PDA

View Full Version : does a through bridge cause more torque?



spookelele
12-04-2015, 04:56 AM
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.

chuck in ny
12-04-2015, 05:59 AM
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.

PeterF
12-04-2015, 08:03 AM
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.

Beau Hannam Ukuleles
12-04-2015, 10:14 AM
So, I've been thinking about bridge/saddles.

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

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

Beau Hannam Ukuleles
12-04-2015, 10:21 AM
...does the angle of the string at the saddle or nut make a real difference in sound?

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.

70sSanO
12-04-2015, 11:18 AM
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

Beau Hannam Ukuleles
12-04-2015, 11:41 AM
Beau,

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


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.

70sSanO
12-04-2015, 12:12 PM
The one I have is lower than the others. so maybe?

86109

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

John

Farp
12-04-2015, 12:56 PM
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, how is the tone different?\
Thanks!

Beau Hannam Ukuleles
12-04-2015, 02:30 PM
Beau, how is the tone different?\
Thanks!

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.

Farp
12-04-2015, 04:22 PM
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?

Kekani
12-04-2015, 05:02 PM
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.
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.

spookelele
12-04-2015, 06:09 PM
I should have specified.. if you're using a standard designed bridge.

86116

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?

sequoia
12-04-2015, 08:03 PM
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.

Beau Hannam Ukuleles
12-05-2015, 07:45 AM
I should have specified.. if you're using a standard designed bridge.

86116


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.

Farp
12-05-2015, 08:01 AM
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.

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.

Beau Hannam Ukuleles
12-05-2015, 09:21 AM
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?

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

strumsilly
12-05-2015, 09:42 AM
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.

chuck in ny
12-05-2015, 11:34 AM
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.

spookelele
12-05-2015, 12:33 PM
spooky, that picture looks wrong. the red string should go in through the bottom [in the trough]first

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

86138

Beau Hannam Ukuleles
12-05-2015, 01:19 PM
But that's not really what happens because the knot pulls the string up.

86138

And a multi hole bridge stops this slight lifting up,.... its not really a problem though....i mean, it can be, but it shouldn't be on a well made instrument. ie- It wont make a great uke not great

DennisK
12-05-2015, 03:08 PM
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.
Are you sure you're not confusing break angle with string-height-at-bridge? Those badly made guitars probably had the saddles adjusted as low as possible to try and combat the high action, and the low string height definitely affects the sound.

Yes, below a critical value the break angle will be "too low" and sound like crap, but I'm not convinced that there's any tonal difference between 15 degrees and 45 degrees.

I'm not an engineer, but I'm fairly certain that the torque on the soundboard is 99% determined by the string-height-at-bridge. Pinned bridges will have less stress on the glue joint, but the bridge is so stiff that any forces generated inside the bridge footprint will be carried to its edges unchanged. So regardless of where on the bridge the strings are anchored, and the degree of any angles they break over, the whole bridge acts as a lever, and the height where the strings leave it is all that matters.

Dearman
12-05-2015, 03:23 PM
I am an engineer and the lever arm isn't the big difference. The two methods apply load differently. The tie loads the bridge in bending and shear. That is transferred to the soundboard by the bond line. The shear load is distributed by the area of the bridge, bending is as well but it applies a little different. The bending load reverses (twist means one side is held down, the other pulls up) trying to peel up the bridge.

The pins are different. The shear is now primarily carried by the pin or string on the hole. The combined thickness of the bridge (in the valley) and the soundboard thickness are carrying the load. In my business we might increase the thicknesses, increase pin size or put in a double row of pins if we think we will deform (egg) the hole. The pins, strings and soundboard are basically set so you are left with increasing bridge thickness if the hole wants to egg. You can do this later in repair if needed. Bending is still your second load on the soundboard but it now acts over half the distance (the lever you mentioned) and the upward load clamps the bridge and soundboard rather than lift the bridge against the soundboard. This means you are no longer trying to peel the adhesive. Most adhesives are designed for shear and struggle in peel and most joints are clamped tight to keep a thin bond line to give the best shear performance. Peel prefers thick (to a point) so most carpentry joints try not to load the adhesive this way.

