Author Topic: Scalloping the guitar fretboard - possibly also renovation of the instrument  (Read 2445 times)

Offline philf

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I watched an excellent TV programme on Crimson Guitars and Marshall Amps yesterday.

One of the guitars they were making had wriggly frets. I think they call them True Temperament.

Crimson do guitar making courses and have lots of YouTube How To videos.

No use to me as I'm totally inept when it comes to playing any instrument - but very interesting nonetheless.
Phil Fern
Location: Marple, Cheshire

Offline sorveltaja

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Yeah, I've seen those kinds of frets. I guess, that they are quite difficult to make, unless one has dedicated cnc-based machinery. On the other hand, I've also seen pictures of 'diy' tempered frets/fretboad, where the frets are cut in six pieces, which are then glued to the fretboard.

But in general, I think that only the ones, that have an absolute musical ear, would benefit/hear the difference, when compared to ordinary frets/fretboard. I can only imagine, of how stable the construction of the instrument should be in that case.

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Simplified linkage:



And machined one:



It's splitted half, so that it's probably easier to install/take out, without the need of removing strings from the retainer.

I tried couple things, considering the previously mentioned test using slide bearings, but nah, the eccentrics(in red) should then have a mirror finish in them. Too much hassle, so I'll wait for the 12x18x4 ball bearings to arrive instead.

Again, if all goes as expected, then some carving to make the linkages less blocky.



Offline sorveltaja

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Well, it's 'back to the drawing board' -time again, as there was one thing, that I had totally neglected - the spring.

When testing the eccentric rod, part of the spring seemed to always block it/be in the way. One way around it could be to use a 'fork' in the middle:



It's just a part of some kind of hinge, that has M8 thread. The fork is 3mm thick, which should be more than enough rigid for the purpose:



So, plan is to take 6mm axle, machine a flat surface for the sacrificial grub screws, that hold the eccentrics at the same angle, and then, silver solder them and the fork together.
After that, removing the part of the 6mm axle, that is between the fork. It should provide enough room around the spring, but we'll see.

New parts, that are waiting to be machined, with new ball bearings:



12mm steel axle, that I have for the eccentrics, is 0,03mm undersized, so the ball bearings have too much play, and therefore can cause rattling, and other noises.

There I was thinking:"how to expand the diameter of the surface, using simple tools, that I have?".

Answer might be to use a cheapo tube cutter:



I have used it in the past for brass and aluminum, and was surprised, that it can make grooves for the steel bar also.

When testing with ball bearings, yes, it seems to actually expand(displace?) tiny bit of the surface.

 

Offline sorveltaja

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"Forky thing" soldered, after some cleaning:



One ugly bugger, but if the concept works, then there is lot of room to improve the appearance(but it's not that important to me). I fitted the ball bearings by using previously mentioned tube cutter, to raise the surface, then fine diamond file to make a snug fit.

One thing, that I'm not so sure about yet, is that are the 12mm eccentrics enough to provide a decent range for the tremolo.

Next thing to do, anyways, is to make adjustable end pieces, that allow back and forth movement, to 'dial in' possible sweet spot(s) in eccentrics' rotation(and therefore the tremolo bar's positions).
Also to find out, if the eccentric rod's ends need something else than slide bearings, to allow as friction free action as possible. If so, I have already 5x9x9mm needle bearings for that. 


Offline sorveltaja

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Tremolo test:



It definitely needs ball/needle bearings for the ends of the eccentric rod. The tremolo range itself is rather mild, when compared to Fender or Floyd Rose -type ones. So, no dive bombing yet.

Obviously, the more eccentric the eccentric is, the wider the range. Although possible, I'm not sure, if it's practical to use much larger ones to increase it, as it's not easy to find slim enough ball bearings for bigger diameters(at least from local dealers).

One further option could be to make a 'crankshaft-connecting rod' -like linkages, allowing the use of a lot smaller ball bearings. I wouldn't mind possible steam punk -appearance, as long as it follows the "kiss"(keep it simple, sorveltaja) -principle.

