Author Topic: Scalloping the guitar fretboard - possibly also renovation of the instrument  (Read 936 times)

Offline sorveltaja

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I have an old electric guitar, that has been gathering dust for years, because of its condition. It was never in particularly good shape, even when I bought it decades ago.

On the other hand, it has a quite good neck(maple and rosewood), but uneven frets are what makes it not so pleasant to play. So it is a perfect candidate to practice fretwork techniques, like leveling and crowning.

But first comes the scalloping, even though I'm not sure what the outcome will be. Although there are lots of videos about it in the Youtube, I'm going to find my way to do it.

What is the fretboard scalloping anyways? Basically it's just removing wood from the fretboard. Ordinary one:



And same after scalloping:



What has kept me from doing it in the past, is that the depth of the wood removal needs to be somewhat shallow, and consistent through the whole fretboard. That way the neck's rigidity shouldn't be weakened too much.

Some testing, by filing about 1mm from the fretboard surface:



Different filing jigs were already tried, this being the latest:



It was printed, as machining that kind of piece would require enormous amount of work. Next to the file, there is a groove for the fret, that acts as a guide, so that the frets themself don't get filed.

On the opposite side is just a flat surface, that rubs over the fretboards surface, once the file doesn't 'bite' anymore. Different sizes/forms need to be printed, as the scalloping goes on.

Of course I could use Dremel to make the wood removal faster, but it would require way too complex jigs. Besides, I don't fancy having any kind of wood dust floating around in the air.

Next thing to do, is to use the above filing jig for rest of the fretboard.

 


Offline Lew_Merrick_PE

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At the most basic level, the position of a fret is the string length/17.835.  [In "pure harmonics," a distance of string length/18 raises the pitch one half-note.  The "17.865" value accounts for the incrrease in string tension created by fretting.]  Obviously you will have to account for the width of your fret wire in determining your "scallop" and reduce the "17.835" value to account for the added tension.  --  Lew

Offline sorveltaja

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Lew, thanks for the info. But the fretboard itself isn't part of the note-producing process, except on fretless instruments, like violin, contrabass, and such(in form of fingerboard).

In fact, on fretted instruments like guitar, the fretboard might not be necessary at all. Gittler guitar:



So the scalloped fretboard is one way to add a bit more freedom to the playing. It requires lighter touch, because it's easy to do unintentional 'microbends', just by pressing the string, as there is no wood close to the pressing finger, like on ordinary 'flat' fretboard. Also string bending is a lot easier, when the finger(s) don't rub against fretboard.

Project goes on. More filing:



Side markers are falling out, but I don't need them anyway.

Plan is to remove 0,5mm more by filing, and after that, plenty of sanding. It actually feels good to use some elbow grease, after previous electronics projects.

Offline Lew_Merrick_PE

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OK, if you take a "string" and tension it over two (separated) "edges" & "plug it," it will vibrate at a given frequency based on: tensioning force, shear modulus, and plucking duration.  Shorten the "separated edges" distance by 1/18'th and, maintaining the other "variables," pluck it with the same force & duration and the "note" played by the "string" will be on half-tone higher than the previous one.  However, when you "dish our between the frets you are changing the tension within the "string."  [My original Journeyman's rating is Luthier.]  --  Lew

Offline sorveltaja

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Yeah, there are plenty of things involved with strings, and frets.

Again, more filing. Arched scallops would look better. Instead the result is more like 'U-channels'. That is fine by me, as the filing fixtures seem to work well:



Bit of rounding on the areas near to the frets, which might not be necessary, but to get completely rid of that awful, glossy finish(lacquer/varnish perhaps), that the fretboard had in its previous life.

Fret markers needs to be redone, maybe using bigger, Fender-style dots. They have to be shallow, as there isn't much of wood left, and I don't like to hit the truss rod with a drill bit. But we'll see.

To go ahead of myself, if all goes well, I'm going to dye the fretboard as black as I can, and finally, apply several layers of matte lacquer to it.

Before that, after the scalloping is done, resulting fretwork dictates, if it's worth the effort.   






Offline WeldingRod

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I've got to ask; what is the benefit of scalloping?  Ive never seen it before...

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Offline Lew_Merrick_PE

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I've got to ask; what is the benefit of scalloping?  Ive never seen it before...
Scalloping makes it easier to barre.  --  Lew

Offline russ57

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I would think the tension and hence pitch would only change if you pressed the string right down to the scalloped fretboard - which would make it harder to play.
I presume the intent is to merely press the string hard enough to ensure the fret forms the 'edge' as Lew describes. Without touching the fretboard as normal.

