# Fretboard Geometry

Nick JD
April 22nd, 2011, 10:57 PM
Warning: Mathematics content! Anal levels of analysis content! This is not intended to change any techniques or minds, rather to prompt discussion and deeper understanding.

Two things that I'd like to bring up. Firstly, I think neck relief is a band-aid solution for an incorrectly set up (made) neck. Secondly, that while most level and crown techniques improve a set up by miles, they can almost always be done perfectly with one simple tweak.

A Stew Mac article talking about neck geometry here (http://www.stewmac.com/freeinfo/Neck_relief,_building_and_repair/a-compoundradius.html) gives a few simple equations to calculate the optimum neck geometry for a perfect neck set up. I'd like to discuss these equations and their outcome with regard to neck set up methods and leveling and crowning techniques.

For a long time I was puzzled by a few of the methods and in general the geometry of the whole neck. Since delving into it I have had a couple of revalations that I'd like to share if you can bear with me.

Here's the first equation (I've linked it off their site because it's got the diagram there too).

This first equation above is not really important, but it's needed to solve the next equation. So we plug the numbers in and solve X.

T = half the scale length = 12.75
St = the width at the 12th fret = 2.05
Sn = width at the nut = 1.67

When we plug those into that equation we get X = 56

Now we have X, we can use it to find what the radius should be at the 21st fret in order to have the strings all the same distance above their frets. What is the optimum conical radius for the lowest possible action without buzzing in a standard Fender 9.5" nut radius neck with zero relief?

We need to solve equation number 2. We need to find Rd for a Fender neck.

Rn = the radius at the nut = 9.5
X = 56
D = the distance between the nut and the 21st fret = 17.92

When we plug these numbers into the equation we get 12.54 ... or a 12.54" radius at the 21st fret being the optimum conical radius for a 9.5" nut radius Fender neck.

That was a lot of numbers, but what does it mean in the real world? Here goes:

For the E string and the D string to both have the same action as each other off the frets, the neck radius needs to change from 9.5" at the nut to 12.54" at the 21st fret. In other words, if the radius is a constant 9.5" all the way up the neck, the strings simply can not have the same distance above the frets above each fret - one can (either the D or the E), but not both. You can either adjust the trussrod to have the E string's frets underneath it exactly where they need to be, or, the D strings ... unless you have a conical radius.

So armed with your fret leveling beam, do you adjust the neck to be straight in the middle (the D string path)? Most people do. But the math above clearly shows that it is impossible to level the string paths for all the strings unless you have a 9.5 - 12" conical radius.

So how to get a prefect level and crown on a constant radius - put a conical radius in it. Adjust the neck so it is straight -- at the E and e string paths -- and is slight off straight in the middle, at the D and G string paths. Then the leveling process will remove excess material from the 12th to 21st frets effectively giving them a 12.5" radius and allowing your strings to be exactly evenly the same distance off the frets all the way up the board.

Continued in part Two: how does this relate to a 7.25" vintage radius with low action fretting out with bends in the 12th to 21st frets? And how does this relate to the radius to which we set our saddles?

LeroyBlues
April 22nd, 2011, 11:15 PM
Good stuff. Thanks Nick

Nick JD
April 23rd, 2011, 12:23 AM
If we run the numbers again for a 7.25" radius neck, we get an optimum 21st fret radius of 9.57".

I've made these comparison pictures of a 7.25" and a 9.5" radius overlaid to illustrate the difference between the two. Quite a lot. You can see that above the 12th fret, where optimally you want an increasing radius to 9.5" ... you are bending up a big 7.25" hill, and it's causing the note to deaden on the fret in front.

It's not really possible to put a conical radius in a vintage radius neck with a level and crown - the difference between 7.25 and 9.57 is too great.

http://i841.photobucket.com/albums/zz334/nickjdo/7n9.jpg

Let's compare this same 2" difference in radius with a 14" and a 16".

http://i841.photobucket.com/albums/zz334/nickjdo/14n16.jpg

Virtually no difference. The bigger the radius gets, the less the difference becomes - and the less important a conical radius becomes for a low action.

So, if the 21st fret should be a couple of inches flatter (roughly, for Fenders) than the nut, what should the saddle radius be?

Using the equations above for a 9.5" Fender neck we get 13.8".

Nick JD
April 23rd, 2011, 12:42 AM
Good stuff. Thanks Nick

No worries - I'm only just coming to terms with all of this. My brain hurts :mrgreen:.

Keyser Soze
April 23rd, 2011, 10:44 AM
Ken Parker talks about this in an interview he did with ToneQuest Report. The ideal relationship is defined by the radius at the nut and the radius at the bridge, or really, any other single defined point along the string length. But once you have chosen those two points they determine what everything else should be.

http://www.tonequest.com/articles/article23.htm

TQR: How did you arrive at the fretboard radius for your guitars?

On any stringed instrument where the string spacing is wider at the bridge than it is at the neck, the surface of a correct fingerboard is a cone and not a cylinder. It’s a section of a paper coffee cup, not a soda can. In that event, the arc on the fingerboard is different everywhere. It changes.

