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Thread: Question: creating a compound radius on a fretboard?

  1. #1
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    Charlotte, NC
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    Question: creating a compound radius on a fretboard?

    Iíve been toying with the idea of trying to build my own guitar from scratch with some cheap wood as a trial so I can see where itíd just be easier for me to buy decently partsÖOne thing Iíve been mentally struggling with is the compound radius needed for the fretboard. Iíve read where it needs to be a 10Ē radius on one end, and a 16Ē radius on the other end. I canít figure out a repeatable way to do this.
    My least bad thought so far is to make a jig from 2◊6s, where it follows the needed compound radius and has a slot cut it I need for my blank to rest. The new I could just hand plane and scrape and sand the fretboard to follow the jigs arc.
    Is there a better way, or a jig on the market, or a tool for this?
    Has anyone done their own compounds radius fretboard before? How?
    Thanks for any guidance here.
    http://famousartisan.com

  2. #2
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    Quote Originally Posted by Brian Famous View Post
    Iíve been toying with the idea of trying to build my own guitar from scratch with some cheap wood as a trial so I can see where itíd just be easier for me to buy decently partsÖOne thing Iíve been mentally struggling with is the compound radius needed for the fretboard. Iíve read where it needs to be a 10Ē radius on one end, and a 16Ē radius on the other end. I canít figure out a repeatable way to do this.
    My least bad thought so far is to make a jig from 2◊6s, where it follows the needed compound radius and has a slot cut it I need for my blank to rest. The new I could just hand plane and scrape and sand the fretboard to follow the jigs arc.
    Is there a better way, or a jig on the market, or a tool for this?
    Has anyone done their own compounds radius fretboard before? How?
    Thanks for any guidance here.
    I personally haven't made one. I thought they were usually done by hand with scrapers and planes but I see this guy used a router:
    https://www.youtube.com/watch?v=ZtNtgN3eXpE

    I found this nice explanation on the StewMac web site, a fun place to browse:
    http://www.stewmac.com/How-To/Online...Explained.html

    JKJ

  3. #3
    If you are just building one guitar, and if you are decent with hand tools, the far easiest and least error-prone way to do it is with a hand plane.

    The jigs for just cutting a constant radius with a router or a sander are complicated enough. The complications go into high gear when you start trying to jig up for a compound radius. You should try to avoid all of that unless you are jigging up for production work.

    The best explanation on how to do it with a hand plane is in the Cumpiano & Natelson book on building acoustic guitars. Follow that procedure and you will be fine.

    The real trick with a compound radius fingerboard is to not get too hung up on the specific radii. You want a comfortable radius at the nut, and you want the fingerboard to be absolutely flat under the run of each string. Since the fingerboard gets wider as you approach the bridge, that means the radius will be larger on that end than it was at the nut. You can do the math to determine what that second radius is, but why bother, if you are using a hand plane to get there? It will be whatever it will be, given the radius at the nut, and the widening of the fingerboard, and the absolute that you need the run under each string to be flat.

  4. #4
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    I never thought about the router approach. I haven't watched the video yet (going to do that shortly), but my initial thought is much like a router setup for planing a large slab.

    Definitely going to check out the article on Stew Mac.

  5. #5
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    Feb 2018
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    Charlotte, NC
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    Don,
    Thanks for the lead on that book. The more resources I can read the better...
    And I doubt I'll be doing production level output, but my mindset is kind of I want to practice it about a dozen times on some reclaimed HT oak pallet boards I have laying around. I want to be at the point where it's a repeatable process for me so that I am fairly confident I won't mess up my final product (including fret layout).

    And your entire last paragraph is an enlightening way for me to think about it. Makes a lot of sense when put into non numerical terms... Thanks!

  6. #6
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    Plano, Texas
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    Save yourself a ton of trouble. Buy your fretboard already radiused and slotted from LMII. FWIW, as a very long time player, I personally don't care for really extreme compound radiuses, but that is just me.

  7. #7
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    Feb 2018
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    Wow. So you supply the board, pay $18, and they radius and slot for frets? That's almost unbeatable of a deal...

  8. #8
    Actually, I think LMII would want to sell you the wood. But, you can ask . . .

    The router methods of radiusing fingerboards all need to work with absolutely no slop, or else the fingerboard turns out pretty imperfect, which means you will have wasted your effort and the wood. Like I said above, unless you plan on building lot of guitars, the jigging up for this particular task is work you really should not take on, as it will feel like a disproportionate time suck. Either buy pre-made or do it by hand. Some jigging up for guitar building is easy and a bit fun. This particular task is harder than most to properly jig up for, and the tolerances have to be insanely tight.

  9. #9
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    Feb 2018
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    Oh, duh. I see that on their website now... More to think about on this one.

    For now, I think I'm going to focus on the body and building a jig for molding that. Then I'll come back to thinking about the neck and fingerboard...

    Thanks for all of the help and thoughts!

  10. #10
    No worries. In case you do decide to do this yourself, let me share the most precise way to get a compound radius without routing or sanding jigs or fixtures, if the hand plane method is not a good fit for you. This is not as inexpensive as using a hand plane you already own, but a lot of professionals do it this way, it is not crazy expensive, and you will have what you need to do hundreds of fingerboards.