I also have not heard of this. Interested in the outcome.



-russ


Offline sorveltaja

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As far as I know, there are very few big names, who use scalloped fretboards in their guitars. Most prominent, I guess, is Yngvie Malmsteen.

I remember reading somewhere, that he scalloped his early guitar(s) back in the eighties. Later on, his signature model Fender Stratocaster became available.

Other, that I'm not quite sure about, is Richie Blackmore. He also has scalloped signature Stratocaster model available. I have seen many live recordings of him playing, but never paid attention to the fretboard, as it's kind of hard to see, unless there are super close-ups.
--

Most of the rough filing is done, so it's time for rounding the areas around the frets a bit. At this point, some of the right sides of the frets are rounded, but barely visible in the picture:



Instead of using printed filing fixture, a lot more simpler solution was at hand:



The aluminum piece is attached to the file with double-sided carpet tape. Seems to work quite well, although one has to be very careful, to not to scratch the frets.

Obviously, the 'fret betweens' that get narrower, when going though the fretboad, need again another arrangement, but fret not. If it isn't easily achieved by filing, then slowly, by sanding.

Offline RotarySMP

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You are making a nice job. It will be interesting to hear your experience with the scalloped fretboard.

I have a Strat which was very heavily used by a previous owner, with long fingernails, which has some pretty deep divets in the fretboard. I considered doing something about them, but you don't even notice them when playing.
Mark
Best regards, Meilleures salutations, Mit freundlichen Gren, Cu salutari
Mark
https://www.youtube.com/c/RotarySMP

Offline sorveltaja

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Re: Scalloping the guitar fretboard - possibly also renovation of the instrument
« Reply #10 on: September 28, 2020, 07:56:42 PM »
Mark, thanks. While sanding the fretboard after filing, the finest grit was 240. As this is just an experiment, trying to remove all the file marks isn't that much needed. Maybe later, if necessary.

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Side marker holes were filled with rosewood dust and instant glue(cyanoacrylate). Then holes for the 6mm fret markers were made, by using printed jigs like this:



Fret markers are turned out of maple, as I already had some leftover bits at hand. They were glued with the same instant glue.

Instead of dyeing the fretboard black, as was mentioned earlier, perhaps the acetone treatment could do. Comparison:



I wouldn't use acetone for fretboards, that have any sort of plastic parts in them, though.

--
So, next comes the fun part: fretwork.
« Last Edit: September 29, 2020, 07:49:27 PM by sorveltaja »

Offline sorveltaja

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Re: Scalloping the guitar fretboard - possibly also renovation of the instrument
« Reply #11 on: September 29, 2020, 10:05:31 PM »
Today the guitar was prepared for the fretwork. To start hunting the buzzing frets, capo was attached to the first fret, as the saddle has a different radius, than the fretboard(actually, in this case, frets):



Then lowering the bridge, as low as needed, to bring out the string buzz on different frets. So far, it's not as bad, as I expected. I like super low action, so it's crucial to get them(frets) leveled anyway.

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First impressions of using the scalloped fretboard(no fretwork done yet): It definitely isn't everyone's cup of tea, but even at this early point, I like it.

Some pros and cons noticed(personal preference):

+ string bending fingers don't rub against the fretboard
+ makes the upper fretboard somehow more 'accessible', allowing easier, crazy bendings also

- might take some practice to get used to
- fingers could 'dig' deeper between the strings more easily, when compared to the ordinary fretboard

--
I'm going ahead of myself again, but I think the rest of the guitar is now worth of restoring, although the body seems like there were bunch of rats excavating:



 

 

Offline sorveltaja

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Re: Scalloping the guitar fretboard - possibly also renovation of the instrument
« Reply #12 on: September 30, 2020, 10:09:00 PM »
Not much progress today, as I had to do some arrangements to free enough table space. Also I've been looking for different techniques to do the fretwork.

In the project guitar, the string buzz seems to be concentrated mostly to high E string. Perhaps the first thing to try is a 'spot' -leveling, with the strings on.

Idea for that came from Stewmac video, where Dan Erlewine uses a diamond coated spot file. Particularly I liked the part, where he showed a very early version of it, that was just a wooden stick, with small piece of file glued to it.

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I have noticed after the scalloping, that the fret ends appear to stick out more, when playing through the fretboard, so they need to be rounded.

Another thing is, that one may not necessarily desire of having a full Yngvie Malmsteen -style scalloping, which I have done. Obviously there are a lot of other ways to make a partial, or 'milder' scalloping.     

An example of that could be the Richie Blackmore signature model, that has a 'progressive' scalloping.