TQR: You’re saying it should change, ideally…

It has to change…in order for it to be correct. The big manufacturers have never used conical surfaces – they never have. One of he reasons to refret a guitar is to flatten the end of the fretboard so it doesn’t fret out when you bend strings. They fret out because they’re too curved up there and if they are built correctly they won’t fret out. So in common guitarspeak, there are two phrases that are used to describe the arc of a fingerboard. Geometry is pretty cut and dried…how about the phrase compound radius? This is a term of nonsense – it has absolutely no meaning. A radius is the straight line measurement between the center of a circle and the outside of a circle, as you know. It is no more or less than a straight line, and you cannot compound a straight line. It’s geometrical nonsense, like saying a flat curve or a straight circle. What it’s intended to convey is the notion of a conical surface. Every violin that was ever made has this combination of shape. On a guitar that’s correctly set up, the arc is from a smaller circle at the nut than it is at the bridge, and that’s what people are trying to say when they use the term compound radius.

TQR: So what are you using on the Fly? I was at a shop earlier today and asked what the fretboard radius on a Strat I had with me was, and the guy just pulled out a Stew-Mac plastic template gauge – I was expecting something more interesting and complex as an answer…

If you had a good guitar repairman and he refretted your guitar, when he was finished you would have a conical section. Not because he would get out templates necessarily (although if you subscribe to the Stew-Mac style you have to have a template to blow your nose), but just to accommodate the string. If you corrected the fretboard surface so that all the strings were happy, you’d end up with a conical surface. The reason is that there is no string on a six-string guitar that is parallel to the centerline.

Where things become less than ideal is when we acknowledge that each string is not identical to the others and therefore each will have a different amplitude of vibration. Heavier strings simply demand a higher action, or some relief. But there is nothing wrong with this, we are simply treating each string as it should be treated - individually. We do this when cutting nut slots too.

In my own experiece when doing a setup I will start with a totally straight neck and try to achieve a good action by slightly flattening the radius at the bridge (thereby raising the action of the strings with the largest amplitude) and only if that is not working out (when the strings get too high far up on the neck intonation can be compromised) will I start adding any relief.

Not that relief is necessarily bad, but as you allude to, it does significantly complicate the geometry. Once you go down that route the whole thing becomes very seat-of-the-pants.

Sharp5
April 23rd, 2011, 11:30 AM
Makes sense. I think.

So how does one do this? With different radius blocks or after it is fretted with a beam?

I'll have to check out the article to see if it says how Parker does this. I do respect the fact that he is not tied to tradition and is advancing the field.

piece of ash
April 23rd, 2011, 11:44 AM
Boy... he sure gets worked-up about the term compound radius... too much coffee maybe... or doesn't like interviewers.

piece of ash
April 23rd, 2011, 11:54 AM
This is how I do it...

1) The level is being used as a sanding beam... simply because it has a nice machined straight surface. It has sticky sandpaper on the bottom.

2) Notice the rollers and support glide at the far end of the sanding beam. This keeps the beam traveling through a single point at all times. The distance from the pivot glide to the nut is calc'd using the formulas Nick JD has provided.

3) The neck is checked periodically throughout the sanding process using a a radius gauge at predetermined location.

4) I use dressmakers chalk to put a series of hash-marks across the fretboard... so you can determine easily when the sanding has leveled (or "coned" we should say) the entire surface.

5) I shaved my wookie hand for the photo.

Jack Knife
April 23rd, 2011, 03:34 PM
That's a nice jig you've rigged up, piece!

piece of ash
April 23rd, 2011, 03:42 PM
Thanks... I'm going to build a "real" one once I give it some more thought. That was sort of a thrown together kluge... just to see if'n i'd work. That's a Jazz bass neck getting a fretless Ebony fretbo... oops FINGERBOARD installed.

And BTW... those levels are available at Home Depot... maybe Lowe's too. They actually have a machined edge that my precison rule says is straight. There is a Momma bear version as well... so another alternative for a fret leveler. A little on the spendy side though.

Keyser Soze
April 23rd, 2011, 04:06 PM
Boy... he sure gets worked-up about the term compound radius... too much coffee maybe... or doesn't like interviewers.

Yeah, but his crack about needing a template to blow your nose being the 'Stew-Mac' way is priceless.

FWIW, I've only re-radiused existing fretboards - using a method very similar to Piece of Ash's. You work along the position of each string, moving up and down the fretboard. Which actually creates a series of bevels that can then be smoothed into something approaching a cone. It's not exact, but it really doesn't need to be exact. Again, primarily because we are actually treating each string independently, but also because ultimately it is the frets we are concerned with (and through the fretting process each fret naturally forms a 'better' curve.

Heck, if you are one who tends to press harder with the beam on higher frets during the levelling process that alone can create sufficient 'compound' if you are starting from a relatively flat radius neck (e.g. 12" or such.)

Edit: and those are the exact same beams I use. Buy two, and a small jar of 150 grit valve grinding compound. Slather one with the compound, lay them side by side on a flat surface, mate the two together, then using long even strokes rub back and forth to polish them both into perfectly smooth flats.

e-merlin
April 23rd, 2011, 04:07 PM
So, how do arthritic fingers and wrists play into the numbers? How about personal preference?

