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diagnosing fingerboard curvature problems

Discussion in 'Setup & Repair [DB]' started by myrick, Apr 29, 2003.

  1. I am about to take my bass in for a major tune-up. The Luthier is well regarded, but new to me. Aside from a new bridge, and better fitting or replacement of the soundpost, I want to have the fingerboard planed and shaped a tad.

    I'm not trying to get the action waaayy down - I have it at around 8mm to 10-11mm with Obligatos and would be happy to keep it there or just a shade lower. But I know the board has some areas where the scoop is off kilter, making the playing and tone a little off on certain notes.

    I'd like to get a more accurate picture of just where the problem lies, the better to discuss things with the luthier before he sets to work. Wonder if anyone could describe a good, reasonably methodical way to more accurately assess exactly what's not right about the board right now, so I can have a useful conversation with the luthier? I have read a bit here and there, notably some interesting stuff involving chalk and straightedges in a rant on Jeff Bollbach's own website, but I was hoping for more specific "how-to" advice on diagnosis from the gang here. TIA.
  2. sean p

    sean p

    Mar 7, 2002
    eugene, oregon
    if your luthier can look at the bass when you drop it off, that's a great time to ask those questions. in my experience, guys generally examine the scoop of the board with straight edges (longer for the overall picture, shorter for particular areas on the board) and can explain fairly easily what they're looking at and how your current setup differs from the setup you may want for playing the way you want.

    in my limited experience talking to luthiers about this, it's not so much the diagnosing of a board's, shall we say, personality? and how to make that comply with the player's wishes that's difficult - it's the proper execution of the planing which follows.

    if your luthier is 'highly regarded' he'll probably have all this stuff pretty much down pat.

    good luck,
    sean p
  3. Martin Sheridan

    Martin Sheridan

    Jan 4, 2001
    Fort Madison, Iowa
    Bass Maker
    The first thing I'd do is mark all of those places with a pencil. Then when you get there you will remember all of the trouble places.
    Generally playability has to do with three things; bridge height(which you mentioned), height of the strings above the board at the nut, and the scoop in the fingerboard. Everyone has a little different way to look at this, but it comes down to what suits your playing style the best. If you primarily bow and lean a lot on the bow you may need the strings a little higher at the nut than I'd like for myself, and you may need a little more scoop and a little more height for the strings at the end of the board.
    If you don't have a true straight edge yourself to look at the scoop under the edge, you can press down with one finger(index left hand)right in front of the nut, and another at the end of the fingerboard, and if your eyes are good you might be able to see what the scoop looks like. If you've got some buzzes around D and E on the G string, look hard at this area and you'll probably see that the board is a little closer to the string in this area; a kind of bump that's causing the buzzing. If you're playing on the A string above the E and it just doesn't feel right, like you're bottoming out too soon, that whole area may need more scoop. By the same token, if your strings seem to be at about the right height, but the bass seems really hard to play; hard to press down on the strings, then there's probably too much scoop or the strings are too high at the nut.
    Finally, given a choice, take the bass to a repairer who actually plays the bass! Or, be sure to play the bass before you take it back out, and if it isn't right, get the person to do it over; right then if possible. Everything can look good with a straight edge, but the only way to know for sure is to be able to play the bass. If it's not right, get a pencil right there and mark the place(s), and look at it with him, your eyes might be better! Measurements are fine, but it all comes down to playability.

    I'm getting a lot of interruptions, my boss actually wants me to do some work! Hope I answered your question and didn't leave too much out. By the way, with a good ebony fingerboard running about $750 installed, this is not a job to try yourself.
  4. Thanks.

    Though a couple of months have gone by since I first launched this thread, I still haven't got around to this job. Will definitely try all of the above before we go to see the bass doctor.

    The bass in question I intend to be set up for mainly pizz/jazz. I keep another bass dedicated to classical playing. The arco bass is a better made instrument and came well set-up. Intonation and even tone across all regions of the board are easy with this bass. But the one which needs some work has a variety of problems in this are, and gives some trouble with intonation, evenness of tone, and general playability. (On the other hand, it has a sound to die for, and window-rattling power even though it could also use a soundpost/bridge tuneup.)

