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Laying out a fan fret

Discussion in 'Luthier's Corner' started by Nelson Guitars, Mar 14, 2008.


  1. Nelson Guitars

    Nelson Guitars

    Aug 14, 2006
    Novato California
    Custom builder
    I am beginning a commission for a 6 string fan fret bass and to start I needed to do some layouts of various fan arrangements.

    Accuracy is central to any fret spacing so a few weeks ago I put a bid in for a 40" vernier caliper on Ebay. Lost that one but did win a 24". Biggest caliper I think I'll ever really need. I clamped a stop block square to the card stock I will use later to make the various fan options. Using that I marked the head of the vernier to indicate the nut location and then laid out the fret locations using a razor blade. I really prefer a knife cut to even the finest pencil line when it comes to critical layout. All layout is done from the nut to each fret and not from one fret to the next. It cuts down on potential errors building on one another.

    fanlayout1.

    I laid out the two outer string scale lengths and drilled through with a bit the same size as sewing pin. I then laid out the string spread on another piece of card stock and transferred the fret locations by using the pins again. Tapping the pins in with my little hammer felt eerily like what my acupuncturist did with similar pins in my back. At this point I did a quick check of my spacing with a small caliper and verified the fret to fret spacing just to be sure I did not make some sort of error in the original layout. Measure twice, cut once!

    fanlayout2.

    After locating the outer fret locations it is a simple matter of connecting the dots. I used a steel ruler for this and made sure to stay to the same side of the pins every time. None of this is rocket science but it is exacting even though it is just for deciding what sort of fan will be best. I may change scale lengths or the relationship between the two scales. I don't know yet, but when I do I will go through a similar process to create the jig to actually make the cuts for the fret kerfs. Lot's of thoughts on that process, but that will have to come in it's own time.

    So far I have made three templates with the same scale only with the perpendicular fret at the 5, 7 and 9. Now I have to get my client to try these layouts on an existing instrument and tell me which feels best to him.

    variousfans.

    Greg N
     
  2. hmm, so you use a formula to calculate how long the scale length should be for the high and low string? I would love to try one of these fanned fret basses, have not had the opportunity yet.
     
  3. Dirk Diggler

    Dirk Diggler Supporting Member

    Mar 3, 2004
    Anytown USA
    Hey Greg,
    Very interesting technique. I love seeing how other people do things, always makes me rethink my own techniques.
    Great hint on the blade, I use an inlay scribe, you don't want to use a pencil to mark them for sure. :)
    Thanks for sharing.
    Dirk
     
  4. Nelson Guitars

    Nelson Guitars

    Aug 14, 2006
    Novato California
    Custom builder
    I feel the same way.

    This was just what I came up with on the fly using process' developed over years of working with wood. I would be very interested to hear how you accomplish this task as well. CNC seems to be what most people would depend on for this sort of task these days. Guess I'm just old school.

    Next step will be deciding whether to cut these by hand or modify my existing fret kerfing jig to do it under power.

    newfrettingsaw2.

    Greg N
     
  5. Nelson Guitars

    Nelson Guitars

    Aug 14, 2006
    Novato California
    Custom builder
    Yes and no. Pilot Jones was kind enough to share a rather sophisticated spread sheet that helped me to understand in a mathematical way the range of string sizes and scale lengths under various tensions that will produce a given note. Change one thing and the others change as well. So now I have a limited number of options I find mathematically acceptable.

    While the formulas did narrow the options for me, mentally I am the sort who must bench test such theories to truly believe them. I have a string testing rig I set up many years ago that I have now dusted off and will use to some degree to add to my knowledge/understanding before committing to a certain fan or scale length. The range of acceptable string sizes and scale lengths are highly subjective and I have to try and understand the players preferences as well, not just what the numbers say. We are both shooting in the dark to some degree since tension, action and string size all affect the "playability" of the instrument.

    The variables could drive some people crazy. The need to "know" that it is "correct" in all aspects before starting. The old adage about the bird and the centipede comes to mind. Sometimes you just have to move forward with what comes naturally and not over think things. I am getting there. Slowly, but getting there.

    Greg N
     
  6. Dirk Diggler

    Dirk Diggler Supporting Member

    Mar 3, 2004
    Anytown USA
    Hey Greg,
    Well as far as cutting for frets, I layout with tape on the board. I use a Stew Mac thin blade mounted in a fairly cheap sliding miter saw, luckily it does have a laser. The first cut depth is a little dicey until it's set but the rest go fairly easily. I opted for machine after hand cutting my first Ziricote fingerboard. :)
    Dirk
     
  7. Greg,
    Be interesed to hear what your spacing steps are string-to-string. Novax (or Dingwall) recommend 3/4" is optimum for string response/tension/pitch, for me that felt a little too fanned for my first attempt and I scaled it back to 1/2" interval per string.
     
  8. Nelson Guitars

    Nelson Guitars

    Aug 14, 2006
    Novato California
    Custom builder
    I will be interested to know that too. :smug: Right now the layout is .8" per string. A little more than you mention and it seems like that might be a lot.

    Still working this out.

    Greg N
     
  9. SDB Guitars

    SDB Guitars Commercial User

    Jul 2, 2007
    Coeur d'Alene, ID
    Shawn Ball - Owner, SDB Guitars
    Greg -

    You might check this out:

    http://www.fretfind.ekips.org/2d/

    This allows you to print an accurate template using basically any computer, for either standard or non-parallel fretted instruments (multi-scale... like Fanned-FretĀ®™ :))

    The "non-parallel" version can be directly linked here:

    http://www.fretfind.ekips.org/2d/nonparallel.php

    It lets you set which scales you want for each outer string, how much fretboard width you want beyond your string width, and what fret you want as parallel (which mostly determines the playability near the nut... for .75" per string scale differentiation, I like to set the 6th or 7th fret as parallel. Moving that to a lower fret makes it "easier" (a relative term, I think, when it comes to playing on fanned frets) to play below the 5th fret, but much harder to play above the 7th fret...

