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String Break Angle At Headstock...


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All of my builds, bass and guitar have used a 15 degree headstock angle, scarfed joint. (Actually, I have to check that number from my notes, but I believe that's it off the top of my head.)

I think I derived that number from whatever guitar I was cribbing notes from during my first build. I don't even know. It's worked well on all my guitar builds since then, as I've used a similar tuner layout and headstock style on the handfull I've built.

The first bass I did, it worked well, on the second, I had some problems with buzzing on the low E string, which where resolved by making sure I left enough string to get a few more wraps around the post and increase the break angle.

Anyway, to avoid this in the future, I'm wonder what sort of angle I should be looking for on the string as it breaks over the back of the nut - this would help me calculate things during the planning stages of the build, but I'm not quite sure what I should be shooting for.

EDIT:

On further inspection, perhaps the buzzing was the string rattling in the nut slot, (it was a 1/4" wide nut) as it was cut at a slightly too-steep angle, and the string only rested firmly on the nut slot at the fretboard side? So maybe my problem in the above example is something else entirely.

Regardless - I don't think the break angle of the string over at the headstock end isn't something I shouldn't pay attention to, I'm just not finding any info. I assume it's a range of numbers perhaps quite wide, but what to other folks shoot for?

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15 degrees is a very common angle for guitar and bass construction. I've never noticed any basses having a noticably steeper angle, so I think the nut was the culprit.

I'd suggest replacing the nut with a blank one, and carving fresh string grooves into it. And don't forget pencil graphite in there. Lets the string shift in the nut freely without binding. It helped on a buzzy bass of mine.

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Ah - the issue was not fret buzz - it only occured on the open string, and was resolved by gently muting behind the nut with a piece of foam - or even just gentle pressure from a finger on the string behind the nut. It was resolved more gracefully by increasing the break angle over the nut by ensuring that the string was wound further down the post. This of course points first to the nut; and next time I have the strings off this bass, I'll examine it, and make the needed adjustments or replacements.

I certainly don't need an inordinate amount of windings to resolve the issue, simply more than I usually use, and perhaps re-working the nut so the strings sit against the entire surface of the bottom of the string channel in the nut will resolve this issue in a better fashion (in looking at the instrument, I realize that they the bottom of the channel was almost a 16th inch lower than the bottom of the string - I usually cut my nut slots deeper than needed as I use a zero fret - on my guitar, the string doesn't actually touch the bottom of the nut slot like this bass, just the sides.)

But it makes me wonder about what role the angle of the strings over the nut plays- while the headstock was scarf jointed at a 15 degree angle, the headplate was rather thick, and the headstock thus thinned from the back (moving the upper surface of the headstock closer to the height of the fretboard) this in combination with the placement of the tuners (and what seem like rather high tuner posts) makes for a rather smaller angle for the actual strings over the nut than the 15 degree angle of the headstock compared to the plane of the neck.

And in my current build, I'd like to try lapping the headplate and veneers beneath it over the top of the fretboard behind the nut and zero fret. Something I've seen in one of Scott French's builds and one of Garehans) Since this moves the height of the headstock's face plane further up, it also moves the string holes in the tuners further up in relation to the plane of the fretboard, it further reduces the angle of the strings over the nut. Moving the tuners back from the nut should help some, I suppose.

So my current issues, in combination with thoughts about trying some different head-stock styles in the future makes me wonder what role this angle over the nut plays, even if it doesn't play a role in buzzing, and what sort of angle I should be shooting for in my future plans. I guess that was my primary line of questioning, regardless of the issues inherit in my previous build, and I once again let my long-winded-ness obscure my point, (He says as he finishes up another five-paragraph post...) by bringing up the previous build rather than focusing on what my main intent was.

So anyway - thanks for the help, guys, (seriously!) but anyone got any ideas on my main query - what sort of angle for the strings coming off the nut should I be shooting for? Whether it's a tilted headstock or fender style, or whatever, and regardless of whatever issues my previous build may or may not have.

