Compound Radius Vs. Straight neck

[Jumble Jumble]

I'm well aware of the shim that comes with the Floyd to make it a 10" radius, but that doesn't make the bridge itself a 10" radius. It's a 12" radius bridge with no shims installed.

I guess the reason I don't comprehend the "math", is because it seems to me that by that logic, if  the string radius graduated, then a straight-radius neck would have inconsistent string height as you move up the fretboard, since the curvature doesn't change from the 1st fret to the last. The set-up procedure is no different for a straight than a compound. Only the specs are different.

With a straight radius, if I set my bridge saddle height to 12" (okay, 11" if the nut is 10" and the bridge is 12"), the string height is still consistent from the 1st to the last fret. Yes, the action gets higher as you move up, but the curvature remains consistent. If I bolt on a compound radius neck, the strings don't magically know that they're supposed to "fan out" as you get closer to the bridge. The only thing that changed was the fretboard radius. Sure, I adjust the bridge saddles to have consistent string height at the 12th fret, but that doesn't change what's happening at the 22nd. If it did, then the string height at the 22nd fret on a 12" radius neck would be flatter than 12 inches and would not be a good thing.

Adjusting bridge saddle height for a compound radius neck is always gonna be a compromise, with the ideal setting at the 12th fret in most cases.

Just because I flattened out my bridge saddle height for the compound radius neck, that doesn't seem to change the fact that the 12th fret is around a 12" (13"?) radius just as it would be on a straight 12" radius neck. the fretboard just got flatter from there on.

There's a big difference between going from 10" at the 1st fret to 12" at the last, and 10" at the first fret to 16" at the last.

Going from 10" to 12" (11" at the 12th, as someone stated) is not gonna be very noticeable.

The Floyd comes with the shim installed - like this, it matches the nut radius. So in effect, yes, technically the bridge is a 12" radius, but when you buy one, leave it stock and don't alter or dismantle it, it's 10". This is probably why some people call it 10" and some call it 12". Everyone on here refers to it as 12", and the knowledge about the shim and what it does is a bit hard to come by. So when I had to shim mine from 12 to 18.34, I found that shim, and I left it in. Since then I've taken it out and it's better.

Don't put math in quotes like that's not what it is. It's not that you don't comprehend the "math", it's that you don't comprehend the math. A 10" nut and a 10" bridge over a 10" fingerboard - how would that be a problem? Clearly the string radius would stay at 10" along its length.

The thing I've marked in bold - well that's just wrong, or in fact, it looks to me like it contradicts itself. In it you appear to say that you'd set the nut at 10" and the bridge at 12", and you acknowledge that at the 12th fret that would make the radius of the strings 11". But then you say the curvature remains consistent. Well, which is it? Does it go from 10 - 11 - 12, or does it stay the same?

Reading this makes me wonder: on a compound radius neck, do you just set the string height by getting the 12th fret right, and not with radius gauges etc? (That's how I do it on bridges with individual height adjustment).

If you do, then maybe it feels to you like you're setting the radius of the bridge to be equal to whatever the radius is at the 12th fret, but you're not. Your bridge saddles will be on a flatter radius than the strings are at the 12th fret.

Imagine you have a fixed 10" radius nut, and a fixed 10" radius bridge (say a Floyd with the stock shim left in). So the strings will follow a 10" radius for their entire length. Now, on a 10 to 16 compound neck, obviously the strings will be more curved than the fretboard by the time you get above the 12th fret. So let's say we set the bridge radius to 16" instead. Now at the 12th fret we're halfway between 10" and 16" - so, 13". The string radius continues to increase as they get closer to the heel, but when we get to the 22nd fret, the fretboard has hit 16", but the strings still have a way to go before they get there.

To get to the point where the strings have reached 16" by the 22nd fret, the same as the fretboard has, we need to set them so that by the time they get to the bridge they're even flatter. Of course, with individual string height adjustment this is easy. We just set our string heights above the frets as we normally would, and this "just works". We get 10" at the nut, 16" over the 22nd fret, and... well, who knows? The bridge is just set to whatever worked.