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In general, the concept seems to work rather well. When pressing the tremolo bar(a spanner) down, and releasing it, the strings get back to tune. When moving it up and down, and releasing it, the strings get 'almost' back to tune. Just a bit of flat/sharp, depending of the direction.

Offline sorveltaja

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Today, while wondering how to make the tremolo more 'twangy', I browsed the online version of the '507 mechanical movements', and suddenly an idea popped out of thin air:



To increase the eccentricity, using already existing combination of parts, the blue ones will be added. The eccentricity should then go from 2.5mm to 8.5mm.

I'll use mild steel for them:



The axles and 'crank webs', after machined, are then silver soldered together. Before that, I should probably make the webs from aluminum, and use grub screws for both axles, to test, how close or far that 8.5mm is, when compared to 'traditional' floating tremolo like Floyd Rose.

Also the end pieces, housing the ball/needle bearings, need to be made of metal, as the printed ones are way too elastic.


 



Offline sorveltaja

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Frankenstein Tremolo has a new, temporary arm:



It's a Strat-style tremolo bar. I had to increase the eccentricity 2mm, as I don't have M4 grub screws, and the ordinary ones didn't fit so closely. So now it(eccentricity) is ~10.5mm.

When testing, and comparing the action to commercial tremolo, it's almost there, so it's close enough for me. Stability(or how the strings return in tune) is to be found out only after the construction is all-metal. The end parts(currently printed ones) might then have ball- or needle bearings, if necessary.

After all, I'm glad that the essence of the "flunkenstein tremolo" has finally started to show signs of usability. I'll do some finishing(filing/machining) only for the parts, that are protruding, or are in the way, like the aluminum ones, that form the linkages between string retainer and eccentrics. Also that M8 stud, in the middle of the 'fork' is to be shortened.

What's left, is to make the additional 'crankshafts' out of steel parts, that are then silver soldered together, to get rid of the lowermost pair of M4 screws. The M8 stump(once shortened), is better suited  for the Bigsby-like tremolo bar. If memory serves, I should have some very soft, 5mm aluminum sheet, which could be used to make that.

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Other things, after that tremolo is done:

- make the roller nut housing from alu/brass 
- remove as exact as possible amount of wood from the end of the fretboard, to get the rollers center in the 'zero fret' -position
- make new roller elements for the bridge, which follow the neck's 400mm radius(part of (possible) fine tuning process)

I could go on and on, but better to take one step at a time.


Offline sorveltaja

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New, soldered parts for the tremolo:



I used round 12mm mild steel bar for the webs, as there was a lot less material to be removed, when compared to 25mm one, that I originally intended to use. The lathe, that I have, has a whopping 60W of raw power, and it would take forever to machine such pieces from a bigger steel blank.

The bottom surfaces of the webs need some rounding, as they will end up being quite close to the surface of the guitar.

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In the meantime, I've been also looking ways to machine the roller nut housing out of metal. Only problem is, that it's a bit over 43mm wide, and would need a rather long 1.5mm drill bit to make the hole for the axle. At some point, I'll order couple of them, but for now, it'll have to wait.

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I guess, that now fiddling with the tremolo mechanism can take a rest, and it's time to concentrate on the tremolo arm. I found the previously mentioned 5mm aluminum sheet, so it will be used. The form of the (tremolo)bar isn't yet clear, but for a starters, something like this:



Cylindrical aluminum(or steel) part could hold ordinary M8 steel nut in it, as it doesn't wear out so easily, as alu does.

Offline sorveltaja

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Today some filing:



The shape is from Bigsby B11 -3d model. I had to scale it up quite a lot, so that it has a similar "reach", that Strat-style(although usually being closer to the bridge) one has:



As can be seen, the latter has slight upwards angled part in it, which allows more range, when pushing the bar all the way down. Otherwise the end of it would hit the guitar's surface, when doing something like 'divebombing'.

To 'compensate', using the straight bar, an angled part could be added to the end, where it connects to the tremolo itself. The angle of the Strat-style bar could then perhaps be a used as a 'reference', or as a starting point, when testing the action.

