Fret crowning question

Discussion in 'Hardware, Setup & Repair [BG]' started by Truktek2, Jul 13, 2013.

  1. Truktek2


    Sep 5, 2008
    Queens, NY
    I've just recently started doing my own fretwork, and I have a couple of questions. After I level the frets, I run a black marker over the fret tops so I can see how much material I take off when crowning. I stop when there is a thin line left on top of the frets.

    How thin of a line should I leave? I usually stop when I have a little under 1/64 of an inch showing (the contact area of fret that touches the string). Is this too little or too much?

    I also noticed, that it's possible to remove more material from one side of the fret than the other if you're not careful, making the black line not perfectly center on the fret. Would such a small deviation cause intonation problems?

    And lastly, how many times can this procedure be done before the frets need to be replaced? How do you know if your frets are too low?

    Thanks for all the insight. :help:
  2. Bruce Johnson

    Bruce Johnson Gold Supporting Member Commercial User

    Feb 4, 2011
    Fillmore, CA
    Professional Luthier
    You're doing the right things. I typically do the black marker trick before the leveling, because that's where you really want to be able to see where you are contacting the frets. My favorite marker for darkening the fret tops is a Sharpie Industrial, the big fat ones that they sell at Home Depot. They have a wide chisel tip that works great on a fret.

    For the crowning, you want to leave a thin line right down the center of the fret. I don't know if the width of the line matters much, just make it thin and uniform, and centered. If you crown it too much and "erase" the line, then you've damaged the leveling. So, to do a perfect job, make the line as thin as you dare without erasing it.

    If you file too much on one side, causing the line to be off center then, yes, you've moved the point where the string is contacting, messing with the intonation. Sometimes we intentionally crown frets offset to correct the intonation on an out-of-position fret. That sometimes is a problem on '60's instruments. On most modern instruments, you can assume that the slots are accurately located, so the thin line should be centered on the fret, and centered over the slot.

    I don't know if there's any solid answer to when frets are too low. Super low cut frets were a fad a while back, mostly on guitars. I guess they are too low when you can't make a crown on them any more. Or when the edges cut your fingers.
    Killed_by_Death likes this.
  3. Truktek2


    Sep 5, 2008
    Queens, NY
    Thanks for the info! I will look into that marker. It's interesting that older instruments weren't as accurate, and that you could compensate for it. I learn something new every day. I've been looking on the internet for specs, but haven't come across any. I guess it's just preference and/or feel. I'll just keep tinkering until I find what works best for me.:p