    I will post back here with a followup once all is done in case anyone finds my experience helpful, though it might be another month or two.
  5. Maybe this needs it's own thread, but I was wondering... does anyone have any kind of drawings, diagrams, pictures etc. of what sort of shape a good fingerboard *should* have? I'm thinking mostly of the scoop or relief of the board, but the side to side shape (radius?) would be interesting too. I'm going to be getting mine reshaped soon, and I'd like to get an idea what to ask for and talk about (other than how it plays, obviously) before I start talking to people about getting it done.
  6. In the world of violins, for all practical purposes the size, shape, internal and external dimensions were standardized by Stradivarius some 300 years ago. In the doublebass world, this has not happened and the instrument continues to evolve with a vast assortment of size and shapes. Fingerboards continue to evolve. We have two major types, the round and the beveled fingerboard. While the geometry of the round board is simpler than that of the beveled, it is far more complicated than a simple single radius such as found of guitars. It's quite common to see a round FB with a different radius at the nut than at the bridge end. The geometry of the beveled board is considerably more complicated. It's not just taking a round board and planing off the flat area. The actual center of the radius has to be moved. Then we throw in the variable width of the bass table (top). If the FB radius (and in turn the bridge radius) is too small for a given instrument, you have the possibility of hitting the top with either the tip or bowscrew button. If the radius is too large, bowing the individual strings becomes difficult. If you play primarily pizz, you probably will prefer a flatter arch. What all this comes down to is that there is no stardard that fits all basses. Trying to change the radius of a FB that is glued on the instrument is not a simple task. Replacing the FB is sometimes the only satisfactory way to achieve this goal. The bass luthier weighs a lot of factors when deciding how much dip or scoop should be present. The type of strings dictates different amounts of dip over the length of the FB. The ideal is start with an absolutely flat (end to end)surface and then remove small amounts of wood outwardly from the center of the length until you reach the point where there is no buzzing of the strings against the FB when you play. Too much dip only makes the instrument harder to play. How much is enough? I've been doing this kind of work for 40+ years and there is still a lot of trial and error in the process. Any bozo can plane a fingerboard, but it takes an experienced bass luthier to do it so that your bass plays as easy as possible. Tell your luthier what the playing problem is with your fingerboard and let him use his past experience to do the job for you rather than asking him to redesign the fingerboard.
  7. Thanks for the reply Bob. I was allready aware of most of what you said. I'm not really looking for any standardised shapes or measurements, I was just thinking that maybe there were some pictures or diagrams floating around that simply detailed some aspects of what generally makes a good fingerboard so that I could get an idea of what the luthier is dealing with and trying to achive. Like say, some pictures of a good fingerboard with a straightedge, showing the basic shape of it. Only part of my interest comes from needing work done on my own instrument; I also hope to learn to repair and make instruments some day. So anyway, if anything like that exists I'd be interested. Also any books or particulaly articals on the web about bass setup that are good. (I appologize for hijacking this thread, too...) :p
  8. If you find one let me know. I've never seen one.
  9. Damon Rondeau

    Damon Rondeau Journeyman Clam Artist Supporting Member

    Nov 19, 2002
    Winnipeg, baby
    I've done a lot of web research on this, and I'm with Bob. It's not there.

    In fact, I'd have to say that Bob's rundown on the fingerboard is as fine a description of the factors involved as I've read.

