Various questions from a beginner luthier

YehonatanV

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Hi all, first timer here!

I am now beginning my first LP build (with the help of an expert luthier, unlike myself), with the intent of making some changes to fit my own tastes and preferences.
I have a few thoughts and questions and was hoping to get your educated opinions. Perhaps these questions are different enough to warrant separate threads, but for now I'll just summarize them here.

1. I'd like to do a satin finish on the neck. I thought about using a combination of Birchwood Casey products: Sealer & Filler -> Tru Oil -> Wax. I really love the feel on my Music Man Silhuoette and aiming for a similar feel. So:
a) Do you think this should work well on a mahogany neck (hence the prior pore filler)?
b) Would it be better to first finish the body and neck separately and then glue them together, which means only masking off the mortise and tenon, compared to first glue, then mask off and finish each part when they are already attached? (Or some other alternative?)

2. I'm considering going for a compound radius. I haven't yet decided on the exact details, but let's say it should extrapolate to something like 16" at the bridge. If I use, e.g., a bell brass nickel plated bridge by ABM, I would need to notch the middle strings slightly more than the outer ones to deviate from the built-in 12" radius of the bridge. Would that be too much and ruin the nickel plating?

3. I am planning on using Allied Lutherie's FlexStrong truss rod with a spoke wheel, for which I will dig a small cavity at the edge of the fretboard (the "23rd" tab).
a) Can it create any problems being so close to the neck pickup? It's supposed to be 100% stainless steel, but I'll check with them if it contains stuff that'll make it paramagnetic. Anything else to worry about?
b) Given that it doesn't need to protrude from the headstock like the regular one does, what would be the appropriate length? Do I need a full ~17-18" long rod, or can I use their 14.25" offering, or anything in between?

Finally, a bonus question :)
Feel free to skip!

Watching Freddy Gabrsek's wonderful LP tutorial series, there was one video where he demonstrates how slotting the freboard completely changes its tap tone response. Together with the eternal debate on the tonal impact of the fingerboard, I was lead to the following thought:
First, let us approximate the fretboard as a series of transfer matrices. The source of vibration passes through the fretboard (and neck, but let's put it aside for now) until it hits the closest fret tang. The change in material properties induces both reflections, transmissions and dissipation in a frequency dependent manner. From the fret tang, the sound wave goes back to wood, back to tang etc. This makes it clear why higher frequencies are damped compared to lower frequencies, and gives a rough qualitative explanation to why the resonant frequency of the slotted fretboard decreases significantly. I suppose one can easily refine this rough model, but just the basic picture here...
With that in mind, what would happen if instead of pressing frets, we were to just glue them to the fretboard, without any trang? I guess some minimal tang would be required to stabilize them, but it seems to me that standard tang is unnecessarily long, as most of the force acting on frets is perp. to the board, and there is almost no torque (only from the slight breaking angle due to tightly pressing the string to the fret when playing).
So there are two aspects here: one is the mechanical consideration for tang height and stability, and the other is what would happen tone-wise to a guitar with strictly minimal tang? That could possibly allow high frequencies to propagate more freely. I have no predictions on how audible this change would be, but at least in principle I think it's an interesting experiment. I'd be happy to hear your thoughts/experience.

Cheers,
Yehonatan
 

cmjohnson

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You're going way too theoretical for guitar work. The resonant alterations that might occur between pressed vs. glued and pressed in frets is utterly trivial and insignificant. Totally ignore it. Everybody else does! Use standard types of fret wire, and hammer or press them in and apply a little glue if you want to. But you DO need a substantial tang on the frets, because the frets need to be stable in the neck.

I've refretted a guitar that had been refretted so many times in the past that you could pull the frets out with youir fingernails. On that guitar, I replaced the fingerboard. It was necessary.

As for a compound radius, just keep in mind that the nut end of the board and the bridge represent the two end points of the theoretical truncated cone that is your full playing surface. The ratio of the smaller end and larger end radiuses should exactly match the rate of the increase in width of the string path from nut to bridge. (If the radius changes by 25 percent, then the bridge string width from high to low should be 25 percent wider than at the nut.) This creates a fretboard that is slightly thicker in the middle as it goes toward the body, while the edges of the fingerboard will remain absolutely even in thickness over its entire length.
 

fatdaddypreacher

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i shoot lacquer exclusively on my builds, primarily because i find it easy to work with, love the way it polishes, is easy to work with, and i'm a dinosaur. I say that to say, i wouldn't see a need to change finishes on the neck, as you can take lacquer and fine sand it one all fill work has been done, thus knocking the gloss off of it. depending on the final grit of paper, you can obtain a smooth satin finish. i wouldn't know why you couldn't do that with other finishes as well. i generally leave mine polished, but have knocked a couple back with 2500 grit and it worked fine.
 

Roxy13

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I do have one suggestion for you unless you are totally set on that ABM bridge. Gotoh makes one that has a 16" radius to begin with.

Ok, actually it says it's 15.7" radius:

 

lowatter

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I suppose that if you're concerned about the tap tone being compromised by the frets/tangs etc, have you considered fretless? I have no experience or further input on this matter but it just came to mind. Maybe a true "luthier" can chime in on this. There's a great source of help here on this corner of MLP if you're willing to listen and learn.
Re-inventing the wheel or taking roads less traveled can be a long haul.
 
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LtDave32

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First, much welcome to the forum. We're glad you're asking questions and we welcome all of them .

But I have to ask; If you have an "expert Luthier' helping you out, does he not have these answers to your questions?

Of course, we'd all be very happy to answer them, I'm just a bit curious as to what your guy says..

ps, on a first build I wouldn't recommend a compound radius. that can be a bit tricky to get right. I'd stay with simple.
 

fatdaddypreacher

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i thought the same thing about asking his luthier, and also feel the way you do about welcoming questions....goodness only knows how many questions i have asked.
 

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