Glass Fretboard - installation and intonation questions

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?)

 

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.

 

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.)

 

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.

 

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?

 

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?)