However, for a Floyd or a TOM, we don't have individual adjustment, so we need to know what radius they should be to achieve that 16" radius over the heel of the neck. By being clever and doing the math, we get 18.34". And in fact, if you have, say, a Tele bridge over a 10-16 neck, and it's perfectly set up, then measuring the radius of the strings at the bridge would indeed give you that value.

There's no reason string height over a compound radius neck needs to be a compromise. You can lay a straight edge along the neck, touching every fret (when the neck is perfectly straight). Lift that straight edge slightly and you have the path a string will follow. Simple.

 

[Strat Avenger]

With a compound radius, you want no relief in the neck because you do not NEED relief in the neck because the compound part of the equation takes the place of relief. I refer to my previous post where I explain this.

This is complete and utter B.S.  All necks, including compound radius, need some amount of neck relief (forward bow) for best playability with minimal fret buzz.

 

[Strat Avenger]

I'm well aware of the shim that comes with the Floyd to make it a 10" radius, but that doesn't make the bridge itself a 10" radius. It's a 12" radius bridge with no shims installed.

I guess the reason I don't comprehend the "math", is because it seems to me that by that logic, if  the string radius graduated, then a straight-radius neck would have inconsistent string height as you move up the fretboard, since the curvature doesn't change from the 1st fret to the last. The set-up procedure is no different for a straight than a compound. Only the specs are different.

With a straight radius, if I set my bridge saddle height to 12" (okay, 11" if the nut is 10" and the bridge is 12"), the string height is still consistent from the 1st to the last fret. Yes, the action gets higher as you move up, but the curvature remains consistent. If I bolt on a compound radius neck, the strings don't magically know that they're supposed to "fan out" as you get closer to the bridge. The only thing that changed was the fretboard radius. Sure, I adjust the bridge saddles to have consistent string height at the 12th fret, but that doesn't change what's happening at the 22nd. If it did, then the string height at the 22nd fret on a 12" radius neck would be flatter than 12 inches and would not be a good thing.

Adjusting bridge saddle height for a compound radius neck is always gonna be a compromise, with the ideal setting at the 12th fret in most cases.

Just because I flattened out my bridge saddle height for the compound radius neck, that doesn't seem to change the fact that the 12th fret is around a 12" (13"?) radius just as it would be on a straight 12" radius neck. the fretboard just got flatter from there on.

There's a big difference between going from 10" at the 1st fret to 12" at the last, and 10" at the first fret to 16" at the last.

Going from 10" to 12" (11" at the 12th, as someone stated) is not gonna be very noticeable.

The Floyd comes with the shim installed - like this, it matches the nut radius. So in effect, yes, technically the bridge is a 12" radius, but when you buy one, leave it stock and don't alter or dismantle it, it's 10". This is probably why some people call it 10" and some call it 12". Everyone on here refers to it as 12", and the knowledge about the shim and what it does is a bit hard to come by. So when I had to shim mine from 12 to 18.34, I found that shim, and I left it in. Since then I've taken it out and it's better.

Don't put math in quotes like that's not what it is. It's not that you don't comprehend the "math", it's that you don't comprehend the math. A 10" nut and a 10" bridge over a 10" fingerboard - how would that be a problem? Clearly the string radius would stay at 10" along its length.

The thing I've marked in bold - well that's just wrong, or in fact, it looks to me like it contradicts itself. In it you appear to say that you'd set the nut at 10" and the bridge at 12", and you acknowledge that at the 12th fret that would make the radius of the strings 11". But then you say the curvature remains consistent. Well, which is it? Does it go from 10 - 11 - 12, or does it stay the same?

Reading this makes me wonder: on a compound radius neck, do you just set the string height by getting the 12th fret right, and not with radius gauges etc? (That's how I do it on bridges with individual height adjustment).

