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Dead Spots on Acoustic Fretless

Discussion in 'Hardware, Setup & Repair [BG]' started by kirkdickinson, Feb 27, 2013.


  1. kirkdickinson

    kirkdickinson Supporting Member

    I have a Michael Kelly Dragonfly - 5 String Fretless . I got it back in November of 2012.

    I really like this bass and the sound, but it has gotten a couple of dead spots on the neck. D string at 13, (Eb) and 15 (F) are unusable. It buzzes out like it is hitting the neck somewhere else no note can be sounded at those positions. There are a couple other places where it buzzes a little, but the notes sound. I took the bass back to the shop where I bought it. The guy told me that their was a little rise in the neck after where it joined the body. Fret 16-20 area. They told me that it was really dry this time of year and that I needed to have a humidifier in the case with it. I bought one. He told me that in a week or so, hopefully it will be ok. Been in there a week and no change.

    I can look down the neck and see a little rise there.

    With my electric basses, I usually do all my own setup work. I have feeler gauges and all the allen wrenches. I have turned the truss rod 1/4 turn to give it more relief and that didn't help, I have gone back the other way, that didn't help. Most of my electrics are set with almost straight necks and relief so small that it is difficult to measure. That is how I usually like them. But this is a different animal and I don't know much about ABG.

    The guy at the music store told me he could shim the bridge, but I don't think that is a good solution. I think the action is too high overall already.

    I can take measurements on action and relief if that will help diagnose this. Or if I need to take is somewhere else to have it looked at I can.

    Thanks,

    Kirk
     
  2. Bruce Johnson

    Bruce Johnson Commercial User

    Feb 4, 2011
    Fillmore, CA
    Professional Luthier
    Not much diagnostics needed. It has a couple of little lumps in the fingerboard that need to be smoothed out. Playing around with the relief and the action isn't going to help. The fingerboard needs a light resurfacing and repolishing. Not a big deal to someone who knows how to do it. I resurfaced two Baby Bass fingerboards yesterday afternoon; about a half hour each.

    It's a common problem. As the fingerboard wood dries, it shrinks. If there are spots where there is a wave or curl in the grain, the shrinking will be uneven, leaving small bumps or dips. We Luthiers try hard to pick and machine fingerboards so that they stay perfectly flat, but there's only so much that we can do. Wood isn't perfect, and it dies slowly.

    Get the surface smoothed out and it will be fine. And it probably won't need it again.
     
  3. Low Main

    Low Main Supporting Member

    Nov 27, 2004
    Massachusetts
    I'm guessing this is a MK bass that has the fretboard inlays.

    If so, those may be playing a role. Leveling the fretboard may not only eliminate humps and dips in the board itself, but also level any areas of the inlay that are proud of or below the surface of the board.

    Maybe press on the inlay in the problem areas with a pin or a small punch to make sure it's not loose. If it is, wick in some thin CA glue and clamp it down with wax paper and a caul, then re-level the board.

    Also check nut slot height. You may want the slots higher than what they cut at the factory.

    I always wondered if playing an inlaid fretless would result in differences in tone or sustain when the strings were stopped on inlaid areas of the board as opposed to the bare wood areas.
     
  4. kirkdickinson

    kirkdickinson Supporting Member

    Thanks you guys. I played with this last night a little bit and adjusted the truss rod until the neck is almost straight. Paper think relief. The buzzing didn't improve or get worse, but my action on the rest of the strings is far improved.

    I put a capo at 1 which I do when checking relief and found the playing anywhere else on the neck has no additional buzzed or dead spots than with strings from the nut. I think this nut could actually be lowered. Pretty sure Bruce is right and a little work with a radius block could fix all my problems.

    I am not going to attempt this. It is still under manufacturers warranty, so waiting to hear back from the Michael Kelly Guy. If I have to take it somewhere and have a choice, there is a local luthier that is highly respected.

    http://www.willowtreeinstruments.com/ is his website.