So, you have changed the bending load to some extent but more importantly you have reduced the chance of peeling up the bridge and increased the chance of egging a hole without adequate area (bridge thickness for us). Since egging can be repaired with a thicker bridge, I think it a lesser concern.

There is a lot more than this such as the bending coupling also acts out of plane, the second moment of inertia of your joints, clamping force of the pin joint and the stress riser effect of the transition from the bridge to soundboard but I'll leave it at the high level.

spookelele
12-05-2015, 03:59 PM
Dearman: Can you simplify/clarify for me?

Assuming I don't change the bridge/saddle that's on there, if I drill through to convert to a thru bridge, will it be less apt to taco the sound board?

If I understand you, which I'm not really sure I do, I think that's what you're saying, with the risk being that I could pop the bridge off more readily because it becomes more pull and less shear?

I understand the hole deforming. I think I cold probably off set that by gluing in a small brass tube or maybe the alu bit from a pop rivet.

Dearman
12-05-2015, 04:13 PM
The thru should make popping the bridge off much less likely. Without doing the math, I think the likelihood of taco'ing to be similar or less than.

DennisK
12-05-2015, 04:31 PM
The thru should make popping the bridge off much less likely. Without doing the math, I think the likelihood of taco'ing to be similar or less than.
Please do the math, because that's precisely what's important here :) As I said, pinned bridge = less stress on glue joint. But that doesn't have any effect on tone. What we need to know is whether the string anchor location (within the bridge footprint) and break angle over the saddle have any effect on the torque applied to the soundboard. My intuitive brain says no, provided that the bridge is much stiffer than the soundboard.

sequoia
12-05-2015, 05:22 PM
Please do the math, because that's precisely what's important here :) As I said, pinned bridge = less stress on glue joint. But that doesn't have any effect on tone.

Thank you Dennis. I was sure we could stir one of you engineer types out of your log tables long enough to give us an intelligent reply and your reply earlier was perfect. I'm not sure I understood it in totality, but it sure sounded good. I think the original poster asked the simple question of whether break angle would effect tone. The answer is an emphatic no if I read you correctly. The second question was whether torgue would be different (and possibly deleterious) with the two different types of tie offs and the answer is definitely yes... Phew. Glad we got that settled.

By the way, I do believe this question goes back to the 15th century (I'm no historian) when lute makers started to angle the peghead at radical degrees to increase the break angle at the nut on the theory that a higher break angle gave a purer tone. Like 60 degrees or more. Also I think they thought it looked cool and they probably sold more lutes. It took a hundred or so years for lutiers to figure out that that acute break angle wasn't needed and plus it was structurally weak so they decreased the angle to what we know now and guess what? The tone didn't change. However sales went flat (!).

So do what Beau does and everything is gonna sound fine.

strumsilly
12-05-2015, 05:35 PM
But that's not really what happens because the knot pulls the string up.
slightly, but not much. Bottom line, they all work and have advantages and disadvantages. String through seems to me most secure, unless you have a pickup, then it becomes fiddlier. Both of my main players, Loprinzi and Koaloha have pickups and tie bridges. I did a survey and the clear winner was the tie bridge. http://forum.ukuleleunderground.com/showthread.php?98676-bridge-preference&highlight=bridge+survey

Dearman
12-05-2015, 06:16 PM
Please do the math...

I'll take a look with a couple of colleagues and post what we come up with in a few days. I'm curious how the height affects things.

Beau Hannam Ukuleles
12-06-2015, 09:06 AM
Are you sure you're not confusing break angle with string-height-at-bridge? Those badly made guitars probably had the saddles adjusted as low as possible to try and combat the high action, and the low string height definitely affects the sound.

I'm not confusing break angle with string-height-at-bridge. Incorrect string-height-at-bridge (from incorrect neck angle) will lead to incorrect break angle.


Yes, below a critical value the break angle will be "too low" and sound like crap, but I'm not convinced that there's any tonal difference between 15 degrees and 45 degrees.

There is a tonal difference between extremely low break angle and extremely steep break angle. This tonal difference becomes less the closer those two extremes are. So there will be tonal difference between a 2 degree break angle and a 89 degree break angle. Less so if it's 15 and 45.