If you do, then maybe it feels to you like you're setting the radius of the bridge to be equal to whatever the radius is at the 12th fret, but you're not. Your bridge saddles will be on a flatter radius than the strings are at the 12th fret.

Imagine you have a fixed 10" radius nut, and a fixed 10" radius bridge (say a Floyd with the stock shim left in). So the strings will follow a 10" radius for their entire length. Now, on a 10 to 16 compound neck, obviously the strings will be more curved than the fretboard by the time you get above the 12th fret. So let's say we set the bridge radius to 16" instead. Now at the 12th fret we're halfway between 10" and 16" - so, 13". The string radius continues to increase as they get closer to the heel, but when we get to the 22nd fret, the fretboard has hit 16", but the strings still have a way to go before they get there.

To get to the point where the strings have reached 16" by the 22nd fret, the same as the fretboard has, we need to set them so that by the time they get to the bridge they're even flatter. Of course, with individual string height adjustment this is easy. We just set our string heights above the frets as we normally would, and this "just works". We get 10" at the nut, 16" over the 22nd fret, and... well, who knows? The bridge is just set to whatever worked.

However, for a Floyd or a TOM, we don't have individual adjustment, so we need to know what radius they should be to achieve that 16" radius over the heel of the neck. By being clever and doing the math, we get 18.34". And in fact, if you have, say, a Tele bridge over a 10-16 neck, and it's perfectly set up, then measuring the radius of the strings at the bridge would indeed give you that value.

There's no reason string height over a compound radius neck needs to be a compromise. You can lay a straight edge along the neck, touching every fret (when the neck is perfectly straight). Lift that straight edge slightly and you have the path a string will follow. Simple.

It wasn't a contradiction, although my choice of wording probably isn't the greatest. I was simply referring to the consistency of string height over all frets. The action may be 1/32" over the 1st fret, 2/32" over the 12th, and 3/32" over the 22nd (I'm just making these numbers up), but the consistency of all 6 strings over the top of each fret is pretty much the same on a straight radius fretboard.

Let's forget about the Floyd for a minute and use a Fender Strat bridge. Each individual saddle is gonna be adjusted for the desired string height over the 12th (or perhaps even the 17th, depending on preference) fret. Yet the curvature of the 1st, 5th, 7th, 15th, 17th, 22nd frets are all gonna be different from the 12th on the compound radius neck. So yeah, you "flattened" out the bridge saddles for the flatter radius, yet the curvature at the 12th was no different than the curvature of a straight 12" neck.

Now back to the Floyd; obviously you reduce the "crown" of the individual saddle heights (by shimming the E,A,B, and E up closer to the D&G), and adjust the overall height of the entire bridge up or down to the desired string height.

I'm not saying you are wrong about anything, but rather that I don't quite understand the math or physics of it. That doesn't make me stupid, and my guitars all play quite well. I've gotten quite good at setting them up, and anything too challenging for me, I have a Pro do for me.

I only own one compound radius neck (on my Soloist), and I had to shim the Floyd. My future builds will not have Floyds on them, so I was just trying to think in terms of a 12" straight radius setup versus a 10"-16" setup using individual saddle adjustments.

 

[Cagey]

I don't think anybody's saying you're stupid. Far from it. If anybody thought that, they wouldn't try to explain how things work, as it would be pointless.

Some people are able to abstract spatial relationships more easily than others, often just from numerical descriptions of geometry. It's been a subject of study in the male/female mental process differentiation for years. Currently, it is thought that males are more suited to such tasks than females, but there's been some subdivision in that area as well. For instance, males seem to be able to mentally rotate objects in space more readily, while females seem to have a greater spatial memory. Lends credence to the idea that women are better at directions than men.