This is why eggheads will never solve the world's problems.

piece of ash
April 23rd, 2011, 04:17 PM
Keyser... I have been wondering if one should proportion the radius to match the spread of the string... by doing so... you would make the strings parallel to the "axis" of the cone.

e-merlin... the 2011 AM DLX Strats and Teles have compound fretboards... I'd go try one out. Not to mention that the quality of Fender AM necks is pretty danged high as well. You could get one off Ebay or Warmoth makes them too.

Jack Knife
April 23rd, 2011, 04:21 PM
But the math above clearly shows that it is impossible to level the string paths for all the strings unless you have a 9.5 - 12" conical radius.

Maybe that's why I liked my Mighty Mite compound radius neck so much? They have a 9.5-12 compound.

murrmac123
April 23rd, 2011, 04:42 PM
Edit: and those are the exact same beams I use. Buy two, and a small jar of 150 grit valve grinding compound. Slather one with the compound, lay them side by side on a flat surface, mate the two together, then using long even strokes rub back and forth to polish them both into perfectly smooth flats.

This is a great thread, and I will be coming back to it, but, Keyser, forgive me for being pedantic, but I have to point out that the process you describe is not actually guaranteed to give you two absolutely flat surfaces. You could conceivably end up with one concave and one convex surface. To guarantee straightness and flatness, you would need three beams, and lap them all one against the other in the order A:B, A:C, B:A, B:C, C:A, C:B, A':B, A':C, B':A, B':C, C':A, C':B, where A' denotes A reversed. If the process is repeated a couple of times (perhaps with finer abrasives) , you will inevitably end up with three perfectly flat, straight surfaces.

OK, back to fretboard geometry ...:razz:

e-merlin
April 23rd, 2011, 04:46 PM
Keyser... I have been wondering if one should proportion the radius to match the spread of the string... by doing so... you would make the strings parallel to the "axis" of the cone.

e-merlin... the 2011 AM DLX Strats and Teles have compound fretboards... I'd go try one out. Not to mention that the quality of Fender AM necks is pretty danged high as well. You could get one off Ebay or Warmoth makes them too.

I've owned several guitars with Warmoth or other compound radius necks. I speak from experience.

Nick JD
April 23rd, 2011, 07:51 PM
My point in this thread was more along the lines of: you can put a perfect conical radius in a 12" constant radius guitar's frets.

Without realising, on fretboards with a radius greater than 9.5", a fret level is also a conical radiusing ... because the only way to take a tiny bit off each and every fret (marking the sharpie line) while following the string paths is to make the neck conical.

This can be done in two ways: either by decreasing the radius towards the nut, or increasing it towards the heel. Otherwise the neck isn't being leveled properly.

This is why an L&C plays so nicely, as much as getting rid of those few high frets.

The OP wasn't about compound radius boards. :grin: But it does show that the perfect compound radius is a 9.5 to 12.54, or a 7.25 to 9.57...

...or a 14 to 14 with a quick wipe of the leveling beam :wink:.

piece of ash
April 23rd, 2011, 08:04 PM
So, how do arthritic fingers and wrists play into the numbers? How about personal preference?

This is why eggheads will never solve the world's problems.

I've owned several guitars with Warmoth or other compound radius necks. I speak from experience.

You speak from experience... What are you speaking of? I'm confused...

piece of ash
April 23rd, 2011, 08:11 PM
I see what you're driving at Nick.

Because if we were truly maintaining a perfect constant cylinderical radius, the leveling beam would have to be over/past the ends of the frets, off the neck completely on the nut end, when leveling the ends of the fret on the heel end.

Good point!

e-merlin
April 23rd, 2011, 09:16 PM
You speak from experience... What are you speaking of? I'm confused...

If you weren't fishing for an argument you would have quoted yourself when you said:

e-merlin... the 2011 AM DLX Strats and Teles have compound fretboards... I'd go try one out. Not to mention that the quality of Fender AM necks is pretty danged high as well. You could get one off Ebay or Warmoth makes them too.

Oh, look how easy that was. Fret no more, I got you covered. So as not to further impinge on the integrety or intent of this thread, I'm out.

piece of ash
April 23rd, 2011, 09:37 PM
I'm not fishing for an argument. Perhaps one of your posts was deleted. I see 2 questions and 3 statements.

I had no specific knowledge of how a compound fretboard might work with arthritic fingers. Assuming that those arthritic fingers were yours, and respecting your right to preference, I simply advised where you might easily try one of these necks out.

If I'm reading between the lines correctly at this point, it is clear that you have tried these fretboards and your 2 questions were simply a rhetorical way of expressing your dislike for them. I was just taking you seriously.

Follow what Nick is saying here... it is perfectly clear that any fretboard that has been beam leveled has inescapably acquired a compound radius in the process.

Miopic Chitlin
April 23rd, 2011, 09:45 PM
This is why I don't do necks. The lottery is for people who don't know math, and I play the lottery...a lot.:roll:

Bolide
April 23rd, 2011, 09:51 PM
I also drank way too much coffee today, but this is a great thread.
I'm onboard with almost everything, and will do some cogitationinizoning before asking the question that is not quite fully formed within my shiny ovoid cranium.

genesiospinola
April 24th, 2011, 11:03 AM
Warning: Mathematics content! Anal levels of analysis content! This is not intended to change any techniques or minds, rather to prompt discussion and deeper understanding.