I'm not an engineer, but I'm fairly certain that the torque on the soundboard is 99% determined by the string-height-at-bridge. Pinned bridges will have less stress on the glue joint, but the bridge is so stiff that any forces generated inside the bridge footprint will be carried to its edges unchanged. So regardless of where on the bridge the strings are anchored, and the degree of any angles they break over, the whole bridge acts as a lever, and the height where the strings leave it is all that matters.

Yes. String height at bridge is the main element for top deformation due to torque (top rotating/twisting) but a high break angle over the saddle will contribute to more torque and a low angle will cause the strings to push down (like an archtop or violin) with less rotation of the top.

Lastly, The discussion of glue sheer strength and stresses on tie vs through bridges is redundant when you consider a classical guitar.
A tenor uke has 35-45lbs of string tension.
A classical guitar has 90-100Lb of string tension on it. DOUBLE that of the tenor uke. Both ukes and classical guitars have a tie bridge.

SOooooooooooo if a classical guitar can survive 100lb of string tension with a tie bridge then certainly a uke can with only 40lb thus making the discussion of torque in relation to bridge and glue failure and sheer strength obsolete.
Tie bridges do have a bit more pull on the very back on the bridge, but classical guitars show us that this just isn't a problem, assuming some obvious things:
1- The bridge is well constructed/stable (not floppy)
2- Appropriate bridge plate and top braces.
3- Bridge is glued on correctly.

PS- A lifting bridge every 10 years isn't a badly designed bridge. It's just a naturally occurring element of wooden instruments with glued parts and string tension.

Timbuck
12-06-2015, 09:38 AM
Yup Beau ! All good stuff ....keep the bridge / saddle low..fretboard thin or don't have a fretboard at all like the Island ukes...shorten the scale...use lighter strings ... and all these things will reduce the torque on the bridge.
Please let me know if I'm wrong cos I've been on the bottle tonight ;). Cheers :cheers:

DennisK
12-06-2015, 01:58 PM
I'm not confusing break angle with string-height-at-bridge. Incorrect string-height-at-bridge (from incorrect neck angle) will lead to incorrect break angle.
Yes, they do change together as you sand down the saddle (and the mass changes too). But you can design the bridge to change one or the other independently, to sort out what is actually degrading the tone. With a 12 or 18 hole tie block bridge, you can try two different break angles depending on how you tie it. Alan Carruth has done some experiments with that. Here's a great thread with discussion of all this stuff http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=38743&p=509065


Yes. String height at bridge is the main element for top deformation due to torque (top rotating/twisting) but a high break angle over the saddle will contribute to more torque and a low angle will cause the strings to push down (like an archtop or violin) with less rotation of the top.
Reading Alan's post on the second page of that thread, it sounds like I may be wrong about this, and the break angle actually does affect the torque. Or at least the effective location that the torque is applied to the soundboard. But at the same time, the difference is mostly inaudible, whereas you can hear a difference in the string height.

Hopefully Dearman's math will help clarify this further. I'm still not convinced that zero break angle will produce a purely downward force when the strings are anchored within the bridge footprint. Maybe it would if the soundboard had zero stiffness, but as it is, pressing down on the soundboard causes it to push back, and feed back into an upward force behind the bridge, which wouldn't happen with an actual tailpiece bridge.

Read Trevor Gore's posts in that thread too. Interesting discussion of how low break angle allows the string to roll side to side on the saddle, whereas high break angle prevents that.

Here's another Alan Carruth post, where he mentions that break angle doesn't matter much for acoustic tone, but does for UST pickups. http://www.luthiersforum.com/forum/viewtopic.php?p=562115#p562115
But you can angle the saddle slot backward a few degrees to get more pressure on the pickup without changing the break angle.

Beau Hannam Ukuleles
12-06-2015, 04:15 PM
With both high or low break angle there IS top rotation, however less break angle there is less rotation and noticeable tonal loss in extreme cases. I dont think tieing strings slightly (12/18 holes) differently would change tonal response enough to fuss with it, assuming that the the holes were close to each other, ie- only changing the angle 1, perhaps 2 degrees.

i totally agree with Alan when he says (on that forum link) "The bottom line was that it was easy to hear, and measure, a difference when the string height off the top was changed, but break angle doesn't seem to matter [in regard to tone] unless you don't have enough."

