Glass Fretboard - installation and intonation questions

Discussion in 'Luthier's Corner' started by jar_fretless, Nov 11, 2016.

  1. jar_fretless


    Oct 24, 2016
    I have been considering epoxying my fretless fingerboard (see topic: “Fretless Fretboard: removing toe-in”) but am concerned about intonation and am now considering a glass fret(less)board now. (I’m doing this to a guitar. Since more basses than guitars are fretless I’ve gravitated to this bass forum—and am so far very impressed.)

    Why glass?
    - Glass is perfectly flat and hard (my limited experience with epoxy is that it is not as hard). It can be, but should not need to be polished.
    - Glass can be worked using sandpaper. (I may need to concave/radius the bottom to make up for slight neck relief [fine for a fretted instrument] and I might need to slightly radius the top.)

    Neck Relief: Do I need to absolutely match the bottom of the glass to the existing fretboard/neck?

    The reason I was going to use epoxy was to remove the neck relief. I figured it would be the easiest (though luthiers on this forum have sworn off ever using epoxy again) way to deal with this. However I watched a YouTube showing 5 approaches to microtonal (acoustic) guitar where clip-on replacement fingerboards performed quite well—leaving me wondering how important it is to ensure absolute glass-to-wood contact with the existing fretboard and wondering if I could use other materials (possibly epoxy!) to ensure the glass was securely in place.

    Q1) It’s an electric guitar. I know the material makes a difference because of its hardness and flatness, but, aside from structural considerations, is amount of fingerboard material/neck contact going to make a big difference. (Another way to put this question is: If a thin but totally unbreakable slab of glass existed, could it be securely attached only at both ends and work well?)
  2. T_Bone_TL


    Jan 10, 2013
    SW VT
    No - short, thin, not totally unbreakable but pretty tough, hunks of glass exist - look at glass cell phone screen protectors. Presumably longer sections from which those are cut exist, as well as the somewhat thicker material of the screens themselves. Thin glass is flexible. The middle would be all wobbly if not supported. By the time a ~20" long hunk of glass is not very flexible, it's substantially thick. While some folks may have sworn off epoxy, it's a perfectly good solution to "fill and support" - though with a glass top over it, a silicone product might also work well.

    I continue to question (as I did in your prior thread) the value of making the unstrung, non-adjustable truss rod neck "perfectly flat" since it almost certainly won't be, with string tension once strung.
    Will_White likes this.
  3. Jazz Ad

    Jazz Ad Mi la ré sol

    I really wonder how one would attain proper neck relief with a glass fingerboard.
    I also see structural issues between the neck and the board. Wood and glass behave very differently and the joint will likely crack, unless you find THE ideal glue.
    monsterthompson likes this.
  4. jar_fretless


    Oct 24, 2016
    I asked about the hypothetical strong/thin glass because I wanted to know if the glass going on the neck needed (for intonation purposes) to make contact EVERYWHERE or if it just needed to be attached in a way that was structurally sound (pun unintended).

    Because you suggest the possibility of a silicone product between the fingerboard and the neck that says to me that it's OK to use a medium that's soft and secure. (That the relatively soft medium of silicone should not affect intonation because it is not the surface the string contacts.)

    It seems that the truss rod is doing it's thing (maintaining the disposition of the neck) quite well. It's just that it is not adjustable, therefore requiring that the player who originally bought the guitar be satisfied with a neck with slight relief.
    Last edited: Nov 11, 2016
  5. jar_fretless


    Oct 24, 2016
    The glass fingerboard, by virtue of the fact it's perfectly flat and straight, would attain proper neck relief provided it were positioned accurately.
    The aforementioned suggestion of using a silicone glue to take up the space between the glass and the neck's relief would keep it from cracking (wouldn't it?). (Unless, of course you really treated it harshly.)
  6. jar_fretless


    Oct 24, 2016
    By the way, I'm going to create a prototype of sorts before tackling the guitar.

    The fretboard of a mountain dulcimer is straight, short, and thin. It should take a piece of 3/16 plate glass fairly easily--I'll have to heighten the nuts--raising the strings--on both ends.

