Break Angle

[fibrebundle]

Hi,
What is a 'good' range of string break angle over the saddle of a flattop wooden acoustic guitar?
Any help is appreciated!
Thanks.

[honeyboy]

The wonderful Fret's website is a repository of lots of this type of information..

Exhaustive discussion of saddle geometry and break angle here

Here is an 'ideal break angle'


And a bridge about to rip itself from the top of the instrument


If your string break angle looks like this, then you potentially have a problem..


And (as a rule of thumb), small changes in neck pitch can radically affect the string break angle.

On my flattop guitar, a change of one degree (1°) in neck pitch changes the bridge height by .210" and the string break angle by 4°

16° seems to be a happy medium - too much less and you get sub optimal volume/projection, too much more and the forces quickly multiply making the soundboard heavily stressed, more prone to failure and unable to 'sing'..

[fibrebundle]

Thanks. The reason I asked was that I was a little taken back by Bryan Kimsey's comment
(elsewhere, on the Unofficial Martin Forum) that he tries to go for a break angle of about 45 degrees! Isn't this WAY OFF the 16 degree figure you mention?

[honeyboy]

You CAN have a break angle of 45°..

As to whether it makes sense to do so, look at the evidence from the very top luthiers, where they apply their years of experience to build the best that can be built...

The two of the best flattop builders in the world at the moment (in terms of tone and craftmanship) are probably George Lowden and James Olson.

What break angle do they use?


Jim Olson


George Lowden

[fibrebundle]

Jan 14, 2010 10:17:33 GMT honeyboy said:

..................What break angle do they use?

I don't know. What is it??? The pictures don't tell me much.

[honeyboy]

George Lowden uses a break angle usually in the range 16° - 24° degrees, depending upon the design of the instrument, the type of wood and the bracing used on the top.

James Olson uses a 'compound' break angle over his bridges, 16° - 34° where the bass strings are more sharply broken over the bass end of the saddle, "to give a better bass response for a given body size".

His tops are even braced, whereas George Lowden uses a differential "dolphin bracing" that makes one side of the soundboard noticeably more 'flexible' than the other - (they both achieve the same objective but by different means).

Martin Guitars recommend a *minimum* break angle of 20° in their dealer instructions for the fitment of an undersaddle piezo pickup

See this link (PDF)

They suggest 'ramping' the bridge where the break angle is *less* than this..

Looking around, many Martin users seem to prefer a 40° break angle, and ramp their bridges to achieve this.. (Scroll halfway down the page to reach the ramping section)

An adequate test, according to Frank Ford (www.frets.com), is that the break angle should be such that, when the string is under tension, it can't be lifted clear of the saddle.

He is of the opinion that increasing the string break angle follows the law of 'diminishing returns' and can have unintended physical consequences (over time). I think with Frank's expertise and experience with flattop guitars, he does know what he is talking about..

[fibrebundle]

Thanks, Honeyboy! This was quite illuminating. The break angle on my new Martin D-15 is about 27 deg, and it sounds great. So, I guess everything is fine.