! Hey, I got one right for once!! HA!

    I like method 1 better than method 2. Less fumbling.

    Thank you.

  4. Big B.

    Big B.

    Dec 31, 2007
    Austin, TX
    For what it's worth I actually like method two as it allows to set your bridge to the center of the full length of the neck and not the body.
  5. Only problem I can see is that method assumes the neck is mounted straight. It if is off a few degrees (which bolt ons can move around a little) then the bridge is not put in the right place. The strings may not properly align over the pickup poles, even if it is just off by a few hundreths. It seems like it's a less than optimal way of doing it. That's why I prefer the centerline reference method. It just seems like better workmanship that is based on more reliable references.

    If the bridge is mounted using the centerline of the neck pocket and pickup routs, then aligning the neck will be more precise by using the strings as references (move the neck a little until the strings are centered on the neck). That way everything (the bridge and the neck alignment)
    is based on the centerline of the body. Which is what everything else is already indexed from in the first place (neck pocket and pickup routs). May as well use the same reference as everything else does to keep with some level of continuity.

    The second method doesn't give you anything stable to establish your "cornerstone" on. You're mounting the bridge using the neck as the reference, when you don't know if the neck is even properly aligned on the body center or properly seated in it's pocket.

    It just seems like basing everything from the body's centerline, using it as the "waterline", makes more solid layout sense. Uh .. from my completely inexperienced point of view.
  6. Big B.

    Big B.

    Dec 31, 2007
    Austin, TX
    The problem is that the centerline of the neck is the centerline of your strings. I would rather be slightly off from the pickup holes than the strings themselves. In the event that your neck doesnt align with the body you've got bigger issues than placing your bridge.

    If it were me I would use both methods and compare the results. Both methods should find the same centerline and if not I would make adjustments until it were so.
  7. JIO

    JIO Gold Supporting Member Commercial User

    Jun 30, 2010
    Oceana (Pacifica) CA
    musician/artist/owner - Gildaxe
    If using single string bridge units, once you have a determined centerline and scale length, you can use household sting (not a bass string) to set the exact location for the E & G (of a four-string) and space the A & D accordingly (even only by sight/what looks right).
  8. Musiclogic

    Musiclogic Commercial User

    Aug 6, 2005
    Southwest Michigan
    Owner/Builder: HJC Customs USA, The Cool Lute, C G O
  9. xaxxat

    xaxxat Supporting Member

    Oct 31, 2008
    Shoot a laser line down the center of the neck and bridge to line them up.


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