does a through bridge cause more torque?

So, I've been thinking about bridge/saddles.

With a through bridge the break angle over the saddle is steeper.
On the one hand, the lever arm is shorter. But on the other the twist is greater.

Is it a problem, or a wash?

I ask because I recently bought a uke that I worry will taco at the bridge because it's light, and spruce there, and I'm a little concerned that it might be under built.

If I made it through bridge, i'm not sure if that would be better or worse.

to those who know, does the angle of the string at the saddle or nut make a real difference in sound? it's something i would not worry about. i'm thinking of doing through bridges on my builds. seems to be 6 of one half dozen of the other. having the string knotted in the sound cavity seems to be inherently stronger as you aren't trying to pull a glued block off. again a nit and not critical.

Most of my experience is with guitars, where most have pinned bridges and a few have pinless ones. I've heard many things discussed about the merits of each type but surprisingly I can't remember tone being one of them. I don't think it will make a difference unless you significantly change the weight of the bridge.

spookelele said:

So, I've been thinking about bridge/saddles.

With a through bridge the break angle over the saddle is steeper.

Click to expand...

Incorrect.
Actually, if anything, it's the opposite, ie less steep.
Unless it is built into it, a through bridge has less break angle of the strings over the saddle unless the back of the bridge is tapered (thinned) which it should be to give it more break angle similar to what a tie bridge has.

To adjust the bridge design to get the same break angle, you can/should:
1- Tapered/lower the back of the bridge,
2- Adjust the location that the strings enter the bridge relative to the saddle- closer to the saddle gives more break angle, further away gives less.

With these two things you can dial in the same break angle results, all else being the same (saddle height, action, neck angle etc)

Im not an engineer, but i would say that the torque is very similar between bridges and nothing to worry about- but i would love to hear that officially from an engineer- KEN TIMMS!!!

Hope that helps

chuck in ny said:

...does the angle of the string at the saddle or nut make a real difference in sound?

Click to expand...

Yes, it makes a very big difference to sound.
Very little break angle (more common on older badly made guitars where the neck has tilted and a few other things i wont bother you with) give a weak sound due to no energy being "pushed" into the saddle/top.
Too much break angle and you get a nice bright sound, ...which wont last long as the front of the bridge will likely crack and the top deform after the strings snag and snap from the sharp edge over the saddle.

Beau,

So what is your opinion on multiple hole tie bridges... 2 or 3 holes per string?

I happened upon a ukulele that had a 12 hole bridge and the string was threaded through the lowest center hole then back through the left or right, over to the other hole and cinched in the back. Supposedly it helps with the break angle on tie bridges.

Thanks!

John

70sSanO said:

Beau,

So what is your opinion on multiple hole tie bridges... 2 or 3 holes per string?

Click to expand...

Multi holes are only to secure the string easier/better and by better I mean less possibility of slippage. There is no way that they could effect any other element other then string slippage as the angle of the string isn't effected (ie lowered) in any way with multi hole . Sometimes people use multi holes to tie the string a slightly different way to help the string stay down and not ride up (on classical guitars at least) , but that is kinda slipping hairs in regard to break angle.

This is all, of course, assuming that the lowest hole with a one hole bridge is located at the same height as the lowest hole with a multi hole bridge, which it should be. I put my string hole at the very lowest point i can on my bridges when i do tie bridges.

The one I have is lower than the others. so maybe?



I thought it would be a pain to string but it wasn't that bad.

John

Beau Hannam Ukuleles said:

Yes, it makes a very big difference to sound.
Very little break angle (more common on older badly made guitars where the neck has tilted and a few other things i wont bother you with) give a weak sound due to no energy being "pushed" into the saddle/top.
Too much break angle and you get a nice bright sound, ...which wont last long as the front of the bridge will likely crack and the top deform after the strings snag and snap from the sharp edge over the saddle.

Click to expand...

Beau, how is the tone different?\
Thanks!

Farp said:

Beau, how is the tone different?\
Thanks!

Click to expand...

No power (no break angle)= no tone.

Without energy to drive the top, the get a quiet instrument with no possibility of tone (im talking extreme cases). Ive worked on guitars and ukes where the strings pretty much travel over the saddle in a straight line, with only the slightest dip for a break angle- they all sound like wet cardboard.

Beau, thanks. What if the through holes are closer to the bridge so the angle of the string to and over the saddle are similar to bridges where the string goes through the bridge and is held in place via pins? Does that allow for a break angle so as not to lose potential tone?

Beau Hannam Ukuleles said:

Incorrect.
Actually, if anything, it's the opposite, ie less steep.
Unless it is built into it, a through bridge has less break angle of the strings over the saddle unless the back of the bridge is tapered (thinned) which it should be to give it more break angle similar to what a tie bridge has.

To adjust the bridge design to get the same break angle, you can/should:
1- Tapered/lower the back of the bridge,
2- Adjust the location that the strings enter the bridge relative to the saddle- closer to the saddle gives more break angle, further away gives less.

Click to expand...