Two things that I'd like to bring up. Firstly, I think neck relief is a band-aid solution for an incorrectly set up (made) neck. Secondly, that while most level and crown techniques improve a set up by miles, they can almost always be done perfectly with one simple tweak.

A Stew Mac article talking about neck geometry here (http://www.stewmac.com/freeinfo/Neck_relief,_building_and_repair/a-compoundradius.html) gives a few simple equations to calculate the optimum neck geometry for a perfect neck set up. I'd like to discuss these equations and their outcome with regard to neck set up methods and leveling and crowning techniques.

For a long time I was puzzled by a few of the methods and in general the geometry of the whole neck. Since delving into it I have had a couple of revalations that I'd like to share if you can bear with me.

Here's the first equation (I've linked it off their site because it's got the diagram there too).

This first equation above is not really important, but it's needed to solve the next equation. So we plug the numbers in and solve X.

T = half the scale length = 12.75
St = the width at the 12th fret = 2.05
Sn = width at the nut = 1.67

When we plug those into that equation we get X = 56

Now we have X, we can use it to find what the radius should be at the 21st fret in order to have the strings all the same distance above their frets. What is the optimum conical radius for the lowest possible action without buzzing in a standard Fender 9.5" nut radius neck with zero relief?

We need to solve equation number 2. We need to find Rd for a Fender neck.

Rn = the radius at the nut = 9.5
X = 56
D = the distance between the nut and the 21st fret = 17.92

When we plug these numbers into the equation we get 12.54 ... or a 12.54" radius at the 21st fret being the optimum conical radius for a 9.5" nut radius Fender neck.

That was a lot of numbers, but what does it mean in the real world? Here goes:

For the E string and the D string to both have the same action as each other off the frets, the neck radius needs to change from 9.5" at the nut to 12.54" at the 21st fret. In other words, if the radius is a constant 9.5" all the way up the neck, the strings simply can not have the same distance above the frets above each fret - one can (either the D or the E), but not both. You can either adjust the trussrod to have the E string's frets underneath it exactly where they need to be, or, the D strings ... unless you have a conical radius.

So armed with your fret leveling beam, do you adjust the neck to be straight in the middle (the D string path)? Most people do. But the math above clearly shows that it is impossible to level the string paths for all the strings unless you have a 9.5 - 12" conical radius.

So how to get a prefect level and crown on a constant radius - put a conical radius in it. Adjust the neck so it is straight -- at the E and e string paths -- and is slight off straight in the middle, at the D and G string paths. Then the leveling process will remove excess material from the 12th to 21st frets effectively giving them a 12.5" radius and allowing your strings to be exactly evenly the same distance off the frets all the way up the board.

Continued in part Two: how does this relate to a 7.25" vintage radius with low action fretting out with bends in the 12th to 21st frets? And how does this relate to the radius to which we set our saddles?

Hi Nick! How are you my friend?! Great thread! But, one question...The strings radius at the nut is not 9,5" to put in the formula. Do you know what i mean. The slots heights at the nut are differents and do not do a 9,5" radius. High "e" to low "E" we have to increase like 0,002" by string. The amplitudes of vibration of the strings are different, had to its thicknesses. BUT, i know that thinking the fretborad as a cone is the correct way! Let's think about this. For me the ideal would be to put the 6 strings heights at the nut in another program to find the correct "radius", or i think that is not yet a radius anymore, i'll be a curve "goin up".
Cheers Nick!

Keyser Soze
April 24th, 2011, 11:28 AM
Keyser... I have been wondering if one should proportion the radius to match the spread of the string... by doing so... you would make the strings parallel to the "axis" of the cone...

That is exactly what Ken Parker was getting at in his comments. The fact that the string spread out laterally due to the changing width between nut and bridge means that the frets/fretboard must either be perfectly flat (infinite radius), or must must describe a cone in order to maintain any sort of even relationship between each string and the fret as we move up the fretboard.

piece of ash
April 24th, 2011, 11:51 AM
Yes Keyser. It occured to me somewhere along the line that if you wind up with the geometry Nick is talking about because you "beamed the frets" relative to the string paths and fretboard edges, you have effectively cut a compound radius on the frets that is proportional to the string spread.

So compound geometry is cool... but like many things they went to far? I mean a 10-16 radius... a ratio 1/1.6... that's more than the ratio of string spread. I'll have to play with this in AutoCad... I don't know if I want my silly fixture to be 18 feet long!

And I don't want to know what those blue levels cost at that length...

Keyser Soze
April 24th, 2011, 04:45 PM
Actually, I think 10"-16" is not 'too' far. But it is about as far as you can go without the feature descending into irrelevancy.

Like Nick noted, once the starting (nut) radius gets up around 12" or higher the relative changes in ideal shape can rapidly be overwhelmed by the changes necessary due to other issues (amplitude of heavy strings, the inherent flex of an organic hunk of fiber, etc.) Or, again due to the really small actual differences, the feature can be created solely through fret level/dress technique.