It sounds like you're setting your guitars up based on performance, rather than any measurement. In other words, in the case of bridge radius, you get the bridge height close, then adjust the saddles until you don't have any string buzz anywhere on the board. Nothing wrong with that. Works every time, except in theoretical arguments. But, I'll bet that given a perfect neck, if you set it up as close to perfect as you know how, you'd find that your bridge radius on a 10"-16" compound radius neck equipped guitar would be about 18". You've just either never measured it or had perfect parts.

So, the question is not whether you're stupid, it's: are you a male, female or indiscriminate? <grin>

 

[Dan025]

part of the problem here is that the difference between a 12" radius and a 18" radius is smaller than you would think. a compound playe pretty well with a 12" radius so it's pretty easy to justify the logic that either is a compromise but ya gotta trust that 18-19" is ideal. the warmoth employees have said so in the past. we can go about arguing the math all day but 18" is best though 12 is acceptable.

so i was unaware that a floyd is shimmed to 10" from 12" i never had a licenced floyd, only cheap floyd rose II bridges made from zinc. sounds to me like you can reverse the shim arangement and get closer to 14" or 16" without buying or making shims unless the center 2 sadles share one wide shim.

 

[thearmofbarlow]

This is complete and utter B.S.  All necks, including compound radius, need some amount of neck relief (forward bow) for best playability with minimal fret buzz.

Someone better tell my former employer this. We set them up with dead straight boards. 1.5mm action on both E's. They play just fine. Well, they did when I was there anyway.  :laughing7:

Let's forget about the Floyd for a minute and use a Fender Strat bridge. Each individual saddle is gonna be adjusted for the desired string height over the 12th (or perhaps even the 17th, depending on preference) fret. Yet the curvature of the 1st, 5th, 7th, 15th, 17th, 22nd frets are all gonna be different from the 12th on the compound radius neck. So yeah, you "flattened" out the bridge saddles for the flatter radius, yet the curvature at the 12th was no different than the curvature of a straight 12" neck.

The 12th fret doesn't mean shit. It's only the halfway point. Stop thinking in terms of frets and think in terms of relation between fretboard shape and the path the strings take.

If the radius is 10" at the nut, 16" at the last fret, then the radius has to be higher at the bridge in order for a consistent string height to be maintained across all frets. On a straight radius it has to be the same size at the nut AND the bridge.

Let me provide a visual for you...

This is part of a cone. The top is a 10" radius, the bottom is a 20" radius. From top to bottom is 25.5". This is what a compound radius looks like in its complete form. Now to get complex...

The white bit represents your strings. There are six of them, with a 1.5" spacing at the top and a 2-1/16" spacing at the bottom. This is, of course, on a 10" and 20" radius respectively. If we take this part of the cone, lay it on its side, and even out the heights of the two radii we end up with this...

Where the pink line is a 10" radius and the yellow is a 20" radius. The blue line in the middle of the "strings" will be the radius at the 12th fret. Now let's see what we have if we put all three radii next to each other.

Again the pink line is 10", yellow is 20". The red line represents the 12th fret. Now are you seeing the issue? If you set your bridge radius to match the 12th fret you're not matching the conical shape of the fingerboard. You're not graduating from a 10" to a 20" radius, you're going from a 10" to whatever the 12th fret radius is. As a result your D and G strings will be higher than necessary, and your E's will be lower. Like I've said before, a lot of people don't care. I'm one of 'em. But this is how it is.

 

[stubhead]

...but when they ask us WHY we love this place, all we do is grunt and gesticulate.... :hello2:

 

[Strat Avenger]

It sounds like you're setting your guitars up based on performance, rather than any measurement. In other words, in the case of bridge radius, you get the bridge height close, then adjust the saddles until you don't have any string buzz anywhere on the board.

On the contrary. I set up all my guitars to exact specifications. I don't "eyeball" anything. What I have not done that I obviously need to do, is measure my bridge saddle radius (you got that part right). That would probably answer all my questions.

 

[Strat Avenger]

@ thearmofbarlow,
Thanks for taking the time to illustrate the concept for me.

