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PostPosted: Sun Nov 24, 2019 2:57 pm 
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Koa
Koa

Joined: Fri Feb 10, 2017 11:09 pm
Posts: 585
Location: Cowichan Valley, BC, Canada
First name: Conor
Last Name: Searl
City: Duncan
State: British Columbia
Zip/Postal Code: V9L 2E5
Country: Canada
Status: Semi-pro
A couple questions about break angle and how it relates to the bridge,

First, for my own clarity's sake, when we talk about break angle at the bridge, we're talking about the interaction between the bridge/saddle and the two anchor points of the string (the nut, and however the string is fixed behind the bridge.) Is this correct? In other words, is the break angle as much as it relates to the bridge of a guitar the combination of both angles on either side of the bridge, or is it just the angle the strings hit the bridge from behind?

Secondly, I was wondering if anyone had any documentation to point to, that articulates specifically how different break angles affect the way a guitar plays and sounds, especially in how the string is anchored behind the bridge. I've had lots pf great recommendations for online calculators that have to do with fret positioning, string tension, scale length, and intonation, etc. and was wondering if there was something similar for the way a string breaks over the bridge.

My question stems from two places, first I'd like to bring a more informed perspective to shimming neck pockets. As it stands, my approach is very intuitive, and I don't mind that, but I'd like to cut out some of the guess work. Second from a design perspective, as I'm imagining and drawing things out it would be nice to have some definitive data to draw from. I realize scale length is an awfully big part of this conversation, but I feel like I've got a pretty good handle on the differences between a 24.75", 25", and 25.5" scale instruments, but for instance if I'm wanting to design a guitar that incorporates a bigsby, I recognize a steeper angle is beneficial, but is there a way to decide what the minimum angle should be, and is there a way to decide what too steep might be?


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PostPosted: Sun Nov 24, 2019 4:44 pm 
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Brazilian Rosewood
Brazilian Rosewood
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Joined: Sat May 22, 2010 10:32 am
Posts: 2533
First name: alan
Last Name: stassforth
City: Santa Rosa
State: ca
Zip/Postal Code: 95404
Country: usa
Focus: Build
Status: Amateur
Interesting subject.
The break angle is the angle at the bridge or nut,
where the string angles down.
Most, if not all of the electric bridges are what they are with no adjustment for that.
I don't think it is all that important, but I'm sure some do.
Only time I had a problem was with a flat top I made with a tailpiece that I made as well.
Acoustically the guitar sounded really good.
Only problem was the saddle pickup I put in didn't work well,
because there wasn't enough pressure pushing down on it.
So, I would say steeper is safer,
too steep might be hard on the strings.
Fender took care of the shallow break angle by putting hold down trees on the peg head.
My 2 cents, not worth worrying about.
Alan



These users thanked the author alan stassforth for the post: Conor_Searl (Sun Nov 24, 2019 10:07 pm)
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PostPosted: Sun Nov 24, 2019 8:29 pm 
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Koa
Koa

Joined: Thu Nov 04, 2010 1:46 pm
Posts: 1707
First name: Freeman
Last Name: Keller
Focus: Build
Status: Amateur
Conor, my understanding of the definition of break angle is that it is the angle that the string breaks down as it passes over the saddle. In this picture the angle is 11.6 degrees

Attachment:
IMG_4547-3.jpg


It affects different guitars in different fashions. For an archtop it sets the vertical component of the strings driving force and tension. You can calculate that as two times the string tension times the sine of the angle.

As you start moving the string anchor point from the tail onto the top the angle starts getting steeper and you introduce some rotational components. I have a great vector diagram of the forces on top of a guitar - unfortunately its a gif and forum software won't allow gifs. However as you approach an acoustics pinned bridge you have some pretty large rotational forces - after all thats what makes them work

Attachment:
TORQUE-LOAD-300x160.jpg


But you are asking about electric guitars and the effects on sound. I can't answer that but there is certainly an easy experiment that YOU could do. Take a guitar like a Lester with a stop bar tailpiece

Attachment:
IMG_4930.JPG


Start with the strings wrapped over the top like my picture and crank the stop bar all the way up so there is no angle. There will be no pressure holding strings on the saddles - it will sound terrible. Now start cranking the bar down and do your analysis. You will be increasing the vertical component on the saddles and you will be introducing some rotational components. This (may) bring body and mechanical materials into play - might impact the holy grail of sustain - I don't know. At some point you can switch to thru the bar stringing and take it all the way to the deck.

Fwiw, when I was taking those photos I was also wondering exactly what the break angle at the head of a Gibson (16 degree head angle) and Fender (slab head with string tees).

Attachment:
IMG_4929.JPG


Attachment:
IMG_4931.JPG


Surprised?


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These users thanked the author Freeman for the post: Conor_Searl (Sun Nov 24, 2019 10:07 pm)
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