Kerfing the Bridge

[John Cadd]

Kerfing the linings is meant to help the vibrations in the top.How much difference would kerfing the Rosewood bridge make?Keep the bone in one piece if you like.
How many patterns of bridge have been tried to get some extra resonance from the strings?
A violin bridge stands high compared to a guitar bridge.The bow movement is converted to up down movement.A guitar bridge is doing all it can to stop the string vibrating.
How about a sideways (flat ) version .For some reason I keep thinking of a 2CV Citroen suspension system. One crazy idea was to have 3 strings attached one side of the guitar and 3 strings the other side.So normal vibrating strings but split each way below the bridge.
Fantasy guitar time.

[John Cadd]

Here`s another thing that`s been drifting around.A bridge fitted below the top connected through two small holes.Literally working like an upside down bridge.It`s a tricky one.

[William F.Eden]

What have you been into lately John ? ? What ever your dreaming about why don't you give it a try and keep us posted You sound like the guy that wanted me to build a different Guitar for him he had this brite idea of two sepret chambers I told him it would not work but I built it for him anyway and sure enouff it didnot .Good luck Bill.""""""""""'

[Tim Mace]

OK...uncharted territory...as I thought the main function of kerfed lining was for ease of following the contour of the instrument sides although I'm sure it decreases weight compared to solid lining not to mention above all to create
something to glue the top and back to.Not much interested in the kerfed bridge idea but never heard the vibration of the top linked to kerfed lining.Where was this info obtained? John, you must be as bored as I am.

[Ned Knepp]

Hi John,
Interesting ideas.

With the idea of placing the bridge below the face; how do you envision supporting the saddle?

I don't understand what you mean when you said a "sideways (flat) version". I know how a 2CV's suspension works but I can't make the connection with a guitar's bridge/saddle.

Ned

[John Cadd]

Well you know how evrybody worries about volume all the time.Looking at a violin bridge ,you could make one really low and get a really quiet violin.
The narrow waste of a violin bridge is allowing some movement.The height is giving leverage,although that word sounds a bit wrong there.
If you glued a strip of rosewood across a violin that would not be good.
The upside down bridge would be very awkward.It would look like a normal bridge but two connections through the top would work something like a violin bridge inside the guitar. The tension would be pulling the wood instead of pressing on it.Then via the bridge back to the top surface.
Savart did experiments like this with violins.
If it ever went wrong --well I don`t want to think about that. Its all about ways to get some leverage and flexibiity.
The sideways idea would be complicated.It would not produce enough movement in the right directions.
A higher bridge would create a glue problem ,I imagine.

[Frank Ford]

Kerfed linings are NOT designed to improve anything. Linings are there for support to a fragile little gluing surface, one that is often broken by the addition of binding and purfling. In early times, the linings were solid for better appearance, or they consisted of teeny little blocks individually glued in place.

Kerfed lining strips are made that way to expedite installation and cut labor costs - plain and simple. Now that we've had a hundred years or more to look at them, we accept their appearance, and all is right with the world.

Now, as to splitting the bridge, Kasha did that as did/do some of his disciples.

Keeping the bridge solid makes good sense from a structural standpoint, that's for sure. One thing that is too often overlooked by those wanting to "improve" traditional design is in-depth research to see what has been done in the past and how well it fared. A flat top guitar bridge is doing a lot of work besides impeding tone. To make an analogy with a violin bridge might make sense when comparing it to an archtop guitar bridge, but it fails when discussing the flat top guitar bridge, because of the intense "rocking" motion that contributes so much to the tone.

Remember, we pretty much have settled on what range of tone and sustain we like in a flat top guitar, so monkeying around too seriously with design may produce a new sound, but it is unlikely to be of interest to the general population of players.

One of the more colorful instrument designers was Lloyd Loar, who went basically broke with the "Vivi-Tone" guitar. He developed those with a hole in the top and a great tall bridge that went through the hole and connected only to the back of the guitar, which was spruce with f-holes.

