How to use adjustable bridge? Which way do I turn the adjusters?

Discussion in 'Luthier's Corner [DB]' started by CarterEddy2004, Jun 23, 2020.

  1. CarterEddy2004


    May 26, 2020
    I just got a new bass with an adjustable bridge, and the action is a bit high for my taste and have never used string height adjusters. Which way do I turn the wheels to lower my string height?
  2. One way will turn easier than the other. Turn it that way to lower the action.

    Count your turns so if you don't get the result you expect, you can put it back to where it was.
    Chris Fitzgerald likes this.
  3. bassmanbrent

    bassmanbrent Supporting Member

    Apr 5, 2011
    Vancouver, BC
    You could also put a mark on the adjuster wheels so you know where you started. Also try to make sure you adjust each wheel equally.
  4. eh_train

    eh_train Supporting Member Commercial User

    Jan 12, 2004
    Owner, Stand Up Guy Basses (Repair/Sell/Buy upright basses)
    Re "One way will turn easier than the other", that's only true if the adjusters were installed properly. A properly installed adjuster should move by hand, and not require a pair of pliers. Sometimes they're fit so tight that the adjuster won't turn in either direction, unless you loosen the strings first. Don't force the wheel, or the bridge will get out of position.

    Just noticed that you posted a week ago - were you able to get things adjusted?


    piggywiddle likes this.
  5. I would let some of the string tension off any way, say between one and two tones, to avoid wear and make turning easier.
    Tasio likes this.
  6. Calvin Marks

    Calvin Marks Supporting Member

    Oct 22, 2017
    yes I agree. I had a bridge made years ago with aluminum adjusters and the maker said to me with a smile on his face “I set the adjusters purposefully tight so they’re locked in place” I was like huh? What is the point of doing that? I kid you not! I was silly enough to actually take the bass home and then take the bridge off my instrument and take some pliers to get them to start turning.

    always move them in small increments and equally! Do not have one side higher than the other.
    Chris Fitzgerald likes this.
  7. "purposefully tight"? Tapped threads are a certain size and pitch, period. I guess if one used the wrong tap size (the difference between 1/4" and 6mm diameters is .35mm or .010", and thread pitch, 20 vs. 25/inch) in wood, the adjuster could probably be forced in and would cut its own threads. Another possibility is that the tap was not run totally through, especially in a "threads up" situation. The beginning threads of a conventional tap are undersized and tapered so the tap finds its way into the pilot hole. "Threads up" requires a blind tap that has full threads even at the end. If the holes for the non-threaded part aren't exactly concentric with the tapped holes there will be binding as well.

    Hey, it's not a bug, it's a feature.

    Under any circumstances, if you need pliers to turn an adjuster that's not bottomed out, somebody f-ed up.
    robobass likes this.
  8. Chris Fitzgerald

    Chris Fitzgerald Student of Life Staff Member Administrator Gold Supporting Member

    Oct 19, 2000
    Louisville, KY
    Some years ago, when I complained about how difficult it was to turn my adjusters, I was advised to wax up my threads with a candle. Best advice I ever got. Now they turn by hand even under extreme tension.

    For anyone new to adjusters reading this, it’s also good to mention that what moving one adjuster really does is kind of counterintuitive: if you lower the bass adjuster, you’re actually raising the E string higher off the board and lowering the G string closer to the board and vice versa. It took me years to figure this out.
    lurk and piggywiddle like this.
  9. Calvin Marks

    Calvin Marks Supporting Member

    Oct 22, 2017
    The best advice I can give you (anyone) is as soon as you get a new bass with adjusters set the adjusters to the very bottom and then take a marker and put a dot on each adjuster - it will act as a reference point for you to ensure that they're always equal. This should be standard for all basses being built IMHO!
  10. John Sprague

    John Sprague Sam Shen's US Distributor

    Mar 10, 2003
    Rochester, NY
    Sales Manager, CSC Products Inc.
    Here's how we do it. If yours don't move like this off the bass, it's likely time to call your luthier.

  11. robobass


    Aug 1, 2005
    Cologne, Germany
    Private Inventor - Bass Capos
    Mr. Badger makes a very good point about not using a bottoming tap. I have two other explanations to add. One is not using a large enough pilot drill. Many luthiers use a 3/16th" bit. This is smaller than any machinist's handbook recommends. I guess the thinking is that there will be more thread height if you under-pilot. I think that you will simply compress the wood during the tapping operation and then it expands later and makes the fit too tight. The second thing is that someone uses a plug tap instead of a taper tap to start the threads, and it doesn't cut concentric to the hole. If you don't tap with the bridge still in the fixture you used to drill the hole, then you need to start with a taper tap and then go back with either a plug or bottoming tap. If you see your guy drill the pilot holes, cut off the feet, and then put a plug tap into his screw gun, then you need to find a new guy. If the tapped hole isn't perfectly concentric to the pilot hole then there will be bending forces which will make the adjusters hard to turn, if not also constrict the sound. Fitting bridge adjusters isn't rocket science, but I think it does require more thoroughness than some luthiers appreciate.
    misterbadger likes this.