 

[thearmofbarlow]

@ thearmofbarlow,
Thanks for taking the time to illustrate the concept for me.

No problem. As my girlfriend puts it "people are either geometry or algebra". I'm obviously a geometry guy and I forget a lot of times that it's difficult for other people to visualize random text from a message board. Could have saved twenty minutes of typing with five of modeling. :doh:

Just don't ask me to solve for x. :laughing11:

 

[Jumble Jumble]

@Street - yeah, as Cagey said - we wouldn't be trying to explain it to you if we thought you were stupid. My only frustration in this thread has been at my own inability to successfully explain it.

I'm glad we've cleared it up - you were setting the string radius correctly at the 12th fret and didn't realise the effect this was having on the bridge radius.

And re the geometrists vs algebraists thing. Yeah I'm obviously the latter! I actually developed a spreadsheet a while back where you could type in the radius at the nut and the heel, and it would tell you the radius at each fret and at the bridge. Or you could do it the other way, so for instance if you want a 10" nut and a TOM bridge left stock at 12", it would tell you that you'd need a 10-11.44" (iirc) compound radius neck to achieve that.

I don't have the spreadsheet any more but I could reimplement it in JavaScript and run it up as a webpage somewhere if anyone's interested.

 

[ghostrider]

OK, so without trying to sort through so many pages of back and forth, is there a conclusion on setting up a guitar with a 10-16 neck? I understand all of the geometry but that doesn't tell me how to get a consistent string height. Someone once told me to setup for 18" radius at the bridge. Awesome. That makes logical sense. So how?

Right now, I'm setup for about 6-ish/64ths at the 17th fret to avoid buzz. The action is obviously inconsistent. It feels nice and low on the first 1/3 of the fretboard but starts getting uncomfortably high past that. What steps should I take? I have a vintage style 6-hole bridge.

Thanks in advance.

 

[Nightclub Dwight]

Having been math challenged all my life, I have learned a lot from following this thread.  Thanks to everyone for either explaining and illustrating the concepts or for asking the questions that needed clarification.  ccasion14:

 

[Patrick from Davis]

Pick Guardian has a printable radius gauge, here.  I am sure that it can be handy for anyone that didn't plunck down the cash to get one made of metal from Stew Mac.
Patrick

 

[ghostrider]

Pick Guardian has a printable radius gauge, here.  I am sure that it can be handy for anyone that didn't plunck down the cash to get one made of metal from Stew Mac.
Patrick

Thanks. It turns out I had it really close to this. My low E and G were a bit high. It turns out, if I lower them to match the radius, I get massive amounts of buzz on the E and enough buzz on the G to make me change it back. I don't really want to raise all the other strings so IDK. I'm OK with the low E being a bit more raised and I can understand why that buzzes (thicker string and larger wave height), but I'm not sure why the G buzzes.

 

[Cagey]

If you haven't done it, it probably needs a good neck setup. Even a brand spankin' new neck won't let you adjust the nut and bridge to ideal until the frets are level. All it takes is for one to sit a little proud, and you have to start compromising.

 

[Strat Avenger]

I actually developed a spreadsheet a while back where you could type in the radius at the nut and the heel, and it would tell you the radius at each fret and at the bridge. Or you could do it the other way, so for instance if you want a 10" nut and a TOM bridge left stock at 12", it would tell you that you'd need a 10-11.44" (iirc) compound radius neck to achieve that.

I don't have the spreadsheet any more but I could reimplement it in JavaScript and run it up as a webpage somewhere if anyone's interested.

I'd definitely like to see that...

 

[Updown]

Yep it's all in the maths ....  :icon_biggrin:

Now  .... How long is a piece of string ?    :laughing7:

 

[Cagey]

 

[Super Turbo Deluxe Custom]

"So, I'm a janitor at a college.  I'll see equations on a blackboard, and I'll just finish them in my head...and my best friend is Ben Affleck."