The part where he says "unless th don't have enough" is a bit redundant as if you dont have enough break angle, simply tieing the strings a slightly different way with an 18 hole bridge (on a guitar) or 12 hole on a uke to gain a degree or two will not fix the sinking ship...however every bit helps!!

Also, what Alan said about string height is cause enough to use fingerboards thicker then traditional thickness. I use a 5mm thick FB on my ukes which I find nice.

Kekani
12-06-2015, 04:27 PM
Here's another Alan Carruth post, where he mentions that break angle doesn't matter much for acoustic tone, but does for UST pickups. http://www.luthiersforum.com/forum/viewtopic.php?p=562115#p562115
But you can angle the saddle slot backward a few degrees to get more pressure on the pickup without changing the break angle.
As noted in post #12 of this thread. However, changing action at the bridge will still change & affect the break angle over the saddle. What changing action will NOT relatively affect is intonation with a back angled saddle, which is nice.

In the end, this is splitting hairs for a few degrees that no one will hear, and can (and will) be affected even more by any string change the player makes. In fact, IMHO, turning a tie bridge into a string through with a bridge plate that is not necessarily designed for it may not be the best idea.

Do I pay attention to break angle? Of course I do. On my Tiples, I intentionally set it low on a pin bridge. 4 stringers? As steep as I can on a tie bridge. I did an 8 hole bridge on a tie style 4 string specifically to gain the greatest break angle over the saddle. Worked very well. However, so would a "normal" tie bridge as I've only done since. Okay, maybe not "very well". The owner didn't know how to string it up and jacked up the space between the two holes; but that's another story.

Beau Hannam Ukuleles
12-06-2015, 04:36 PM
What changing action will NOT relatively affect is intonation with a back angled saddle, which is nice.

How can intonation NOT be affected by changing the action on a back angled saddle??- this i dont understand?????? (i didn't re read #12 though so i might be missing something)

Kekani
12-06-2015, 05:25 PM
Beau, you would enjoy post #12, the last part. . . you'll know why. . .

Here's the part about the back angled saddle.

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.

By angling the saddle slot so that it is not 90 degrees perpendicular to the top, but rather 82.5 degrees (which I do with ALL my instruments, whether they have a pickup or not - of course most that do have LRBaggs), if you raise the action, the scale length increases. Vice versa, lowering action decreases scale length. If intonation is set from the beginning, you can raise or lower action at will. . .

DennisK
12-06-2015, 07:18 PM
With both high or low break angle there IS top rotation, however less break angle there is less rotation and noticeable tonal loss in extreme cases. I dont think tieing strings slightly (12/18 holes) differently would change tonal response enough to fuss with it, assuming that the the holes were close to each other, ie- only changing the angle 1, perhaps 2 degrees.
From the post on the second page of that thread I linked before (http://www.luthiersforum.com/forum/viewtopic.php?p=509280#p509280), changing the tie method changed the break angle from 6 degrees to 25 degrees. So 6 degrees is "enough", and more isn't necessarily better.

So getting back to this,


...does the angle of the string at the saddle or nut make a real difference in sound?
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.
My point is, break angle only makes a big difference in sound right at the boundary between non-functioningly low and "enough". Above that, it doesn't make much difference in sound.

And secondly, continuing to raise the string height does make a big difference in sound, and will distort the top, as you say. But the increasing break angle is only incidental to that, and not the cause of the sound change or the distortion change. You could pull the bridge off and replace it with another that raises the string height without changing the break angle, and those changes would still happen.