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Think of how your strings behave, when they aren't open notes. It only gets the same amount of perpendicular force, or downward force, as your finger provides. You really shouldn't need any more pressure against the nut than your fretting finger would normally apply when playing further up the neck.

Consider how a zero fret works. There's a fret at the open-string position, and the nut behind the zero fret only acts to keep the string's lateral spacing. That means, at that zero fret, it doesn't really need any more downard pressure than anywhere else on the fretboard.

If you're serious about this, you could do the calculations to figure out exactly what angle the string would need to cut over the nut. It's a simple static physics problem. First, figure out exactly how much pressure, or force, you apply with your fingers when fretting. A scale or a load cell would give you this data (I know, I'm cheating, I've got load cells and scales all around me here at my work! HAH!). Then, do the equation in reverse. You'll have the pressure force, then you need to do a strut or bending moment calculation using that target force. You'll be looking to find the bending angle that provides the equivalent force, which will turn into a basic trigonometry equation.

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Fair enough. I hadn't thought about that. More math than I was hoping to do however, but should be an interesting thing to look at.

I'm not as up on this type of physics/math as I'd like to be - would I be correct assuming the tension of the string relates to how much perpendicular force is needed to be applied? This would go towards explaining why an angle that suits one string gauge or type of instrument may not be suitable for another - although perhaps I'm just grasping at straws.

I also wonder why I get a sympathetic ringing of the strings past the bridge on my jaguar-trem equipped guitar, (not audible through the amp unless at high gains) although the angle over the bridge is greater than the angle over the nut in guitars - I assume this in part is a different aspect at play, but I wonder if the force exerted at that angle would effect this.

And it veers into the realm of mojo, but are there tonal reasons for differences in angle?

I'm really overthinking this - I ought to just go make some measurements of the angle over the nut on a variety of known-functional designs from store bought guitars, take that into consideration when designing a headstock and make sure that nothing about by placement causes a radical difference in these angles. Removal of string trees on Fender-style instruments ought to give me an idea of what to look at avoiding.

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But it makes me wonder about what role the angle of the strings over the nut plays- while the headstock was scarf jointed at a 15 degree angle, the headplate was rather thick, and the headstock thus thinned from the back (moving the upper surface of the headstock closer to the height of the fretboard) this in combination with the placement of the tuners (and what seem like rather high tuner posts) makes for a rather smaller angle for the actual strings over the nut than the 15 degree angle of the headstock compared to the plane of the neck.

This is a good observation. The angle of a headstock is not the only factor in deterning actual string break over a nut. A neck with no heastock angle, can certainly have break angle. It just depends on the distance of the tuner post from the nut and the height of that post. This is what you should look at.

A good point is made about down force required to cleanly produce a not. Very little is actually required. The downward pressure also plays another role though at the nut and bridge as you actually will be setting the instrument in motion to a degree. Too little pressure and your strings may not have a very good coupling with these components. There is no firm angle that is best for all situations. Maybe a good point of reference would be an acoustic bridge. A 15 degree angle developed behind the saddle provides a good coupling, much more helps little. An acoustic bridge is going to have a lot more movement than an electric, and your needs would certainly not exceed that requirement(likely less is going to perform just fine). How much less will vary from instrument to instrument.

Rich

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...would I be correct assuming the tension of the string relates to how much perpendicular force is needed to be applied?

No. The tension of the string only dictates the pitch of the note.

For X thickness of string, it needs Y amount of tension, to produce Z frequency. Perpendicular force acting radial to the string does create a slight, ever so slight, amount of additional tension in the string. Why? Because the act of pushing the string down against the frets does, however so very microscopically measured, lengthen the string, creating more tension, raising the pitch. Ever fret a note just behind the fret, then fret it in the dead center between two frets and push the string all the way down to the fretboard? What happens? Pitch stretches and bends up. Same as with vibrato, if you bend the string by sliding it across the frets, it adds tension to the string and raises the pitch.

But you must understand, the distance between the string and the fret (also called action) is also accounted for, in the setting of the guitar's intonation. However miniscule this measurement is, it does get accounted for in fret spacing. Of course, those who play with noticably high string action will notice some tuning problems when fretting around the 3rd fret compared to fretting up above, say, the 19th fret.