Offline sorveltaja

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The tremolo bar doesn't seem to need the angled part, as same can be achieved by moving the end parts(printed ones) closer to the bridge:



A bit of linkage shaping:



The upper half should preferably be even slimmer than that, so perhaps it needs to be made of brass or steel instead of aluminum.

Although the eccentric rod has ball bearings in it, pushing the tremolo bar down tends to drag the string retainer down also, and therefore limiting the range.
Don't know why that still happens.

Nevertheless, how about the analogy of an engine, that uses crankshaft, connecting rod, and a piston. Only thing, that keeps the piston movement linear, I guess, is the cylinder.

Fortunately the cylinder isn't needed in this case(but who knows). A metal plate, having suitable thickness, under the linkages, appears to do the trick.
Not a perfect solution, but it increases the range of the tremolo bar to much more usable level.

Besides, the bottom surfaces of the linkages need to slide along the metal plate only, when the bar is pressed down, so(hopefully) no constant contact is necessary.   

Offline sorveltaja

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Now the tremolo has aluminum end parts:



They have 6x12x4mm ball bearings in them, so the action is smoother. The weak points are the linkages, that just don't have enough grip on the string retainer end. I would rather make the linkages as long as possible, to lessen the retainer downward dragging, when the bar is pressed down.

But as usually on Strat-style bodies, this also has a curved bevel at the point, where the picking hand rests. Although the end parts are quite close to the bridge, the lowermost one(in the pic above) has already an increasing gap under it. 

I have a feeling, that it's time for some woodwork for a change. The body of the guitar is made of very lighweight wood, being easily butchered shaped, and then piece of wood added. Don't know yet, how to do that, as the resulting 'top' surface should be flat.

As always, there is only one way to find out.

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Tremolo bar itself could use a friction part, where it connects to the tremolo. Meaning, that it shouldn't wobble loosely, or be too tight to move(personal preference). That movement isn't associated with the string tension altering, but rather moving the bar out of the way, when one so desires.

One idea for that, could be to use a 'semi-locking' component, like on 'nyloc' nuts, that have a nylon component in them, preventing them from loosening.

The plan is to enlarge the bar's hole, and attach with small screws a piece of machined nylon bar, that has (partial)M8 thread to it:



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Again, another idea, considering the roller nut body, or housing, made of metal. The 1.5mm drill bits, that I have, are bit too short for drilling the 43mm deep hole in one go, so why not try to make some sort of fixture, that could possibly guide the drilling on both ends to make an acceptably straight hole for the axle.

Offline vtsteam

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Amazing the things you do, sorveltaja!  :bow:

I just ordered some silver braze today, myself. Some of the nickel-silver variety.
I love it when a Plan B comes together!
Steve
www.sredmond.com

Offline sorveltaja

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Steve, thanks. Don't know about amazing, but sometimes, when working on a project, at one point it starts to have its own "drive", and just by doing, things happen. Hard to explain, but it's like a continuous flow of some sort.

But yeah, silver soldering, or brazing is my favorite, as it doesn't require equipments, that use oxy/acetylene.

Aluminum brazing could have second place, although for some reason, it isn't as straightforward, as it doesn't seem to have the 'capillary' filling effect. On the other hand, I have used a propane torch, which provides enough heat to make solid, but not airtight bond between the parts.
It's been a while, since I used alu braze, and perhaps, if the tremolo bar needs to be extended(once it has been moved further away from the string retainer and bridge), it'll be used.

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Most of the curved part of the bevel removed:



I used saws like this:



Lowermost one is gyokucho, and other is, if memory serves, dozuki. I used the latter to start a straight groove, as it has a 'back bone'. Former one was then used to saw a slice off of the bevels surface.

Actually I had to make two cuts, to remove all of the curved surface. But anyways, those japanese saws, at least for me, are more comfortable to use, as the pulling, instead of pushing, naturally tends to keep the blade straight.

Then some sanding, to make the markings disappear:



Filling the holes:



Then filling the bevel with a chunk of pine:



Excess of the pine plank is sawed off, and it's time to make a milling fixture for further shaping:



6mm milling bit, and also a piece of 6mm metal rod, so it's a breeze to follow the contour of the body. After that, top surface is to be milled flat. But it'll have to wait overnight, to make sure, that the glue is dried, and the screws can be removed out of the way.