    Kirk
     
  5. Bruce Johnson

    Bruce Johnson Commercial User

    Feb 4, 2011
    Fillmore, CA
    Professional Luthier
    It actually isn't difficult to resurface a fretless fingerboard yourself. Just some elbow grease and some patience.

    I don't use radius blocks. I have a set of the Stew-Mac blocks that I bought 20+ years ago, but I rarely use them for anything. My favorite tool for flattening out a fingerboard is a rigid auto body hand sander. It's basically a 9" x 2 1/2" aluminum plate with a handle on top and clips on the ends to hold the paper. I put on a sheet of 3M FreeCut 100 grit paper and go to work.

    Gently stroking it down the fingerboard, with light pressure, you can see where it is cutting away the high spots. Work right along the string paths, tilting it to follow the radius. If the ridges and lumps are really bad, I'll use a big 16" flat file to rough them down. When it's trued out, I'll work up through 220, 400, and 800 grit paper on hard rubber blocks, making sure that the scratches from the previous grit are removed. Patience and good light. Then I'll rub it down with white Scotchbrite and run it over a buffing wheel to bring it up to a shine. Then a couple of coats of Stew-Mac's Fingerboard Oil to seal it up.

    That's the magic secret process. On most necks, it takes me about a half hour. One of the Baby Bass necks I did a few days ago was a fairly new KK Bass. Nicely made, good original machining, but the ebony "grew" a couple of little bumps in the surface that were giving the owner fits. A quick resurfacing and it's fine now.
     
  6. kirkdickinson

    kirkdickinson Supporting Member

    I am going to send it to Michael Kelly. If it wasn't brand new and still under warranty, I would try it myself.

    Thanks
     
  7. kirkdickinson

    kirkdickinson Supporting Member

    Got it back Wednesday from Michael Kelly. They shaved the neck a little and raised the bridge a little. seems to have a dead flat relief, but I haven't measured it.

    Put on a set of tapewounds and am really liking it. Lost some volume acoustically. Will see how well it fits into the band with the new strings tomorrow.

    Kirk
     
  8. The problem with refinishing a fingerboard profile is keeping the neck rigidly held in some sort of jig. The neck needs supporting along its length every few inches to make sure the neck doesn't bow downwards under the hand pressure that's involved with the sanding operation. (I made my own with a piece of 3"x3" timber fitted with round top coach bolts, themselves having cork pads to prot ct the neck underside).

    Then, you'll need something that's known to be straight and true against which it you can test the neck before, during and after sanding. A 1 yard, metal 'straight edge' will almost certainly not be good enough and, in the end, I spent £120 ($150?) on a piece that was guaranteed to be true to a few microns to use as a workshop standard.

    Then you'll need some sort of radiussed sanding block of the same radius as your fingerboard. Buy a really good one because your final results will depend largely upon this tool.

    When sanding, make sure your technique is such that it reduced errors not compounds them because it's impossible to exert even hand pressure and arm movement angle over the neck length.

    This how I do it: Always sand the **WHOLE** fingerboard. 20 strokes back and forward starting at (say) the butt of the neck. Remove the sanding dust from the paper (some wood dust is a danger to respiratory health). Turn the block. 20 strokes down the neck from the nut end. Remove sanding dust and turn the block. 20 strokes from the butt end again .... and so on. Check straightness from time to time. Be prepared to work steadily, taking your time. Eventually you'll see you've sanded the nut end completely because the wood looks clean and fresh. But carry on sanding the whole fingerboard. Take a pencil and make VERY LIGHT marks across the width of the f'board from nut to butt. These are called "witness marks" and you will see them disappear as you sand giving an exact indication of where wood is being removed from the f'board.

    DISCLAIMER: I do hobby lutherie to my own instruments: I'm self taught and have never had tuition. I don't work on others' guitars and I make zero money from what I do. What I describe above seems to work for me but may not work for others.

    Best. J
     
    Last edited: Jul 10, 2017

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