Putting relief in the frets, not the board?

[Jeremy Borkat]

Happy 4th, all. As a celebration of America's independence, I come here posting a quandary and looking for all input and thoughts. About 2 weeks ago, I read through almost every post here, and when my current dilemma came up, I figured this would be a better time than any to sign up. I work for a guitar company that makes very different guitars, and therefore has to do it's own unique style of luthiery, thus lending itself to occasionally unconventional solutions. This is my first time posting, so please excuse my limited knowledge of the jargon. I welcome corrections. Also, this may be wordy, but I'd rather err on the side of detailed caution.

Right now, I have a nylon string guitar, and the fretboard has no relief. In fact, when I put a straight edge on the top of the frets, the first 9 are dead level with each other, and from there, a fall-away develops and peaks to around 1/8-5/16inch gap between the bottom of the straightedge and the 19th fret. The reason for this is a process problem where a lot more material was taken off near the bridge side of the fretboard, leaving it a lot thinner up in the higher frets.

Normally, the way I would assume any luthier would go about it would be to remove the frets and flatten the board, however, the board in this case is made of phenolic, something which requires being sanded with more aggressive tactics than wood, sanded through 800 grit and requiring a good buffed shine in the end, something very difficult to do well while the board is on the guitar. Also, wood planes don't exactly take to phenolic very well (at all...) so a good leveling would require some hefty, time consuming elbow grease and a long radiused block.

As a lowly luthier in this small company, I usually have to do what I am told. In this case, I put up a hell of a fight because I was being told that "Classical guitar makers add relief in the fretwork all the time, and anything you do to this guitar will make it better. Just do a fret level and put more emphasis on the area where the peak of it is." My response was "There is so much fall away, fretwork won't do a thing, and I am sure classical guitar builders make sure their board is flat before they attach it to the guitar."

I've attached a solidworks sketch which attempts to visually explain it.

We are using Medium fretwire, and if I actually took the time to level the frets, the 9th-14th frets would disappear seeing as an 1/8th inch fallaway in the fret board would require some serious metalwork, leaving untouched 1st and 19th frets, and the middle of the board flattened, creating one of the most peculiar looking, unplayable boards ever.

Personally, I'd rather not touch the thing. I'd rather make a new fretboard than try what seems to be the "lipstick on a pig" method -- improving something which is really bad by doing minute adjustments will only improve it quantitatively in measurements and numbers, but not to anything but a precision straightedge. If anything, the experimentation will cause more issues. If it's not going to actually solve a problem, why spend so much time working on it?

So, fret folks, what should I do?
And hypothetically speaking, say I had a fretboard which was flat on a nylon string guitar, and wanted to add relief, could it be done to the frets in a predictable, repeatable way? My hesitations there are that filing and shaving frets progressively and putting more effort in one area than another will possibly yield unpredictable results, and I'd rather learn and get good at a process that's repeatable than having to play a guess/check/pray game with abrasives every time.

[Bob Webster]

Stick to your guns. You have the situation read right. It does need a new fretboard. Getting the relief, however, is another story.

Medium frets are just over 1mm tall starting out. Effective relief, say at the 5th to 7th frets, amounts to between 0.015-0.020", or upwards of 0.5mm. You can do this effectively by sanding and then profiling, but I think you've already figured out what the job will end up looking like. Further, later fret dressings would not necessarily be possible.

The best and surest way of getting the relief is to create it prior to fretting the fingerboard. My commisurations regarding the phenolic because just about your only option is to sand it.

Best of luck with the management.

Bob

[Tim Mace]

Go to Cumpiano's website and read some of his notes. ....if that's a reasonably accurate rendering is it too much of a butcher job to add a shim beneath to raise the end of the fretboard? I guess it's welded to the top?