    - First I'll simply lay it down on the fretboard, frets and all (with maybe putty of some sort to hold it in place.
    - Then I'll create for the glass a small frame which I'll be able to clamp (using t-screws or screwed dowels) to the straight sides of the fretboard...
    - And if all goes well I'll consider a permanent way of gluing it to the fretboard.
  7. I think I can see what you're saying. It could work, but I don't see the advantage of using glass over epoxy, aluminium or even stainless steel. Secondly, glass is notorious difficult to work, otherwise lots of things would have the sort of glass coating you're suggesting. I guess you could try one, but I really think you're on fool's errand. I'm not saying don't do it, but I am saying, be prepared for lots of breakages and heartache.
    edwinhurwitz and smithcreek like this.
  8. Jazz Ad

    Jazz Ad Mi la ré sol

    I can't see how, since a well adjusted fingerboard is anything but flat. Strings vibrate in a curve that the neck must follow to get low action.
    I don't understand your goals. The points you quote as advantages to using glass are not.
    Silicon based glues are very soft and dampening, not what I'd consider ideal for a neck.
    Glass will get scratches from the strings over time and you won't be able to get rid of them, which would take 5 minutes on an epoxied neck.
    Adjusting neck relief is impossible with glass, yet you plan to use wood. It would work better with a very tight neck material, like graphite.
    This makes me curious but not very optimistic regarding your project.
  9. Beej


    Feb 10, 2007
    Vancouver Island
    I think your concepts are good, but with all due respect, it might be worth building a few fretless fingerboards to get your "normal" techniques down before taking on something that will be much more challenging and expensive from an engineering and design perspective... :)
    RyanJD and Will_White like this.
  10. michaelwayneharwood

    michaelwayneharwood Builder of the Wastelands Commercial User

    May 1, 2014
    Owner Melodious Resonance Constructs
    Here's an instructable that may assist as it covers the basics of laying glass down on top of an existing fingerboard on an acoustic guitar: How to make a fretless guitar with a glass fretboard!

    Personally I think this is an awesome idea! Please keep up posted on your results!
    reverendrally and Jazz Ad like this.
  11. Jazz Ad

    Jazz Ad Mi la ré sol

    We at least know it can be done
    michaelwayneharwood likes this.
  12. Ross W. Lovell

    Ross W. Lovell

    Oct 31, 2015

    My only issue is how it will be attached? Glass will not like being epoxied to a piece of wood that moves, guessing either the glue will shear or the glass will break in some manner.
    tryinalearnDan likes this.
  13. Glass is really quite flexible in sheet form. I spent some time explosion testing gas fires and slow motion video footage showed the glass moving like a wobble board.
  14. michaelwayneharwood

    michaelwayneharwood Builder of the Wastelands Commercial User

    May 1, 2014
    Owner Melodious Resonance Constructs
    Ned Evett plays a glass fingerboarded guitar: | Ned Evett
  15. jar_fretless


    Oct 24, 2016
    There is one more thing I've been advised to do before going the glass or epoxy route (stainless steel??? I wouldn't even know how to approach this) and that is to:
    Securely position and clamp the neck to a stable surface in such way that I can apply heat to the neck while gently (using the clamps) bending the neck to get rid of the relief... (My local Luthier has a device designed to apply heat to a neck but said that I ought to be able to use a couple irons to achieve the same result.)

    Any of you acquainted with this method? Should I start with low heat or not go above a certain heat? Anything I should be careful with?
  16. DLemos


    Sep 7, 2015
    I wouldn't use glass on a wooden neck. A metal neck... maybe?
  17. CGremlin


    Nov 1, 2014
    Palm Bay, FL
    I can't really offer any solid advice on the pros/cons of a glass fretboard, but I will say this - if you're going to be sanding on it at all, keep it drenched with water or wear a good mask. You absolutely do not want any glass getting into your lungs.
    superheavyfunk likes this.
  18. superheavyfunk


    Mar 11, 2013
    I just wanted to reinforce this by quoting it. I've had some second hand experience with micro shards of glass in the lungs (and eyes) and it is probably the absolute worst thing that can happen to a person, after pancreatic cancer or something else equally horrible. Avoid it at all costs.
  19. jar_fretless


    Oct 24, 2016
    Your (glass powder related) cautions/advices are well worth a sincere thank you.

    Anyone heard of the heat/clamping approach to straightening the neck? (Is this worth starting a new thread?)
  20. Will_White


    Jul 1, 2011
    Salem, OR
    It works but it's a semi-temporary repair in that if you don't have a truss rod it will want to warp again.
    reverendrally likes this.