To my mind the compound radius is most useful for people (such as me) who like the smaller Fender radius low on the neck (for barre's and thumb over technique) because it is about the only way to get a decently low action up high.

murrmac123
April 24th, 2011, 04:47 PM
This is indeed a great thread, well done, Nick.

I am going to throw in a piece of trivia which is of absolutely no practical use, but which might provide ammunition for some arcane discussions over a few beers ...or maybe not ...

In a constant radius fret board, the fret slots follow a true arc of a circle, but in a conical fretboard, they cannot follow a true arc of a circle, instead, they follow the arc of an ellipse.

There, I did say it was of no practical use ...

David Collins
April 24th, 2011, 04:59 PM
The formulas there are all great and interesting, but in practice can be greatly simplified.

If you want the board to represent a truly conical section (mostly for ease of machining while keeping a straight line beneath each string), then there is one simple rule to follow.

The radius should remain directly proportional to the string spacing.

That's it. Radius A / Spacing A = Radius B / Spacing B. If your string spacing is 1.5" at the nut with a 10" radius, and spreads to 1.8" at the 12th, then you have 10/1.5 = x/1.8. Solve for x, and you have your 12th fret radius at 12". Simplified formula - (Ra/Sa)*Sb=Rb

Of course you don't need your board to be a section of a true cone. That makes it convenient to shape a board on a pendulum arm, but it's not the only way to get a straight line beneath each string. You can start at 10 and end at 20, or start at 12 and end at 12 if you want, and if you level in line under each string you will still get a straight line beneath each string. If you do this of course you will not have a truly conical section, and there will in theory be no more than 2 points along the board that are shaped to a perfectly true radius, but all this is actually entirely inconsequential in the end setup. You might have to call the shape or any particular profiles a elliptical, parabolic, hyperbolic, or some other proper name for a geometrical form, but beyond that it doesn't really matter. If leveled properly, each string will still see a series of points in a straight line beneath it.

I think I may have to disagree with Ken's interview on one small point. It sounded as though he was placing the blame for fretting out on bends entirely on the lack of having a true conical section. Not sure if I read it exactly how he meant it, but if so this would not be entirely correct. When bending, it is quite simply the severity of the radius and the height of the action that determine how far you can go before fretting out. That's kind of a separate issue from the bulk of what's being discussed here though.

piece of ash
April 24th, 2011, 07:49 PM
The key things in my mind are as follows:

1) The realization that a fretboard leveled with a beam will arrive at some shape very near a conic section.

2) Knowing that this will happen would permit the fretboard to be cut to that shape prior to fretting.

I'll be fretting in stainless:

3) I have no belief in the sonic qualities of frets.

4) The best way to refret a neck is not to... use material that will last longer in the first place.

5) The more accurate the fretboard the less metal that needs to be removed. Nick's demonstrated that the amount of material in question is on the order of a sparrow's fart. But it's still stainless.

The real kicker is this:

6) If a neck made with a cyliderical radius will infact become a compound or psuedo compound radius, when beam leveled, with radius proportional to string spread... then that same logic must extend to fretboards made with compounding that exceeds the the relation of radius proportional to string spread.

Strat spread at nut: 1.4 inches

Strat spread at fret 22: 1.898

Ratio = 1.898 / 1.4 = 1.356

This in mind, it would seem that compound radius fretboards on the order of 10 to 16 have gone too far... in a complimentary sense that "normal fretboards did not go far enough.

This also means that my nifty fixture must have "focal point" 51.5 inches behind the nut... and the sanding beam needs to be 72+ inches long... dammit!

piece of ash
April 24th, 2011, 07:54 PM
murrmac123,

Perhaps we should be cutting fret slots perpendicular to the conic axis... and ditch all those all elliptical sections altogether?

Where are we going to get curve nut blanks???

And... I won't buying 3 levels and going through yet another 12 step program... thank you.

:mrgreen:

Colt W. Knight
April 24th, 2011, 07:58 PM
Who is Ken Parker?

piece of ash
April 24th, 2011, 08:04 PM
I think he is Spider Man... right?

Colt W. Knight
April 24th, 2011, 08:07 PM
I think he is Spider Man... right?

Nope thats's Hank Parker, or wait, is he the fishing guy?

piece of ash
April 24th, 2011, 08:19 PM
I'm guessing it is this guy?

http://www.parkerguitars.com/

Colt W. Knight
April 24th, 2011, 08:23 PM
I'm guessing it is this guy?

http://www.parkerguitars.com/

Or this dude

http://kenparkerarchtops.com/

piece of ash
April 24th, 2011, 08:30 PM
Pretty interesting approach on those archtops... hope his engineering is as good as his design...

No bridge adjustment... pretty cool if it works and lasts...

David Collins
April 24th, 2011, 08:31 PM
Yup, that's Ken - or at least the company he started. Not sure if he's still actively working with that line, or if he sold it off or still owns it. I believe he's focused on work with archtops now, which though I've not played any have heard marvelous things about. Ken does have a truly brilliant mind, which kind of makes me wonder if the quote from that interview may have come off not sounding exactly how he meant it.