To more accurately understand your initial question, I assume you're asking more along the lines of necessary force to keep the fret from buzzing, right? That's simply enough force or compression to keep the vibrations of the string below the fret. You want to dampen the vibrations of the string to an almost infinite situation, where it just doesn't vibrate, it stops the string's vibration right at the fret. We've all played a note too loosely and felt the note buzz underneath our fingers. Cuz we didn't dampen the string's vibration into the fret strongly enough.

Yes, we need a minimum pressure on the string, to dampen and terminate the string's vibrations into the fret. At that point, all vibrations are transferred into the wood of the guitar neck.

BUT YES, since the strings above the fret or above the nut are attached to the guitar, some of those sympathetic vibrations can travel up the neck as well as down the neck. They CAN vibrate the strings above the nut. There's no such thing as being able to completely isolate any vibrations below the fretted note. Otherwise, Fat Finger would be out of business!

This would go towards explaining why an angle that suits one string gauge or type of instrument may not be suitable for another - although perhaps I'm just grasping at straws.

More like why one string gauge needs to feel tighter than another just to get the same pitch. A thin gauge wire needs less tension to hit a certain pitch, for the same length. A thicker wire needs more tension, because the added mass vibrates slower at the same amount of tension.

It's an old wives tale, that any gauge set of strings is innappropriate for any particular guitar, or any particular gauge set of strings works best for any particular guitar. To the player, one gauge set might FEEL more comfortable, SOUND better, PERFORM more desirably... to HIS hands. For example... Angus Young uses 12's and 13's on his guitars. I know guitarists who have tried to string up one of their guitars with the towing cable sized monsters. Their hands were too weak to handle all that excess tension and super-stiff strings, their guitars needed tons more internal force from their truss rods to handle the now supertight strings, and their nuts needed to be filed wider so their strings didn't bind and pinch in the slots. Just that alone, is already three very subjective conditions that can change from player to player and guitar to guitar.

I also wonder why I get a sympathetic ringing of the strings past the bridge on my jaguar-trem equipped guitar, (not audible through the amp unless at high gains) although the angle over the bridge is greater than the angle over the nut in guitars - I assume this in part is a different aspect at play, but I wonder if the force exerted at that angle would effect this.

As explained above, it's vibrations bouncing back up into the strings, from the wood of the guitar.

Sidenote: I've actually tuned a bass before, just by feeling the waves of vibrations in the headstock. Fretted the 5th fret and open string, plucked em, then reached over to feel the headstock as I held the notes. Vibrations ar AWESOME, DOOD OMG***LOLBBQ

And it veers into the realm of mojo, but are there tonal reasons for differences in angle?

Yup. Chicken bone, chicken bone, lucky lucky chicken bone! Naw, dude, I'm sure there's some serious science behind it, and some voodoo superstitions as well. All'z I can say is, I HATE Fender style headstocks and greatly prefer an actual angle to my headstocks to create the break angle over the nut. Fender's style was simply a cost-effective solution, by adding some steel bars to force the strings to bend over the nut. I'ma go with all the HUNDREDS of years of violins, cellos, violas and double basses whose luthiers have done it before Fender decided to get economical with their lumber usage.

I'm really overthinking this - I ought to just go make some measurements of the angle over the nut on a variety of known-functional designs from store bought guitars, take that into consideration when designing a headstock and make sure that nothing about by placement causes a radical difference in these angles. Removal of string trees on Fender-style instruments ought to give me an idea of what to look at avoiding.

You could also get a few beers and turn on Ninja Warrior and say screw it! Heh heh. Just build it at 15 degrees like everyone else gets away with, and all that extra worry time could be converted to relax time!

But... what if you built three different necks? Or at least... mockups of necks? Use cheap crappy tuners, get some nuts, make a 2x4 neck and cut the necks at 12, 15, and 18 degrees, and see how it feels? I know... playing devil's advocate. But why not? It would, at least, make a cool thread filled with lots of pictures for us, in the name of posterity.

And cold beers.

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