It's an important distinction when designing new instruments.

thomas
12-07-2015, 04:36 PM
i first heard about the back slanted saddle from rick turner before he was chased off this forum. i adopted it too. i miss rick's contributions. enough so that i quit coming here for a long time after he left.

i have done string through bridges since the first instrument i built following hana lima's book. the method has treated me well. on terz and parlor guitars as well.

i think bridge and especially bridge patch design play a very important role in the instrument. often overlooked.

take care,
thomas

Beau Hannam Ukuleles
12-08-2015, 04:22 AM
Beau, you would enjoy post #12, the last part. . . you'll know why. . .

hahhahha- weedtown.
Before i left australia, i pre made about 100 bridges on a milling machine with that trench thing for the ties but now im in the US i dont have access to a milling machine so I will probably be changing my bridge design soon...unless i buy a nice XY table.
The trench might become more like 4 drilled creators, or i'll do a through bridge as they are way easier to make.

Aaron- Did you say you had trouble with through bridges and carbon fiber bridge patches???

Kekani
12-08-2015, 04:38 AM
hahhahha- weedtown.
Before i left australia, i pre made about 100 bridges on a milling machine with that trench thing for the ties but now im in the US i dont have access to a milling machine so I will probably be changing my bridge design soon...unless i buy a nice XY table.
The trench might become more like 4 drilled creators, or i'll do a through bridge as they are way easier to make.

Aaron- Did you say you had trouble with through bridges and carbon fiber bridge patches???
You need to see my new bridge slotting jig. I use a Dewalt compact router with a plunge base; takes care of the angled slot with a small insert that raises the back of the bridge from underneath, and the flat trench without the insert to keep the bridge flat. I did a class on this at the UGH Exibition this year. Not sure if the concept was too much, but some guys took pics.

For neck through, I love the concept, and no issues for me, save for longevity. The issues are for the players and string changes, and losing beads, etc. The panacea for me was the carbon fiber patch, which I have a LOT of long term confidence in, and now I have a bunch of really nice CF material after making a hybrid canoe paddle for my son.

Beau Hannam Ukuleles
12-08-2015, 05:02 AM
You need to see my new bridge slotting jig.

Yes. Yes I do !!!- I need to make something like this for my saddle slots at the very least.

thats good to know that the CF patch also works with through bridges.

Kekani
12-08-2015, 01:25 PM
Yes. Yes I do !!!- I need to make something like this for my saddle slots at the very least.

thats good to know that the CF patch also works with through bridges.
O use it on my pin bridges too, specifically, Tiples.

thomas
12-08-2015, 04:17 PM
Kekani,
Did you have problems in the past with string through bridges and wooden bridge patches?

Kekani
12-08-2015, 04:46 PM
Kekani,
Did you have problems in the past with string through bridges and wooden bridge patches?
Nope.

Then again, all of my string through have CF over the patch.

thomas
12-09-2015, 02:15 AM
Thanks for the info.

Right when I started making instruments Aaron Keim told me about Pete's method of starting with a nice wooden bridge patch and feathering it to paper thin at the edges. I adopted that and have used string through bridges on it and havent heard of any problems. even on guitars. My oldest instruments are only about 6 years old though.

I have always been leery of putting anything synthetic inside the box. I guess I am a tone freak like that.

Take care,
Thomas

Kekani
12-09-2015, 04:41 AM
Thanks for the info.

Right when I started making instruments Aaron Keim told me about Pete's method of starting with a nice wooden bridge patch and feathering it to paper thin at the edges. I adopted that and have used string through bridges on it and havent heard of any problems. even on guitars. My oldest instruments are only about 6 years old though.

I have always been leery of putting anything synthetic inside the box. I guess I am a tone freak like that.

Take care,
Thomas
David Hurd.

Beau Hannam Ukuleles
12-09-2015, 04:44 AM
I would use a ferret as a bridge patch if i thought it would help tone and stability.

Don't let 'traditional' materials limit your building.

Andyk
12-09-2015, 04:54 AM
I would use a ferret as a bridge patch if i thought it would help tone and stability.

http://craftyweasels.com/wp-content/uploads/2013/02/replacement.jpg

:)

thomas
12-09-2015, 07:33 AM
What weight of carbon fiber is commonly used?

spookelele
12-09-2015, 09:16 AM
I'll take a look with a couple of colleagues and post what we come up with in a few days. I'm curious how the height affects things.

Any math?

I'm less interested in height because although it does cause torque over sheer, I'm stuck because the height is linked to the fretboard height and I can't change it.

But I could change to a thru from the tie without drastically changing anything if it will actually be less stress.