As to the rest, I wouldn't worry about board lengths (all gets factored out) or abstract focal points. Your leveling bar only needs be as long as your board. If you start with whatever radius you want at the nut, and whatever radius you want at the end, you can easily level any errors out of a board by hand before fretting. Whether the board is a straight single radius, or a compound radius that changes too drastically for a theoretical cone section, the results will be the same. If you adjust your neck before fretting to be dead straight on it's center line, you will end up with a very slight backbow in the middle of its length along the edges. Mark the board with pencil, and start sanding with a bar (fanned to keep in line with string path as you move across) being careful not to alter the radii at the ends. The markings should disappear from the center line in a swipe or two, and you'll end up taking a hair from around the middle frets as you approach the edges. When the pencil lines are gone, you have a pretty much perfectly straight board beneath each string.

piece of ash
April 24th, 2011, 08:52 PM
Actually... did you see my jig in post #8? I had floundered around for a few hours with a StewMac sanding bean (PoS0) and got no where. Once I made the fixture with the focal point... I was done in 20 minutes... and it was flawless. Keep in mind, this was for a fretless bass... so you have to "get it right" on the wood itself... no frets to make up for this or that.

I had done fretless conversions before and found that getting good "mwah" over the whole board was tough. This guitar (mine) oozes "mwah". So the anal approach paid off.

I suspect it'll be easier to dial it in a guitar... if for no other reason than they're shorter.

Colt W. Knight
April 24th, 2011, 08:54 PM
Actually... did you see my jig in post #8? I had floundered around for a few hours with a StewMac sanding bean (PoS0) and got no where. Once I made the fixture with the focal point... I was done in 20 minutes... and it was flawless. Keep in mind, this was for a fretless bass... so you have to "get it right" on the wood itself... no frets to make up for this or that.

I had done fretless conversions before and found that getting good "mwah" over the whole board was tough. This guitar (mine) oozes "mwah". So the anal approach paid off.

I suspect it'll be easier to dial it in a guitar... if for no other reason than they're shorter.

Mwah? Are you talking about kisses?

piece of ash
April 24th, 2011, 08:58 PM
Think of the bass tone in Paul Simon's Boy in the Bubble... fretless players call it "mwah"... the notes "bloom" or swell after you pluck them... kinda the ooposite of twang

here:

EDIT: changed links... that was almost very wrong... almost

Mwah is a little like the buzz bridge on a sitar... action and relief have to dead on to get good it right. It's easier with round-wound strings... but, that's brutal on the neck.

Colt W. Knight
April 24th, 2011, 09:10 PM
Think of the bass tone in Paul Simon's Boy in the Bubble... fretless players call it "mwah"... the notes "bloom" or swell after you pluck them... kinda the ooposite of twang

here:

EDIT: changed links... that was almost very wrong... almost

Mwah is a little like the buzz bridge on a sitar... action and relief have to dead on to get good it right. It's easier with round-wound strings... but, that's brutal on the neck.

Thats what my GF uses to denote kissy sounds when she texts. :mrgreen: HAHA!

piece of ash
April 24th, 2011, 09:17 PM
Geeze... I hope too many people didn't follow the first link I posted.

The song came on... it was correct... I copied the link and posted. Surprised it's on Youtube... damn close to very inappropriate.

And keep the girl away from fretless players...

Colt W. Knight
April 24th, 2011, 09:26 PM
Geeze... I hope too many people didn't follow the first link I posted.

The song came on... it was correct... I copied the link and posted. Surprised it's on Youtube... damn close to very inappropriate.

And keep the girl away from fretless players...

http://i299.photobucket.com/albums/mm308/coltwknight/rofl2.gif

Bolide
April 24th, 2011, 09:57 PM
Hey, at least Colt had the good grace to associate "Mwah" with his girlfriend:
I thought of Carol Burnett.

piece of ash
April 24th, 2011, 10:02 PM
I would mwah Carol Burnett... I'd make her tell jokes first.

Colt W. Knight
April 24th, 2011, 10:07 PM
Think of the bass tone in Paul Simon's Boy in the Bubble... fretless players call it "mwah"... the notes "bloom" or swell after you pluck them... kinda the ooposite of twang

here:

EDIT: changed links... that was almost very wrong... almost

Mwah is a little like the buzz bridge on a sitar... action and relief have to dead on to get good it right. It's easier with round-wound strings... but, that's brutal on the neck.

I would mwah Carol Burnett... I'd make her tell jokes first.

So you would bloom and swell up for Carol Burnett?
http://i299.photobucket.com/albums/mm308/coltwknight/carol.jpg

:oops:

piece of ash
April 24th, 2011, 10:17 PM
No... just one single mwah... just to say I did...

Thinlineggman
April 24th, 2011, 10:22 PM
Oops

Nick JD
April 26th, 2011, 09:59 PM
Segue of the century! Fretboard geometry ... Carol Burnett!

piece of ash
April 26th, 2011, 10:30 PM
Well... I think we got the fretboard geomtery thing down... thanks Nick!

Carol Burnett was just the next most obvious thing really.

Al Watsky
April 26th, 2011, 11:21 PM
Thats how your sposed' to plane the board.
You won't get what you want with the fret alone.
You can but it feels funny as the frets are different heights in different ranges.
Its a compound relief situation as well as a compound radius.
Bingo.