    In this example, it is the 7th fret... I find it very comfortable to play, and that's something I rarely say about a 6-string bass... also, this is 37" - 33.25", which amounts to the afore-mentioned .75" differentiation:

    [​IMG]
     
  10. Arx

    Arx

    Jan 22, 2008
    I'm doing an 940mm -> 840mm fan on the 5 string I'm building. roughly 37->33 It is a very wide neck though, comparable to most 6 strings.

    The frets are done, and don't feel too extreme, as far as angles go. The only thing that's a bit scary is the length of the first couple frets at a 37" scale. It'll definitely mean moving my hand to jump from first to fourth fret.

    Now I just need to build the rest of the bass.

    The parallel fret is an important choice for sure, though. When I did the math, I ended up with less angle at the nut than Dirk's basses, even though I've got less strings and (if I'm remembering correctly) a wider fan. His are parallel at 12, mine is at 7

    His is probably way nicer to play way up the neck though, where mine will get a little odd. I don't really play up the neck much, so 7th fret suits me better. If I did, I'd parallel it higher up. If I really stuck to the bottom end, I'd go with the 5th or something. It would make the angle a lot less weird at the nut, but the top end of the fretboard will end up pretty useless and the bridge angle will be a bit silly.
     
  11. Hi, I'm in the process of building a 5-string with a fan-fret system and I went with a 36" scale on my B string. I was going to use a 34" for the G string, but from what I heard above that might be a mistake. After laying it out my 12th fret was the 90degree fret. And I do a lot of playing in that area. If I use the .75 difference between strings, wont that make the G string too short? (32")I've been playing 5-strings for a few years now and wasnt happy with the B string on any of them-hence the move to 36". but I'm not sure now, what to do on the G side.


    BTW I'm blogging my build at dreamsofluthierie.blogspot.com
     
  12. Arx

    Arx

    Jan 22, 2008
    Note: These are my impressions from my test dtawings, and from fiddling with the neck for my in-progress bass. I haven't actually played one yet.

    If you want it parallel at the 12th fret, you'll probably want to go with a more subtle fan, or you'll end up with quite a steep angle at the nut. Your original plan may be good for that. If you like the way a 34" G sounds, you don't necessarily need to mess with it. The .75" just seems to be a rule of thumb that will give you a fairly even tension on all of your strings, and not be too wild to play. Fanning to a lesser degree your high strings will still be tighter than your low ones, but not to the same extent as on a normal fretboard.

    My neck has a 1" per string fan, and it feels like it should be pretty playable when I'm done. It's a wide neck though, so the angles are less steep for a given fan rate. It's about 37" to 33" (I used metric) with a parallel 7th fret.
     
  13. I was thinking that if I did do a 36-34 I would offset the first fret by an inch, and the bridge slightly more due to compensation. Do you think this is too much? Yes, my G D A & E strings sound fine, its my B that I'm trying to fix. So you think I'll be fine with less than a .75 step between scales? I would really hate to get it built and be disapointed.
     
  14. Arx

    Arx

    Jan 22, 2008
    Well, It'll certainly be tighter than it will be on a 34" or 35". Tight enough is subjective.

    As far as the offset goes, keep your compensation seperate from your fan. Offsetting the bridge more is just making a longer scale. You need to draw your frets based on the exact scale length you want (no saddle compensation), and then the bridge will move back from that point to compensate. I'm assuming your bridges have a compensation adjustment, so you'll want them positioned so that when they're adjusted almost all the way out, they're at the true scale length. The last thing you want to do is build in more compensation than you need, and not be able to adjust far enough.

    I sure hope your offset isn't too much, since mine is considerably more than an inch at the nut, and more like 3 inches at the bridge.

    Print yourself a scale drawing and look. If you use the fretfind site, it'll generate it all for you. You can experiment with different parallel frets too. You can move it to the 9th or 7th if you want it more normal in the bottom register, or leave it at 12 if you want the upper register to stay a little less slanty.

    -Nick
     
  15. SDB Guitars

    SDB Guitars Commercial User

    Jul 2, 2007
    Coeur d'Alene, ID
    Shawn Ball - Owner, SDB Guitars
    I would not recommend a 12th fret offset unless you have less than a 1.75" scale differentiation, and even then I'd probabluy offset around the 9th or 10th fret. Low stirng playablility is more important at the nut than at the 24th fret, as most people only play the higher strings above the 15th fret, anyway...
     
  16. Kennethfaria

    Kennethfaria Banned

    Mar 12, 2008
    noob question, brace yourself:

    what exactly are the advantages of fanned frets? Disadvantages?
     
  17. Arx

    Arx

    Jan 22, 2008
    Yeah. That probably pretty much explains it. More even tension on the strings. It'll give you a little tighter bottom strings, and a little less stiff top strings. Potentially more ergonomic, depending how extreme the fan is.
    It looks cool too IMO.
     
  18. Kennethfaria

    Kennethfaria Banned

    Mar 12, 2008
    makes sense i find that whenever i string my fingers to play notes that are spread apart i get that diagonal shaped finger.
     
  19. I just layed it out in full scale and even tho I offset 1" at the nut, it doesnt seem to effect the playability. Because of distance between the frets at that end of the neck, you can finger the strings straight up because the bottom of the first fret doesnt overlap the second fret. Actually, looking at it, none of the frets overlap all the way to the 24th fret (although it gets real close).
     

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