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Hey folks, glutton for punishment! Another smackdown opportunity!

I've purchased _Electric Guitar and Bass Design_ (Leo Lospennato). I have a question about something he says. I've scanned and uploaded the entire 3-page section so you can consider his comments in context. If you want to read them, here are the links:

1st page: https://drive.google.com/file/d/1x5dZAA ... sp=sharing
2nd page: https://drive.google.com/file/d/1OjVz7B ... sp=sharing
3rd page: https://drive.google.com/file/d/1tlCrVB ... sp=sharing

The item I'm concerned with is on the top of the third page (book page 94): "...in constant-radius fretboards it is necessary to keep the action relatively high: to avoid buzzes, especially in the outer strings. A compound radius fretboard minimizes this problem."

Well, OK, if that's true, then I want a neck with a compound radius. But is that actually correct? (He tries to support that contention on the 2nd page, but his diagrams just confuse me; as far as I can tell, he shows the strings going diagonally across the fretboard, but of course they don't do that, they go up in a straight line.) Anyhow, if a compound radius does allow reduced action, then why aren't a lot more mass-manufactured fingerboards made in compound radius? In the third paragraph on that same page, he goes on to say that "compound radius [sic; should be "radiuses" or "radii"] are available for CNC-produced fretboards only; is [sic again] one of those things in lutherie that machines do better, faster, and cheaper." OK, fine, but since most available guitars are now made in factories with machines, there shouldn't be any barrier to making their necks with compound radii, right? 'Cuz if they really do make for better action, then a lot of players would want them. But apparently the demand isn't there, which suggests that they don't make for better action after all. So something seems off here, though of course it may just be my convoluted thought process and my reasoning might be like Swiss cheese.

Maybe it has to do with what he then says in the fourth paragraph: "However, according to researchers in this area . . . the differences between cylindrical and conical section fretboards . . . are so small as to fall within the tolerances of competent fretwork." Not sure exactly what he means by "tolerances of competent fretwork", but the gist of this last statement seems to bely his earlier assertion that compound radii make for lower action.

Can y'all untangle this knot of confusion for me? Maybe this is yet another example of newfangled innovation not being a very good idea after all, but

BTW, in case the answer to this question depends on the specs of individual necks (as viewtopic.php?p=710363#p710363 may indicate), here are the details. Unfortunately I haven't made a final decision on some major issues, viz:

I'm not sure whether I'm going to go with Fender or Gibson scale, as I'd prefer a PRS-type 25" scale but Warmoth doesn't offer that. Right now I'm vacillating because I like wider frets up high than Gibson offers, but I also want the looser action of the shorter scale length. Right now I'm toying with the notion of getting a neck with the Fender scale and making up for the tighter tension by using those superlight Billy-Gibbons 07s. There's a good review at https://www.youtube.com/watch?v=KlZ7CzJ2VOs from a guy whose assessments I tend to agree with, so I figure it's worth a try. I play light and use 9s as it is, so adjusting to the 7s shouldn't be too much of a stretch. But then again those superlight strings mean the string ellipse is bigger so the action has to be higher, right? But I'm a really light touch so I can play instruments with buzzing that's minimal for me but which turns into Godzilla roars under someone else's hands. I guess I have to actually set them up and play 'em to see whether the tradeoff works.

Other specs:
* I'll be going headless hopefully with a 1 3/4" nut for wide string spacing, as I was formed as a player during my teens on classical--there were no rock or even jazz teachers in my little town. I really hope Hipshot can accomodate that, as I'd rather not have to individually place and screw in single saddle-tuners like the Meras, one by one. Actually I suspect Hipshot won't accomodate 1 3/4" (I haven't looked it up yet, but I'd bet the farm they don't) so I'm vacillating on this issue as well, not sure what to do.
* Finally, 16" radius, 12-16 if compound. (I'd actually prefer 16-to-20", or just 20" if non-compound--because of my aforementioned classical background, the flatter the better; my non-cover-tunes personal playing style includes almost no bends. But again, Warmoth refuses to oblige).

While he may have overstated a bit about the perceived failings of constant radius necks, he is correct that compound radius fingerboards can generally be adjusted lower at the bridge end. To my mind, a compound radius yields the same effect as a guitar that exhibited endless fallaway as you played up the neck. Most players find it easier to chord on a curved surface, but play single note lines on a flatter surface. It's not a hard and fast rule - just a general one.

I have a client with a number of custom made Taylors. His action is below what I call stupid low. I CANNOT play his guitars without making them buzz. Yet he plays effortlessly with nary a buzz. His touch is that light. And yet a large gnat could not pass between the strings and the frets on his guitars. I can't remember if I posted pictures once of coins being held in place by his strings. I'll do a search and try to post a link...