    Being able to set up a fingerboard is one of the big MOJOS that real bass luthiers have in their possession. Let them do their bad thing...
  10. hmmm. Allright then, I'll just see what I can find. :) If anybody's interested, when I get my board done I'll take some before and after pics just to document one case of the difference between a sucky and a (hopefully) rockin' setup.
  11. Actually, I found some info about fingerboard planing, albeit quite technical, with charts and graphs. If you can get between the math, I think it's the best I've seen. Most luthiers will probably look at this and go "Huh?", but like I say, if you can ignore the math, it can draw a pretty good picture of how a fingerboard should be (open to interpretation, of course). If you are good at math (and geometry, I guess) then you're way ahead of me. :)
    Here's the URL: http://www.nrinstruments.demon.co.uk/InstMain.html
    You will need to go about 2/3 of the way down the page to "Curving a Fingerboard to Improve the Action".
  12. Damon Rondeau

    Damon Rondeau Journeyman Clam Artist Supporting Member

    Nov 19, 2002
    Winnipeg, baby
    Curious. I've seen that before, but I'm pretty sure it was without the math stuff.

    I hope this doesn't sound bad, because I'm a math and graphs geek my own self, but there's a world of difference between comprehending the fingerboard mathematically and being able to confidently plane ebony to a fine, musician-pleasing tolerance.

    Just learning how to keep the steel sharp will keep ya busy for a few years....
  13. I remember first reading about the logarithmic spiral fingerboard maybe 25-30 years ago. I actually tried it on one fingerboard. About all I can remember about it now was that it took an unbelievable amount of time to do it and the end result was something that certainly wasn't worth all that time.
  14. The 'arcus ellipticus' fingerboard was patented by Allan Van de Bogart back in the 1960's. He branded the endgrain of neck blocks with that name, and is own, Latinised as 'Allenus Van de Bogarticus' inside a double-lined rectangular frame (very large and nicely made electric brand, it seemed) before gluing on these fine-grained and carefully wrought, and very heavy fingerboards. The underside of the board went in a curve as well, departing from the flat gluing plane to reach about 1/2 depth or a little more at the end. I know nothing else, except that he was (perhaps still is) a 'cellist here, and that only one local player still has her fingerboard intact. She uses it little, being mostly a piano instructor, but when she played on it in the VSO she liked it well enough. The bass was made in Seattle, and was the only one ever made by a now-gone luthier, some Italianate name... I forget, but it was a lovely bass. Interesting innovations too, in endpin construction and tuner design. It's been years since she needed work, as it just sits now. Last time she came was in her last year with the Philharmonic, needing a seam mended. Didn't drive all her life (something we share), so she came by bus about 10 miles in -9°C, with extremely low humidity. Ill-advised, but I hadn't expected the visit. No cracks though.

    Anyway, the fingerboard of which you were thinking may have been by this gentleman, Allen, who I believe was from the Boston area by his accent, or perhaps further towards New York. He has (or had, as last time I saw him was as a stand partner during a season with a local string orchestra, over 10 years ago, and he was very old then) an incredibly deep and authoritative voice, one of those 'voice of God' sorts that makes a room full of heads swivel when he asks if there is any cream for his coffee, or which way the the washroom. A rock-solid handshake too. I can easily imagine his younger days, with no one resisting the least bit his statements regarding the mathematical superiority of an elliptical fingerboard of precise dimensioning. And who knows, maybe he was correct! Nicely carved, anyway. Lovely rounding of all four edges, the way I like to make them so that a player doing a lot of pizz work doesn't get bothered by the sharpness of anything. I go on about it because overall it was refreshing to see this unusual coalescence of fine workmanship, in the hands of a player of extreme sensitivity. Sadly, I discovered on that visit that some 'theorist' had removed the lovely spruce under each bridge foot to some unknown depth, and inserted patches very neatly of a much finer-grained Douglas fir. Otherwise, the bass had not a mark upon it, after more than 25 years out in the world. These patches fitted very exactly, and I'd have thought them the maker's except that they didn't seem to go with the generally classical style, nor were they varnished in the same colour of pale gold. More like varathane. So it goes. Always a fly in the ointment. Still, a lovely sounding bass.
  15. Jeff Bollbach

    Jeff Bollbach Jeff Bollbach Luthier, Inc.

    Dec 12, 2001
    freeport, ny
    I am just not getting a picture in my head of this doohickey. It is not straight under the string? What is different about the board? Obviously I have never seen one. Maybe thats a good thing.