Offline sorveltaja

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Spot leveling wasn't enough, so longer aluminum piece with 240 grit sandpaper was used to even out frets from 11 to 22:



String buzz is now gone, although, when the strings are set very low, even moderate pluck makes them buzz, no matter how much leveling is done. Simple cure for that is to raise them enough to suit one's playing style.

I'm surprised, of how different the guitar feels(in a good way) already. Next thing to do, is crowning of the sanded parts of the frets. Then rounding the ends of them.

And then, to the involved hardware.

Offline Lew_Merrick_PE

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Spot leveling wasn't enough, so longer aluminum piece with 240 grit sandpaper was used to even out frets from 11 to 22:
So have you ever seen a fret file?  --  Lew

Offline sorveltaja

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Lew, yes I have seen, but currently don't have one. Maybe at some point, as one diy-guitar, that I built in the past, needs awful lot of fret leveling(or even whole new fretboard).
More about that, perhaps, after the ongoing project is finished.

--
Frets are now crowned, and polished. For crowning, I used a triangle file, that has smoothed 'safe edges'. I have actual crowning file also, but it's way too coarse, leaving deep scratches.

But yeah, so far I've been having a good time, when making improvements to that guitar. Next thing is to find out, what kind of nut to use.

As the string posts of the tuning machines have some slack in them(need to take a look, if they could be modified, to make them firmer), I thought of putting a locking nut in, but nah, it would require fine tuners on the other end of the strings(like on Floyd Rose). Besides, it has too big footprint to fit:



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I'm not a fan of ordinary nuts, that have grooves in them for the strings. Other kind, that caught my attention, is a Fender roller nut.

To test the concept, I'll order some 3mm bearing balls.

Obviously one has to remove wood from the end of the fretboard, to align the ball's centers to the 'zero fret' -point. 



Offline sorveltaja

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What comes to the roller nut, today some drawing, based on photos of the original one, like this:



What I've found out so far, by looking at the Fender's installation manual, that there is a retainer cage to keep the balls from falling out, when changing the string(s).
Black/dark parts above the balls are rubber dampers, to mute the string vibrations between the nut and tuning machines.

Somewhat confusing is, that in the manual, the balls are called as ball bearings. The way I see it, the balls should act as linear bearings, moving back and forth, when the string tension varies(by string bending, or by using a whammy bar).

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Simplified version of the roller nut:



Ball pairs are aligned so, that the strings(in red) follow the fretboard's 400mm radius:



I have already printed the above model, but it'll have to wait, until the ordered 3mm bearing balls arrive.

--
Forthcoming ideas:

- to find out, what kind of mechanisms are used in the locking tuning machines, to convert ordinary ones, well - to locking tuners
- also to find out, what sort of tremolos there are, that are 'surface mounted', instead of 'through the body' -ones.
 

Offline WeldingRod

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It looks like the balls are fixed; just hard, smooth surfaces.  And cool looking ;-)

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Offline sorveltaja

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Yes, brilliant and simple concept. From what I've been reading on the net about users experiences, they are largely positive.

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When taking a closer look, of how the locking tuning machines work, they probably have their uses, but it's just a screw through the string post, to clamp the string. Similar 'locking' action could be achieved by winding the string so, that it 'locks' itself to prevent slipping.

--
In the meantime, also the flat mounted tremolos were looked at. One, that stands out from the crowd, is the Stetsbar tremolo. It's operating principle seems to be rather simple:



It appears to have linear ball bearings in it, as the bridge and string retainers move back an forth. Most critical part, though, is the spring tensioning system, that returns the bridge to its exact position, after the tremolo bar is used.

The way the springs work, isn't so obvious to me at this point, even when looking at the patent pictures. Reading the details in the patent text makes me yawn, as it's always formal, instead of being informative.

But after all, that's what leaves plenty of room for experimenting.


Offline sorveltaja

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First test version of the roller nut:



It uses 3mm bearing balls. To prevent them from falling out, while fiddling, I tried different offsets, to find the press-fit tightness. To get them out again, one has to destroy the nut, though.

I haven't removed wood from the end of the fretboard yet. To be absolutely sure, that the roller nut is worth it, first I'm going to make the tuning machine's posts as 'play-free', as I can.

After that follows abusive string bending session(s). Bridge has already rollers in it, so there shouldn't be too sticky points for the strings, but we'll see.




Offline sorveltaja

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The roller nut was tested, and results are not as good as I expected. Strings get still out of tune after bendings. Reason for that may well be the type of strings that I use: coated ones.
The specific breed, that I use, is Elixir Polyweb, as they seem to have most durable coating.