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"Act your age, not your shoe size" - Prince

Found it in a thread about Earvana nuts. Scroll down to see the story and link to the pix...

viewtopic.php?f=10137&t=52354&p=689967&hilit=fretless+wonder#p689967

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"Act your age, not your shoe size" - Prince

I don’t know about what goes on in a factory, but my limited experience is this:
If you use a radiused sanding beam, (as you might in radiusing the unfretted fingerboard), you initially have a consistent radius along the neck. As the drawing suggests, this doesn’t allow for a straight/level path for a string that is not parallel to the center line of the fingerboard. But once you install the frets and level them with a flat sanding beam moving it along the path of each string (and not just parallel to the center line), you correct this problem—and this may be what he means by “competent fretwork.” I’m not sure about the geometry, but this process may result in a compound radius.


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If I can add one thing to my previous comment:
When you level with a flat beam along the path of the string, you take off more material toward the middle of the fretboard, and less at either end. (This again matches with the drawing.) What this means is that the radius could stay the same at either end of the fretboard, but be decreased near the middle of the fretboard. This makes sense to me, and I believe the geometry works. But this is not what happens in what we normally refer to as a compound radius, where rather than "lowering" the frets at the middle, we are "raising" them at the end of the fingerboard toward the bridge--if that makes any sense.

Didn't read your entire post because I could not wait to start the smack down....

Seriously a compound radius is superior for the lowest possible action and a very desirable thing for most playing styles on steel strings.

We do lots of fret work and teach it too and all that we do is always a compound radius. Besides low action some people struggle with tighter radius boards as in Fender.... and moving to a compound radius can go a long way in helping these folks fall back in love with their Strats and Teles.

Viktor is correct that using long beams flattened and checked on calibrated surface plates and tracing the string paths does result in a compound radius.

It's a process, it's involved, we teach it when we have time and it's desirable. In the acoustic world low action is not as desirable as in the electric and shredder world so the value of a compound radius board on an acoustic is not as great as say on an Ibanez Gem for a heavy metal vomit music player.

PS: Didn't look at any of your links so my comments are general statements.

Aha! Got it, at last. What was puzzling me about those drawings was that the book author says "the strings lie on diverging paths from one another" but then his illustrations show only a single string which looks like it's dynamically changing position. WTH? Very confusing. But after mulling over your comment for a minute and putting it together with his, I finally realized what the missing piece of the puzzle was: the difference between the closer string spacing at the nut and the wider spacing at the bridge.

Instead of having 3 different drawings of a single string, the book should have had one bigger drawing (taking up the same amound of page space) showing three or four strings starting at a recognizable nut and fanning out from each other on an exaggerated diagonal from each other. If he had done that, I would have gotten the point immediately.

So Viktor, thanks for helping clarifying that, and both you and Hesh for confirmation that compound radii are better for action.

Chris--I took a look at those pix. Dude, you are the true spook. I've played a few very low-action guitars so I know they do exist but have never owned any despite having possessed some really high-priced instruments in the past. To see that penny under the E gave me goosebumps as I imagined those strings under my own fingers. Oooooooooooh!

What you say in that thread about light players being finger guys exactly describes me. As I noted above, I cut my teeth on classical. When I began playing rock, obviously I never needed to bother practicing double-stops etc as I already had much better chops than that, but I did use a pick on my electrics because I didn't think I had a choice. I was very intimidated by the much more compact string spacing. (As I note above, there was nobody around to give me any actual rock lessons, so aside from asking for advice from the town's local garage-band guitarist, who was only about 4 years older than me, I was figuring this all out on my own with an occasional Guitar Player issue from the local JC library.) But a few years later I found out that the guy in Dire Straits just used his fingers. I reasoned that if a song as overdriven as "Money For Nothing" could be done fingerstyle on an electric, anything could, so at that point I tossed the pick and haven't used plectra for anything since.

Hey Hesh, c'mon, don't be so vague and noncommittal! We wanna know what you REALLY think!

Once I figured out what was meant by compound radius I thought it was an overly confusing and complex description. At the time I learned it, I realized I was doing it anyway when leveling my fretboard with a straight narrow beam along the string paths. I have not made electric guitars but I suspect it is a bigger deal on a 9.5" or 7.25 " radius fret boards than the 16",20" or 24" that I work with. I previously have heard Chris's described purpose for a compound radius "Most players find it easier to chord on a curved surface, but play single note lines on a flatter surface." But at the time wondered if that was the origin purpose or whether it was to level the string path. Are the end radiuses describing a conic section based on the radius at the nut, the string spread and the spread at the saddle or the preferences for a radiused and flatter section for the player.