Offline sorveltaja

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Preliminary woodwork is done:



It's bit bumpy on the edge contour part, and will be taken care of at the stage, when the body is to be prepared for painting. At least there is now more room to move the tremolo away from the string retainer, as long as the fork of it doesn't interfere with the spring.

When thinking about the guitar bodies(and some furnitures), that I've painted in the past, they are far from good. Not that the looks is that important, but what can one expect, when painting with a brush, using thick paint.

For once, it would be nice to have a smooth, evenly painted surface.

Ordinary spray paint cans, available from hardware stores, have quite limited colour scale. The colour, or say, kind of colour, that I'm after, is subtly translucent, like when looking at tomato. It is neither plain red, nor plain orange. Closest acrylic colours are cinnabar or vermilion, but nah, they are still flat colours.

Anyways, small airbrush, although I have never used one, may be a considerable option. Good ones are pricey for occasional use, so why not make one. There are plenty of Youtube videos, where they use components/parts, that I already have. As long as it's simple, and doesn't spit, I'm in.

I have a small compressor, that doesn't have a tank, but few big, interconnected soda bottles can be used to beef up its 'breathing capacity'.
 
So, exploring the ways, of how to combine colours, and test the techniques, is a subject for a (possibly)forthcoming side-project of its own. 

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I managed to make almost straight hole, without breaking the 1.5mm drill bit:



First I drilled as deep as possible, and at the end, there was only 2 or 3mm of the drill bit length in the chuck. Very slow and tedious thing to do, as this kind of aluminum tends to stick to the flutes of the drill bit, and cause notorious 'snap'. Without having any proper cutting fluid, I applied some beeswax to the flutes often. Don't know how or why it works, but the thing that matters, is the end result.

The straight part of the hole itself is a bit loose for 1.5mm rod. When drilling from the other end, it went off by a small amount, as I expected. That eccentricity between the holes, after all, seems to be a good thing, as now that rod have to be tapped, or pressed to get it through, keeping it firmly in place.

Hard to say at this point, if that's the case, after the slots for rollers are machined. If the hole is still too loose after that, then other tricks like tinning the rod, will be used.

Offline sorveltaja

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Aluminum roller nut so far:



The slots are bit off, as I forgot to lock the lathe's carriage, when milling first three ones. It isn't necessarily the final nut, but for now, good enough. It needs to be shortened from both ends, and 1mm milled off of the bottom surface. Then some general rounding.

Offline sorveltaja

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Finally, the fixed tailpiece:



Other than that, not much progress today. When on a drawing board, I wondered how to make the new, longer linkages. If steel was used, it would be a very lengthy process, be it from solid, or discrete parts silver soldered together.

I have harder grade aluminum, than the already made ones were made of. It's just so much easier to form with a small mill, than steel. Brass sheet could be another option, but I wan't save it for the 'rainy day'.

Not sure yet, about how long they will be. It's again about the 'feeling' of the tremolo bar. When moving the tremolo further away from the string retainer, the bar hits it, or the bridge, when pressing it down, limiting the range. There is a fix: raise the bar, and see, how it goes.

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In the meantime, I have tested some diy-techniques from Youtube, considering finishing of the body. Most obvious is the crackling effect, using white glue and acrylic paint. But so far, the results are way too rough or exaggerated.

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Other than that, one idea is to laser print an image, or patterns to the black paper, then embed iron powder to them, by ironing. At first, there isn't much to see, but once the iron powder starts to react with the ambient air's moisture, it rusts.

I haven't tested that with black paper yet, but with white one, yes.

To get the patterns to absorb as much iron powder, as possible, the ironing process should probably be repeated.

I've done some tests using copper powder, but to get it more visible, it needs to be 'mangled'(don't know, if that's the right term), or maybe treated with an etchant, to 'open it up'.

 
 

Offline sorveltaja

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About the body finishing: it seems to be a bottomless rabbit hole, to test all the ideas, that comes to mind. Latest being about using procedures like electroforming(or electrotyping), to make metal patterns.