[John Cadd]

Yes Frank . The "solid "bridge as it stands helps to sound the overtones.I noticed when trying out tuning methods that muting all but one string being tuned left a very thin uninteresting sound.
Kerfing the linings seems to have a few different reasons depending on who`s explaining it.Personally I don`t know.
Some players tie the strings to avoid the loop just behind the bridge.With the string running direct to the hole for the string there is a tiny change in the string angle which does alter the sound.Tone or volume? not sure.
I settled for a thing to try.Picture a half round dowel glued below the bridge so the string runs through a hole (sorry about that) and attaches inside after rhe string has run through 180 degrees.
This half round dowel would be about one centimetre thick. Details of attachment not sorted.
A simple box with two identical strings fitted in each way will clarify whether it does something or nothing.
When I mentioned leverage maybe I should have said torque.That`s more connected with rotation.

[Ned Knepp]

Hi John,
I think I understand what you mean with your upside down bridge but I still can't see any benefit. Arch top instruments don't have the upward pressure on the bridge that a flat top has but they still vibrate in multiple directions. I agree with Frank that the bridge design we use now has undergone a LOT of development and is pretty good considering the sound we want from our instruments.

Just for the record, I don't think my guitars sound thin and uninteresting when I mute all but one string. I get overtones from the instrument even if there is just one string on the guitar.

I don't understand the point of adding mass to the bridge structure and rerouting the strings through 180 degrees before crossing the saddle. I guess I don't know what you are trying to test/prove with this. It seems to me that you are still going to be pulling upward on the face of the top while increasing the torque of the rolling forces on the bridge. IMO, I don't think this is desirable. The strings will still pull up on the back of the bridge and push down on the front as they cross the saddle. I can't envision any way to avoid this as long as you attach the strings to the bridge assembly. What am I missing?

Ned

[John Cadd]

I shall need to sort out my thoughts before I give you a proper answer.One part of this is the reason to tie the strings without the loop pulling at the string just as it comes over the bridge.Is that done for neatness or for volume or tone?The angle of the string is slightly altered when this is done.
The other part of this idea is thinking about turning a tight object from one side,then gripping right round with the fingers.Vibration is a confusing thing because from a small distance you could say."no ,it`s not moving at all",but it is.
I personally like guitars the way they are.

[Tim Mace]

I don't like guitars the way they are but the hard part has been worked out.I don't have enough time left to reinvent the guitar family.Just reading about it takes up most of my
day.

[Frank Ford]

[quote]How many patterns of bridge have been tried to get some extra resonance from the strings?[/quote]

Before you spend too much time designing things, you should definitely investigate some of the dead limbs on the tree.

For example, check out "Durkee's Patent" bridge. That was a sort of conventional looking bridge with pins, but the strings inserted from the FRONT edge of the bridge, wrapped around the pins and then over the saddle, making a 180 degree turn.

Another one was "Tilton's Improvement" of 1854, which utilized a tailpiece to anchor the strings which passed through holes in the back of the bridge and then over the saddle:

TIlton even got into goofing with top grain orientation.


Here's Gibson's anti-rotation device:

[Ned Knepp]

John,

Remember that I'm an amateur but it seems to me that you are concerned with details that don't really have the impact you think they have. As far as bridge design is concerned my (amateur) experience brings me to understand that the angle of approach and departure on a saddle can change the sonic properties of an instrument but, as far as I can see this is a matter of bridge design and not the method of string anchorage. There are examples of guitars that use pin bridges, pass through bridges, tie bridges and even slot bridges that all appear to work equally well. I think it is possible to mess up the break angle on any of them so, as far as I can see, how the string terminates is a bit of a detail that may not have a lot of bearing on the sonic properties of the guitar so much as it is based in tradition and preference.

I have to admit that I'm partial to the pin bridge because I think it will afford better break angle adjustments if the saddle needs to be lowered but I'm not considering converting my tie bridge ukulele's to pins. I just don't see justification for the added complexity and added weight that would be required. The tie bridges work just fine on the lighter tensioned ukes. I've seen tie block classical guitars but I don't recall ever seeing a steel string with this configuration and I think it is would not be such a good idea to try this. The point is that all of them have good break angles and all use different types of anchorages and I think break angle is more important than how we hold the strings.

I'm afraid that I don't understand the last part about turning a tight object but I think Frank is right that study can save us a lot of trouble. When I repair an instrument, I usually spend a lot more time studying the problem than actually doing the repair. My amateur status allows me to do that and I really need it.

Ned