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I made a guitar with 25' top radius (25' top and back to save money on radius dishes) but then the neck angle needed to be rather high as well, resulting in the need for a bridge saddle that are as high as Sears Tower, or giant bridges to compensate. I think 28' isn't that big of a difference from 25' so the question is, do manufacturers who make a top that steep uses a very big bridge as well?

Or is it safe for me to use a top that are completely flat with no radius, or will it be safer for me to use a shallow radius (greater than 40')?

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Cat-gut strings are made from kitten guts, stretched out to near breaking point and then hardened with grue saliva. As a result these give a feeling of Pain and anguish whenever played, and often end up playing themselves backwards as part of satanic rituals.

Typhoon Guitars
http://www.typhoon-guitars.com

?? Not sure I understand.
Neck angle is what sets your saddle height, independant of top radius - if it's too high, your neck angle is wrong.
You could build with a flat top, or with larger radius if you want to.
Some people do either very successfully.

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

What I mean is, the 25' radius forces you to use a very high neck angle, otherwise there would be an ugly gap between the fingerboard extension and the soundboard.

How do I have a low neck angle and a 25' radius?

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Cat-gut strings are made from kitten guts, stretched out to near breaking point and then hardened with grue saliva. As a result these give a feeling of Pain and anguish whenever played, and often end up playing themselves backwards as part of satanic rituals.

Typhoon Guitars
http://www.typhoon-guitars.com

You can sand the top or the bottom of the fretboard to close the gap, no matter what the top radius is. At 25' you won't have to sand much to close the gap. I use 28' and it works out with no sanding most the time.

I'll try that on my demo build, because it already have a 25' top dome. I just see a small gap on a previous build that also has a 25' dome, it's about 1/16" I think but its just enough to make someone think that the guitar was poorly made. I raised the neck angle on that one to close the gap but it ended up making the bridge/saddle height really high.

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Cat-gut strings are made from kitten guts, stretched out to near breaking point and then hardened with grue saliva. As a result these give a feeling of Pain and anguish whenever played, and often end up playing themselves backwards as part of satanic rituals.

Typhoon Guitars
http://www.typhoon-guitars.com

Tai,

A really tall bridge and saddle might cause someone to think your guitar was poorly made as well. Check out tutorials by John Hall, Robbie O'Brian and Hesh. They all have shown ways to acheive proper neck to body geometry.

Steve

It never occurred to me that I could shave the bottom of the fretboard to close the gap, I thought of strange solutions like filling the gap with maple wedge, etc. but I just could not find any literature (even looking over Cumpiano's book) on getting everything to look right as far as neck angle is concerned.

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Cat-gut strings are made from kitten guts, stretched out to near breaking point and then hardened with grue saliva. As a result these give a feeling of Pain and anguish whenever played, and often end up playing themselves backwards as part of satanic rituals.

Typhoon Guitars
http://www.typhoon-guitars.com

I don't use 25 It does set the neck angle at about 2 degrees. If you radius the entire to a 32 will be about a 1 1/2 degree. Also how you locate the disk will change things. This vid may show you how you can control the disk and its inference to the neck angle
http://www.youtube.com/watch?v=LrgRKKsx ... 8CA71FE7D2
I use a 28 dish but don't radius the entire top. Here is another link that a friend of mine uses a 32 and does the entire top.

http://www.midatlanticluthiers.org/Meeting_Photos.php

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John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

I make my guitars with a flat top (no dome) but I tapper the body from the top of the soundhole to the top of the body by 0.75*. Basically this is a drop of 1/16" which sets my neck just how I like it.

The very best thing to do is draw out the guitar from as many angles as you can. You will get a much better idea of how these things work.

Many people use 25' radius dome with great success. BUT it's all about total understanding of the geometry.


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I am here: http://maps.google.com/maps?ll=49.069498,-122.355431

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My Facebook Guitar Page

"There's really no wrong way, as long as the results are what's desired." Charles Fox

"We have to constantly remind ourselves what we're doing....No Luthier is putting a man on the moon!" Harry Fleishman

"Generosity is always different in the eye of the person who didn't receive anything, but who wanted some." Waddy Thomson

Rod hits a great point , draw it out. As he said drawing this will help you visualize it better. Once you can see it and all the lines are drawn you will see how all the geometry relates to each line. That alone will help answer many questions

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John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

When you draw it out, do you draw it to the radius you used for your x-braces, or do you allow for some "spring-back" from the top once the braces are glued to it? Seems like the flat top would counter some of the brace radius, resulting in a final radius that is somewhat larger than what the braces were radiused to. If that's the case, how do you estimate what the final radius will be on the glued up top? Am I overthinking this?

Yes. You really can't account for spring back that you can't calculate. Just draw it out as it "should" be and adjust when building.

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My Facebook Guitar Page

"There's really no wrong way, as long as the results are what's desired." Charles Fox

"We have to constantly remind ourselves what we're doing....No Luthier is putting a man on the moon!" Harry Fleishman

"Generosity is always different in the eye of the person who didn't receive anything, but who wanted some." Waddy Thomson

Whew! Thanks Rod.

You're not looking hard enough...

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Trevor Gore, Luthier. Australian hand made acoustic guitars, classical guitars; custom guitar design and build; guitar design instruction.

http://www.goreguitars.com.au

John - I just watched the top radius video. Lot's of good info there. Thanks for sharing that!

First of all, if you had draw this before, you would have seen the problem on paper instead of on wood.

Second... you have many solution for this (not for this build, but for the next ones)
- raised neck
- avoid spherical radius

I personnaly build with ''compound'' radius. I carved the dome I want on a workboard that have the shape of my guitar. The section where sits the fingerboard is flat, or almost, and the higher point of the dome is under the bridge. Using this method, the ribs stay flat. Works great for me.

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Francis Richer, Montréal
Les Guitares F&M Guitars

I find a 28 ft radius to be perfect .. if you flatten the area where the FB sits, taking off about 4-5 thou will do it, then the FB lies flat there, and shoots back to the bridge area giving about a 1/16 inch gap - perfect fo r a 1/4 inch FB, and a 5/16 to 3/8 bridge and reasonable saddle.

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Tony Karol
www.karol-guitars.com
"let my passion .. fulfill yours"

Tony - when you say you flatten the area where the FB sits, are you referring to flattening the spruce top after it is glued to the ribs, or flattening that portion of the ribs before you glue the top to them?