I think it's not the right time to dig in that deep into it. So, back to the 'kiss' -principle.

 

Offline sorveltaja

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New, longer linkages:



They are about twice as long as the previous ones. Infact, there was barely room in my lathe to bore the holes, so that's as long, as they'll get.

Action is smooth, although to stay in tune, it has use be used like a traditional Strat(and perhaps Bigsby) -style one.

The tremolo is more sensitive, than I expected, so that'll be the final mechanism(at least for now).

Next thing to do, is to shape the linkages. After that, if the ends, which hold the string retainer, are in the way, then move the whole system as far from the bridge, as possible(~10-20mm).

Then general rounding of the shapes of the bar. Its connecting point to the tremolo might need angled parts(printed ones in the above pic). Not sure about that yet.

When all that is done, it's time to move back to the neck. The nut needs to be centered to the 'zero fret' position, by removing wood from the end of the fretboard. I think I'll do some frequency measurements, while at it. To get any readings, obviously a pickup needs to be installed.





Offline sorveltaja

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Tremolo bar, after some filing and wet sanding. Linkages are preshaped, and ready for smoothing:





 



 

Offline sorveltaja

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When looking at it, there is http:// -prefix on my hosting server's address. I tried to access it by entering https, but for now, it doesn't seem to lead anywhere.

I'm generally using an older version of Firefox, as there are some plugins and options, that aren't compatible/don't exist in newer ones.
So, on the newer versions, maybe it's about 'site prefences', or security related browser settings.

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I think the idea for renovating this guitar has been brewing quite some time, as I found a preshaped pickguard for it:



Like on Strat-style guitars, the pickguard is used to hold the pickups, and also the volume- and tone control pots.

Only one small part of it has been snapped off, but it should be easy to fix.

It's made of clear 2mm plexiglass, and the plan is to bevel/smooth its edges, then lightly sand it to have a satin surface.

Offline sorveltaja

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Tremolo is now moved further away from the bridge:



Some work on the bar end:



It has a partially threaded nylon part inside the raising bush. Once the scews are shortened, then filing and sanding, to 'morph' the alu parts together.

As mentioned earlier, the linkages need to have some sort of 'liner', to keep the motion more linear. Some sort of roller/ball bearing based solution.

At this point I can see, how cleverly the Stetsbar tremolo(also mentioned earlier) is designed. Perhaps I'll try to approach that concept later.

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Again, another idea about finishing of the body. Maybe something, that contrasts its rather light weight. Something, that has a natural element in it. But we'll see.


Offline sorveltaja

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Test version of the rollers for the linkages:



Printed one:



It has a 3mm lapped steel rod(might be from cd/dvd recorder), and 3x6x2.5mm ball bearings(from computer supply fans). They have nice press fit tightness, but do they stay in place in use, remains to be seen.

Offline sorveltaja

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To put the tremolo aside, it's time to find out, how much the roller nut, in it's current position, causes deviation, when compared to 'correct frequencies'. Meaning, that the center of the rollers should ideally be at the zero-fret position.

So, before attempting to remove wood from the end of the fretboard, I'll measure the difference(s), just out of curiosity. I have another guitar, that has a locking nut, and it'll be used as well for comparison.

But yeah, for the measurements, at first, the pickup needs to be added:



It needs some kind of (possibly printed)supporting part under it, though.

Offline sorveltaja

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Pickup is now added:



As can be seen, the end of the fretboard is, where I tested dyeing. Well not exactly dye, but a felt tip pen. Then wiped with acetone to remove all the rest, that didn't absorb in to the wood.

I might have to remake the maple fret markers, as they'll get their share of black colour too.

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In the meantime I have also done some testings, considering the body finishing. I decided to stick with either copper-, or iron powder. The latter one seems to give more shades, from dark brown to blood red to yellow-ish.

Chemicals found in my closets: vinegar, citric acid, phosphoric acid, and copper sulfate appear to give the most visible effects. If there are results worth mentioning, I'll post some sample pics.

Otherwise, I'll just use some plain color for the finishing, and then move on with the project.