Nick JD
April 27th, 2011, 01:10 AM
Thanks Al.

I thought I'd completely wasted my time. Where were you before when we needed your wisdom?

Playing bingo?

Al Watsky
April 27th, 2011, 01:21 AM
Thanks Al.

I thought I'd completely wasted my time. Where were you before when we needed your wisdom?

Playing bingo?

Out of the loop for a few days.

piece of ash
April 27th, 2011, 01:26 AM
Al,

What is that little taco lookin' thing in the signature line?

Al Watsky
April 27th, 2011, 01:29 AM
[/ATTACH]Al,

What is that little taco lookin' thing in the signature line?

You mean my fret file ?
Its used mainly on fret ends, but you can do light leveling with it too.
Pretty common tool for fret work.81498
Mine has some wear on it . Its a double cut metal file sliced in half and epoxy glued to a scrap and belt sanded.

piece of ash
April 27th, 2011, 01:34 AM
OK... I get it now... not something a wookiee would eat.

Al Watsky
April 27th, 2011, 01:36 AM
OK... I get it now... not something a wookiee would eat.

Not good eatin'....:shock: Give ya' heart burn.:neutral:

Nick JD
April 27th, 2011, 03:16 AM
Out of the loop for a few days.

While you were out, I did a level on a 12" radius board and turned it into a conical radius, even though you said it wasn't possible. :wink:

Go back and read my OP. You will see that I've outlined which radiuses can be made conical with a leveling beam and which ones cannot - and that any properly-done fret leveling must create a conical radius.

Have a read of the Parker interview stuff in this thread while you're at it, where violin fingerboards are mentioned.

If you feel you have to disagree with the basis of this, please do - but please substantiate your line of thinking rather than making blunt statements followed by grey-haired gambling jargon, if you could. :grin:

Al Watsky
April 27th, 2011, 10:41 AM
While you were out, I did a level on a 12" radius board and turned it into a conical radius, even though you said it wasn't possible. :wink:

Go back and read my OP. You will see that I've outlined which radiuses can be made conical with a leveling beam and which ones cannot - and that any properly-done fret leveling must create a conical radius.

Have a read of the Parker interview stuff in this thread while you're at it, where violin fingerboards are mentioned.

If you feel you have to disagree with the basis of this, please do - but please substantiate your line of thinking rather than making blunt statements followed by grey-haired gambling jargon, if you could. :grin:

Sorry, I was agreeing with you in principal ! I didn't think I was saying it wasn't possible. Its difficult to carry out , not impossible. I'll give the posts a re-read.

Al Watsky
April 28th, 2011, 01:00 PM
Conical radius is a wonderful idea.
Its a more accurate idea in theory than compound radius.
When you apply the Idea to an actual neck you quickly find that other factors mitigate the pure math of the OP.
The different dimensions of the strings require differing amounts of relief so the need in practice to apply that to the fingerboard prevents the the carrying out of the "pure" concept.
There are many factors involved , radius is one and relief is the other, fall away another. When you attempt to mill the board prior to fretting you have to attempt to achieve perfection on a wood surface to within some few thousandths of an inch.
Its tricky but it can be done.
I use beams to level and then spot sand with shorter blocks to establish the compound relief and fall away , the "conical" aspect of the radius is more or less subsumed in the necessity of perfecting the compound relief and fall away.
Then the frets are installed , by what ever method is preferred and they are leveled in the usual manner.
Some of the fine tuning can be obviated by the leveling so care must be taken to seat the frets well which hopefully will minimize the need to level.
Then after the instrument has been played enough to require a new level and crown the preparation of the board needs to be taken into account to maintain the profile. Not a big problem actually.
Like I said "bingo" !

megafiddle
April 28th, 2011, 09:51 PM
It's nice to know just what the numbers are. I worked some out with
a small program.

So, for a 25.5" scale, 10" radius, 1.4 inch string spacing at nut, 2.06 spacing at bridge,
and a perfect cylindrical straight neck (fret surface), I get the following:

Fret surface at middle of neck under either E string is 0.0006" higher than at ends of neck.
Less than one thousanth of an inch. For a 7.5 " radius it's still only 0.0008" high
under string at middle of neck.

This with the neck dead straight. Also .010" at 1st fret and .040" at 22nd fret.

This pretty much agrees with numbers I worked out on separately on paper. It's
not a hard calculation.

I should say the middle of the fretboard is closer to the string by .0006", not higher.

Nick JD
April 28th, 2011, 11:51 PM
Conical radius is a wonderful idea.
Its a more accurate idea in theory than compound radius.

http://i1128.photobucket.com/albums/m482/DootDoots/random4tehnetz/Screenshot2011-03-29at121453.png

And just so you're aware, Al - the math in the OP isn't intended to push aside common sense and your particular method of achieving what you need to achieve. It's there to help understand and illustrate a often-misunderstood part of guitar setup.

djlogan33
April 29th, 2011, 12:03 AM

Keyser Soze
April 29th, 2011, 02:28 AM
Actually... did you see my jig in post #8? I had floundered around for a few hours with a StewMac sanding bean (PoS0) and got no where. Once I made the fixture with the focal point... I was done in 20 minutes... and it was flawless. Keep in mind, this was for a fretless bass... so you have to "get it right" on the wood itself... no frets to make up for this or that.