As the sweat from my fingers is like battery acid, uncoated strings are ruined in just few days.

This type of roller nut, with bearing balls, might work a lot better with metal-to-metal contact, as with uncoated strings.

But enough of that. I think that using real rollers instead of static bearing balls could be a better bet in this case, and therefore forthcoming subject for testing.

--
Ongoing, 'tongue in cheek' -test subject is this:



So, it's basically a part of a tremolo, thrown together from the parts, that were at hand. Exception is the spring, that had to be made.

At first, I tried the Strat-style tremolo springs, but even six of them together hadn't enough tension, to get the strings tuned for a standard tuning.

Next I looked for online spring tension calculator, only to find out, that it produces plenty of values of different variables, that I have no idea about.

Numbers aside, it was again time for parking the ball in the dark.

Strat-style springs, that I have, are made of 1.4mm spring wire. To have a single spring to take care of the combined strings tension, it needed to be stout, so 3mm wire/round bar was used.

Surprisingly, with the spring on above pic, the 'sweet spot' is a lot closer. In practice, when tuning the strings, they don't go higher than G(when using 'A' tuning fork).

As it's intentionally a 'floating' system, perhaps adding an adjustment screw to pull the springs' opposite end away from the bridge to 'compensate'.

In the end, if nothing else, this is an attempt to find the pitfalls, that many of the tremolo designers must have stumbled upon.

Offline sorveltaja

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Now the (possible)tremolo design has the end adjustment, allowing it to be tuned to the standard tuning:



Next thing is to find out, how to attach a tremolo bar, that moves the string retainer back and forth. If it goes well, then the lumpy one is replaced with something like this:



Round 12mm brass bar will be used for that. Bit of machining for a change.

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Even at this early point, that floating string retainer has already a Floyd Rose-ish(or other floating system) feel in it, which makes the string bendings/vibratos very easy. For me, at least, that alone is a jolly good thing.

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What comes to binding, when bending the strings(especially non-wound ones(G-B-E)), it is definitely located at this roller nut. When the string goes out of tune(flat) after bending, pushing down the portion of string, that is between the nut and tuning machines, brings it back to tune.



Offline sorveltaja

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Strings have now a new retainer:



When thinking of what kind of tremolo bar mechanism could be used, probably some sort of linkage is needed anyways. To make one, that fits under the spring and retainer, it would require a whole lot of machining.

Easier way, I guess, would be to silver solder some steel/brass bits and pieces together.

--
Before entering the tremolo stuff, the nut needed to be sorted out:



It's using brass rollers with printed body. At first, the strings got out of tune, when bending, but finally, after plenty of string stretching/retuning, it got better.

The way the strings are currently wound around the tuning machines' posts, isn't best possible, as they get tuned and loosened dozens of times, while testing.



   

Offline sorveltaja

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While waiting for the ordered silver solder to arrive, some fiddling with different tremolo ideas, bits and pieces:



So, using two hinges ganged together, to provide even pressure to the string retainer, could be an option. As it is in the above pictures, it doesn't work that well, as the hinges tend to press the retainer down, and detuning the strings, when the tremolo bar is released. 

Inserting a suitable thickness metal piece between the retainer and hinges makes it a bit better, without the need of retuning the strings after pressing down the tremolo bar.

Even better way would be to attach something like 'connecting rod', that converts the hinges' rotary motion to linear one.

Currently the tremolo is 'one way' only, decreasing the tension of the strings. When proper linkage mechanism is added, it should be possible to make it to act both directions.

Adding the tremolo is also an attempt to test the spring, that I made. There is nothing special about it; I used a mini butane torch to heat the 3mm wire, when winding it around the 8mm axle.
No further heat treatment. I'm not quite sure about the material, but it's harder than mild steel, maybe closer to piano wire.

I'm surprised, that it works as a spring, having enough tension to keep the strings in tune. After all, sometimes the guesstimating seems to work.


Offline sorveltaja

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Today some silver soldering:



So, the second test version of the tremolo uses two 12mm eccentrics to move the string retainer. 

First test setup, again, using bits and pieces at hand:



I have only one 12mm ball bearing, but when pushing the wrench, there is rather smooth movement, although the ends of the eccentric rod doesn't have too much of bearings yet.
Needless to say, perhaps, that there should be a pair of bearings, to get all the strings 'tremoloed' at the same time.

The above ball bearing is a bit too big for the purpose, as it has 28mm outer diameter.

To add linkages, or "connecting rods" between ball bearings and string retainer, this is, what I have in mind:



Green parts are 12x18x4 ball bearings, that I ordered. In the mean time, I might do some simulations with similar size slide bearings.