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http://www.Harvestmoonguitars.com

I think you are exactly right John. It likely originated out of having straight string paths over a tapered board. I mean, violins have been doing this forever (the more pronounced radius makes it more important). Having more radius for chording and less for single note lines is probably a happy byproduct that was included and advertised. I don't know much about electric guitars but I see reference to a radius at the nut and another number at the other end. I wonder if those two numbers actually define the section of a cone that would be proscribed by following the taper of the board. Perhaps, in the electric world they have altered the numbers to maximize the benefit of having more and less curve for different types of playing.

I put a compound radius on my steel string boards using a hand plane. I plane the board following the imaginary string paths until I have achieved the 16" radius I want at the nut. I don't measure the other end, whatever it comes out to is what it is. As long as my plane strokes were flat, it should work out.

As mentioned, leveling the frets along the string paths has the same effect. It seems surprising to me that there is enough fret material to change a constant radius board to compound radius fret tops, but there is. I mostly do the step of putting the compound radius on the board itself because I want to minimize the time I spend grinding the fret tops. Since I hammer my frets, I don't have to worry about the ever changing radius and what caul to press with.

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Bryan Bear PMoMC

Take care of your feet, and your feet will take care of you.

Okay. Compound radii.

1. It allows bending to occur without fret buzz more easily than with a flat fret board. Bonus. Think about whether or not, in any position on the neck, if you bend, will it cause the string to raise or lower relative to the next fret higher?

It will turn out that if you bend notes from both E's inward....every single time you ask that question...the answer will be "always higher the more I bend inward towards the middle".

2. It allows a curvature many players seems to desire. My only point there is to live and let live. It's a choice...although I will suggest that many guitars do not have compound necks because it facilitates a particular style of playing.

The MAIN point...

3. If you have a guitar with a specific fretboard taper and a specific radius at the nut....you have only ONE mathematically perfect solution for that compound that will result in the lowest action possible.

So...it's in the production of the thing where the math and the product diverge. It's QUITE difficult to follow through, by hand or tooling, a design of a compound fretboard. Perfect executions are few and far between.

THIS guitar was produced in manner to allow the cnc to determine how accurate the playing surface would be. I did kiss cuts on this surface to the point where there was 0 deflection and perfect, stress free flatness. It's FLAT...not a tiny bit of stress. Just carbon - which itself is utterly stiff, flat, and stress free.

So ya...stress. You don't want residual stress in the neck prior to stringing it. Obviating the need for a truss rod is step one. I used massive carbon inside this neck to stabilize it prior to cutting the fretboard surface.

Ultimately...this guitar is was the precursor to further experiments implementing the cnc as the PRIMARY determiner of quality playing action. You START mathematically pure if you have any idea what you are doing with cad/cam/cnc. The only thing you really need to do is HOLD the part securely...and KNOW it isn't defecting as you cut it.

The compound radius is no more difficult to achieve for the cnc than a flat fretboard. The machine doesn't care...it just cuts what you tell it to cut...accurately.

The real art to the compound radius is understanding that each string will now have it's own perfect track from nut to saddle and you'll have to level each string path knowing that. By hand....that's tough. Takes a developed skill. EASY to wreck the perfect mathematical solution.

But...when you DO hold to that perfect solution in building, you end up with the lowest possible playing action.

All I really do is experiment. The cnc machines greatly facilitate the production of any idea. I can tell you this. Between my flat fretboarded model (pictured) and the compound radius on the following model....I made two models and produced many multiples of those designs and they were ALL the best guitars I'd ever played.

The lesson is....without using any cnc's...stress reduction and production control. Make the removal of stress prior to stringing your ultimate goal...and develop your skills such that you can actually produce the solution. For instance...control your fret slots so they don't each spread their slots, causing back bow in the whole neck. That's just one factor in many that will destroy the math purity you need to maintain.

Without cad you'll need to do the math to obtain the radius required at the bridge. You can get that easy to use formula from the Gretch website and many others. This set of videos is particularly useful if don't have a clear
picture of it. https://www.youtube.com/watch?v=8i0MKObjY_s

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I read Emerson on the can. A foolish consistency is the hobgoblin of little minds...true...but a consistent reading of Emerson has its uses nevertheless.

StuMusic

Thanks for all the comments, John & Stuart. Yet further clarification. (nice job on that ax Stuart).

Brian, totally with you on putting it on the fretboard in the first place instead of grinding more material off the frets than necessary.

Good point! I usually think about it like "What kind of ice cream do I want today?", but It makes sense that there would be optimum geometry for certain parameters.

I wonder if anyone has made one of those handy online calculators for this or if there are rough estimates for common guitar neck dimensions...