I had done fretless conversions before and found that getting good "mwah" over the whole board was tough. This guitar (mine) oozes "mwah". So the anal approach paid off.

I suspect it'll be easier to dial it in a guitar... if for no other reason than they're shorter.

I've never heard that sound of a fretless instrument described using that term, but had always thought of it much like that achieved by use a trumpet mute. Not coincidentally there is a particular type of trumpet mute that is called a wah-wah (Harmon.)

So your term makes perfect historic as well as onomatopoeic sense.

murrmac123
April 29th, 2011, 06:19 AM
http://i1128.photobucket.com/albums/m482/DootDoots/random4tehnetz/Screenshot2011-03-29at121453.png

And just so you're aware, Al - the math in the OP isn't intended to push aside common sense and your particular method of achieving what you need to achieve. It's there to help understand and illustrate a often-misunderstood part of guitar setup.

That is an interesting image, Nick, may I ask where you got it from ? Did you draw it yourself?

Theoretically, the fretboard section on the right is the only one on which the frets will follow a truly circular arc on the board, in the left hand
example, the frets will follow an elliptical path.

The difference is too small to be of any significance for all practical purposes, but it is still worth noting.

Al Watsky
April 29th, 2011, 09:08 AM
http://i1128.photobucket.com/albums/m482/DootDoots/random4tehnetz/Screenshot2011-03-29at121453.png

And just so you're aware, Al - the math in the OP isn't intended to push aside common sense and your particular method of achieving what you need to achieve. It's there to help understand and illustrate a often-misunderstood part of guitar setup.

JD, :lol: Happy to be in the conversation. I enjoy set up theory as much as the next guy. Its all about raising the level of thinking about set up and guitar in general.

piece of ash
April 29th, 2011, 10:39 AM
onomatopoeic

Keyser, that's a big word. What do you suppose yokoonomatopoeia refers to?

Keyser Soze
April 29th, 2011, 01:16 PM
Keyser, that's a big word. What do you suppose yokoonomatopoeia refers to?

Any horribly shrill sound emanating from the singularly despised spouse of a former Beatle. Or, more generally, any sound that closely resembles that.

Bolide
April 29th, 2011, 02:04 PM
♫ One! Singularly despised spouse, every little step she takes.
One! Shrilling combination: Every move that she makes.♪

murrmac123
April 29th, 2011, 08:37 PM
Conical radius is a wonderful idea.
There are many factors involved , radius is one and relief is the other, fall away another. When you attempt to mill the board prior to fretting you have to attempt to achieve perfection on a wood surface to within some few thousandths of an inch.
Its tricky but it can be done.
I use beams to level and then spot sand with shorter blocks to establish the compound relief and fall away

Why not just do as everybody else does and mill the fall away into the frets, (with the fretboard sanded dead straight )?

You only need a few thou fall away, it seems like an unnecessarily long-winded way to go about it to sand the fall away into the wood.

Nick JD
April 29th, 2011, 09:36 PM
That is an interesting image, Nick, may I ask where you got it from ? Did you draw it yourself?

I got it from google images looking for a good descriptor for conical and compound radiuses - someone versed in Rhino did it. Might have even been a bass player! Can't remember now - but thanks goes to him, not me.

Good to see we've got down to the "splitting hairs" end of fretboard setup. I think we might have even got into the territory between perfect, and superlative playing necks.

Al Watsky
April 30th, 2011, 09:24 PM
Why not just do as everybody else does and mill the fall away into the frets, (with the fretboard sanded dead straight )?

You only need a few thou fall away, it seems like an unnecessarily long-winded way to go about it to sand the fall away into the wood.

I don't understand your comment "long winded" but thats cool.
The dead straight thing is a starting point.
When I learned to fret it was often with much smaller wire than is the current trend. Milling a fall away into the frets lowers their life and changes the feel of the guitar as you ascend the neck. Not much of in issue for some but still a factor. Milling the frets for fall away is another workable method.
I'm not into the dead straight board any way and have my own methods that follow traditional guidelines with the acoustic instrument as a starting point.
My board milling varies from instrument to instrument. Often vintage stuff is remove and replace.
If I'm milling for a "rise" I do so till straight and may split the difference between getting a couple thou' from the board and a couple thou' from the fret.
I like all frets to be the same height thats the feel I like. Especially on an electric guitar, all the same height and as high as possible. (for my personal guitars I prefer a higher wire)
As I said its a variable.
My starting point in the trade was to a large degree in the classical guitar world.
The boards can be as much as a quarter inch thick (in blank form) to begin with and the wire especially back in the day was very low.
I learned to work the board and maintain the fret height. It was a very successful approach.
When an instrument is intended for acoustic performance in medium size halls , things go differently than when refretting an electric meant to be setup with the lowest possible action with tiny strings and played through a Marshall stack. Board planing can go to an extreme never seen on electrics.
I have 4 instruments in different stages of refretting at the moment.
Every one uses a different board prep. method , it all depends on the instrument and needs of the player and the build method, which is the variable , because they are all from different builders.