Not necessarily incorrect, if you start with the suggestions you stated.

I started with string through bridges, with a tapered bridge, and a very enjoyable break angle. Lots of confidence with the carbon fiber bridge patch regarding pull through (as in, none).

It took me a while to come up with a bridge design that I was happy with that would provide the better than average break angle on a tie bridge. Lo and behold, my 7 1/2 degree back angled saddle contributed to the solution.

Oddly enough, my latest iteration of my bridge looks almost exactly like some guy that moved from AUS to weedtown, except I don't use a roundover for the tie channel. And I didn't even notice, until I looked closely at one of his bridges later when I thought "that looks like my bridge. . . "

Too bad, I'm keeping it. Very functional, especially with my new jig to slot the channels! There.

I should have specified.. if you're using a standard designed bridge.



So, in this image, the black is the basic bridge.
The red being the tie, and the blue being thru.

With the red the break angle is less.
The pivot of the twisting force on the bridge is the saddle.

With a tie bridge the break angle is less, but the lever arm is longer because its from the saddle to the end of the bridge where the string turns around for the tie.

But with a thru bridge the break angle is sharper. The pivot is still the saddle, but now it's pulling more up from the sound board, than as a sheer along the sound board like the tie bridge.

Granted, if you're designing a thru bridge from scratch you can choose the break angle. But if the bridge is already tie because it's completed, and you go to drill thru, its going to be like the image.

On the uke I'm worried about, I can see the stress slightly on the spruce top. Ie, I can see where the braces are on the top by seeing the strain on the surface. On the butt side of the bridge, I can see very slight humps, between where the braces are, and I can see very slight bowls on the neck side of the bridge.

It's very slight.

If I drill the existing bridge in the channel, will that make more or less stress on the soundboard, in a torque sense?

I wasn't going to reply to this thread for two reasons: I don't really care about bridge string break angle and (2) I don't really know about bridge string break angle. Therefore why reply? Well I just got back from the bar (or pub as you Brits might say) and I cant resist.

Thinking back to my old guitar days, this subject was always a big chestnut: Thru bridge or tie bridge? As I remember, the thru bridge was deemed better because it put less torque one the bridge and sounded better because it activated the bridge plate or something.... right. I do remember that this interested me almost less then than it does now. However, I'm no engineer, but looking at spookele's diagram, it clearly shows that the tie bridge puts more torque on the bridge, ie. force x distance = more torque (is that right???).

Anyway, I measured the break angles on my ukes and it is basically 45 degrees on a tie bridge and you know what? It works just fine. Sounds just fine. That being said, I am a hard player and picker and I have had lower break angle strings move on me while playing which isn't good. Having to move the string physically back into position on the saddle while playing can be tricky. Usually a sign I was over playing but annoying nonetheless.

As I remember this whole thing was a wash with the thru bridge people winning by a nose. Personally I got other problems than thinking of bridge string break angles. But is it important? Yeah, maybe really it might be.

spookelele said:

I should have specified.. if you're using a standard designed bridge.

View attachment 86116

Click to expand...

With my tie bridges, the string enters/ is tied through at the very BOTTOM of the trench, so in regard to your picture, the break angels are very similar- in fact- they would be exactly the same if you put the holes for through bridge at the rare of the trench.

SOOOoooooooo..... its all the same in regard to break angle and torque - its just the look thats different.

Beau Hannam Ukuleles said:

With my tie bridges, the string enters/ is tied through at the very BOTTOM of the trench, so in regard to your picture, the break angels are very similar- in fact- they would be exactly the same if you put the holes for through bridge at the rare of the trench.

SOOOoooooooo..... its all the same in regard to break angle and torque - its just the look thats different.

Click to expand...

If the break angle is similar, then, is there still a noticeable difference in tonal qualities? if so, how could a build with a through bridge be adjusted to maintain a tone similar to the tie bridge?

Thanks again...I need to finish my bridge and had planned on a through bridge, lol. If there's a big difference, I still have time to change it.

Farp said:

If the break angle is similar, then, is there still a noticeable difference in tonal qualities? if so, how could a build with a through bridge be adjusted to maintain a tone similar to the tie bridge?

Click to expand...

NO!- there is no difference in tone or torque if the break angles are the same on either bridge style.

Design your bridge to have the same break angle- ie what i have already described
1- by moving the holes where the string enters the bridge forward or back.
2- tapering the back of the bridge

spooky, that picture looks wrong. the red string should go in through the bottom [in the trough]first.that gives a much steeper angle, and depending on the location of the string through hole, could be identical angles. The only advantage I can see for string through is less likelehood of the bridge tearing off, which if properly glued shouldn't happen anyway. The only bridge type I dislike is the slotted type.

makes me want to exactly copy a tie bridge and be happy with that. there's too much i don't know about the subject. most situations call for as little creativity as possible. that's something that should be understood by a crowd of intensely creative people.

strumsilly said:

spooky, that picture looks wrong. the red string should go in through the bottom [in the trough]first

Click to expand...

But that's not really what happens because the knot pulls the string up.