    StewMac sells these aluminum sanding bars that have a constant radius machined into them. Buy one of these with the radius you want at the nut. Also buy some StickIt sandpaper, about 3" wide. Also buy (or create) a steel bar, about 18" long, about 1" thick, with an edge machined absolutely flat.

    You stick some sandpaper on the radiused sanding bar, and sand a constant radius into your fingerboard. Then, you stick some sandpaper on the steel bar and sand along the run of each string, first riding along one edge of the fingerboard, then the other edge, then eyeballing it in the middle. This creates a compound radius fingerboard.

  11. #11
    Dude! Forget LMII, try Randy Allen guitars. He's cheaper, does good work, and has some preslotted stuff.

    I'm still annoyed at LMII for not telling me that they don't sell their slotted fretboards pre-thicknessed. On guitar 2, I bought a fully serviced kit from them and didn't know that...and the fretboard was about $60!

    The Allen guitar fretboards were ready to go and about $20-$30 each.
    Only downside is that you only have rosewood or ebony.

    For the compound radius, the hand plane method is the easiest way to do it.
    Just make sure that your plane is very sharp.
    The LV Hong Kong Trim planes ($30) would be the cheapest good planes up to the task.
    The PMV11 block plane would be even better.

  12. #12
    Check out the grizzly g0577 fretboard radius sander. Too expensive for a single or even a few fretboards but it may give you an idea or two.

    A cnc may do the job also.

    clint

  13. #13
    I don't think a router jig to do that would be expensive or two difficult, having made jigs to machine cylinders, but if you are only making one guitar then I'd agree it may not be worth it. If anyone is interested in building one I could tell you how to do that.

  14. #14
    Quote Originally Posted by Brian Famous View Post
    Iíve been toying with the idea of trying to build my own guitar from scratch with some cheap wood as a trial so I can see where itíd just be easier for me to buy decently partsÖOne thing Iíve been mentally struggling with is the compound radius needed for the fretboard. Iíve read where it needs to be a 10Ē radius on one end, and a 16Ē radius on the other end. I canít figure out a repeatable way to do this.
    My least bad thought so far is to make a jig from 2◊6s, where it follows the needed compound radius and has a slot cut it I need for my blank to rest. The new I could just hand plane and scrape and sand the fretboard to follow the jigs arc.
    Is there a better way, or a jig on the market, or a tool for this?
    Has anyone done their own compounds radius fretboard before? How?
    Thanks for any guidance here.
    You don't need to have a compound radius. Many, if not most, guitars have a simple radius.

  15. #15
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    Way back in the 1950'5 and in the 60's when I was very active in making modern guitars,(before Colonial Williamsburg snapped me up,and sent me back 200 years!), I used to automatically make compound radius fingerboards. I just planed an even width angle on each side of a fingerboard blank which was already tapered to fit the neck. Then,I'd take the corners off of these angles with a shallower angle,dividing the surface of the fingerboard into 5 surfaces. Hopefully you see what I mean. a bit of rounding over with sand paper completed the curved,compound angled surface of the fingerboard. All I used was a sharp block plane,a Stanley. I had many times fewer tools back then. The Stanley did fine if sharp enough.
    This was way before I knew about places to buy guitar parts such as fingerboards,etc. I only bought tuners and binding material from Gibson. I got away with that because one of their traveling reps had made me a factory authorized repairman. Jerome Zoeller was his name. I also knew a rep from Guild named Herb Sunshine !!!

    I'm going to stick my neck out and say that I think that a certain famous maker who worked on Kenmore St. in New York made his fingerboards the same way. D'Angelico was that builder,of course. I have been able to examine some of his instruments closely while repairing them over the years. I also did a complete top-off rebuild of a Stromberg once. Those were my years of working nearly only modern guitars,though in the late 60's I built some lutes and a 16th C. Italian harpsichord. This last was what Williamsburg heard about and wanted me to make a harpsichord (18th. C. English) for the Music Teacher's Shop they were soon to open. They did not want to actually hire a builder due to scanty historical evidence, but did when they saw my work. That lasted 40 years.
    But,I ramble. A friend had a new Strat several years ago which did not have a compound fingerboard. He liked to slur notes sideways,and every time he did so in the upper end of the fingerboard,the string would touch the fret above it,and buzz. My only cheap and quick fix for that was to file the center portion of the upper frets more in their centers than in near their ends,making a compound fingerboard out of them,which solved the problem. I thoroughly recommend the compound fingerboard.
    Making your own compound fingerboard with a plane like I did (and still would!) takes a little skill,but not a great amount. If you don't keep the bevels nice and straight and equally flat everywhere,you will find you have a buzzy instrument when you string it up. The only quick cure would be to make the strings inordinately high. The real cure would end up having you remove the frets and having to plane both wood and pearl. Then,perhaps a straight sanding board with 80 grit paper tightly glued to it,and about 12" long would be helpful. So,be accurate and careful !

    I have a Grizzly side stroke sander,but I think I'd trust my old method better Just how flat is their graphite cloth covered platen?
    Last edited by george wilson; 11-10-2018 at 5:53 PM.

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