Pat

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Pat

I'm not a player. I have made a guitar with a 12" rad fretboard, and another with a compound radius, I think it is 9 at the nut, and 16 at the bridge. I made the compound one first, so it seems normal to me. The 12" is nice in some ways because I gave it wider string spacing. I think that it is all about feel. Some could probably play anything, any scale length, fan frets. Doesn't matter. Others get very specific.

Either one can be set up just knowing what you want to put on. do some geometry, and find out how much it will drop at the side, and you know what it is. If you want the edge the same height top to bottom, the fretboard has to have some wedge; unless you make it a compound radius, and then it can be flat. You'd have to figure that out.

Violin fingerboards are a single radius. Some don't believe it. Some don't make them single. But they should be. They look conical because the have a big taper width wise, and the radius is so small, 43mm. So they have a big wedge on them, and the sides are even end to end.

A violin maker in Chicago would say that if you took an oatmeal tube, and cut a wedge out of it, you get the shape, it is a curve, not a cone.

NO matter what kind you have, from flat, to curve to cone; they all need a flat path from nut to saddle, with some relief in the middle. Or not.

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Why be normal?

"...in constant-radius fretboards it is necessary to keep the action relatively high: to avoid buzzes, especially in the outer strings."

I will add that the underlying assumption here is that you're bending notes. I have classical guitars with flat fretboards (constant radius of infinity?) and they can be setup just as low without any fret buzz. Even with a 9" radius, if you're not bending notes you can setup action very low. Heck, all the vintage fenders and gibsons were this way and I have yet to hear anybody complaining about fret buzz on a '59 LP. I actually owned a '59 junior and it was one of the easiest playing guitars I ever played, bending notes and all on a 12" radius. I don't recall hearing Jeff Beck struggle to bend notes on his 7.25" vintage necks.

I'm an avid player and tech, and have been compound radiusing my boards for many years. Huge fan. I heavily prefer the feel of a 7.25" radius on the first part of the neck, and anywhere from 12" to 16" on the end.

Keeping in mind that the board is one thing, and the frets another. Leveling along the string paths seems to be the best way to do it to maintain the compound radius established by planing the board.

I'm a big fan of super low action (3/64" on the treble side or even 2.5/64", 4/64" or even slightly less on the bass side, measured open at the 12th fret) with no to minimal (.002") neck relief. I also am a big fan of huge bends and vibrato, and do them a lot.

The lower action you want, and the bigger bends you want to do, the more critical fretwork is. And the compound radius absolutely helps there. I've done many, many fret levels that are "mock" compound radii, by leveling only the middle of the frets from the 12th fret to the end.

The worst was a Strat with .062" tall frets. And I'll tell you, good thing they were that tall. I literally had to get the frets down to about .042" in the middle, from 12 to the end, to get the high E and B strings to stop choking out on bends. And I mean choking out, like you'd bend and the note would just vanish. Very likely there was a ski jump in that neck, but even on necks without ski jumps, the "mock" compound radius makes an absolutely huge difference.

I do most of my fret leveling under string tension using an i-beam. So I'll just keep leveling until I can bend those strings and they sound clear as a bell. That's probably the most direct education in how a compound radius can help. All you're doing is removing fret material that the strings would otherwise crash into upon bending.

Action matters. I'd be curious how low one could go on a 7.25" board and not choke out when bending on the high E and B strings. I'd be highly skeptical it would be possible to get the crazy low action I like, with the super big bends, without buzzing. Even on boards I've compounded 7.25 to 12", I can end up having to take a lot more out of the middle of the frets to get them where I want.

Of course, if you're not careful, you run into the issue of the 7.25" section being lower on the edges. I actually recently got the Stewmac Guitar Repair Guide to check out the alleged compound radius section where they demonstrate how to calculate the proper compound radius for a given neck. I've always just used small radius blocks in succession, but always ended up doing more fret leveling than I would have liked to.

FWIW, the last neck I did 7.25" to 12" and refretted with .110" x .057" SS frets came out amazing. Feels phenomenal. Now on acoustics where bending is not common, and higher action is standard, I've never understood why 7.25" wasn't a standard. I re-radiused my 12 string to a straight 7.25" and it is so much easier to play bar chords on it's ridiculous. Only thing is I play slide on it ala Leo Kottke and had to re-radius my Acoustaglide brass slide to a 7.25" radius so it would work.

Anyway, I'm getting off topic! But there's so much to discuss with this. Easiest solution for me has always been -- is it choking out on Bends on the High E and B strings? Get my i-beam and level under string tension -- take material only out of the middle of the upper frets -- until the problem goes away. Has worked very well for me for years. Being able to do a compound radius off the bat on the actual fretboard is an even better start here.