Cutting a Bridge?? Options

[BarryD]

Is there any GOOD information available that explains the concept and specifics of cutting a bridge? How much to cut from the crotch, how much to open up the heart, kidneys etc.

[Michael Darnton]

Though it doesn't have any numbers on it, here's what I generally do, more or less. If you go to the http://violinbridges.co.uk site you can see what good shops through time have done. Notice that there's a certain consistency to it, if you track the most famous ones.

As for what to do to change various things, the biggest problem I have in communicating that is the lack of a proper vocabulary--I listen to the violin, and from experience I sort of know where to go, but I couldn't always tell you why.

[Oded Kishony]

What this lovely picture fails to reveal is the fact that a bridge is a THREE dimensional object and that the third dimension is critical to how it functions.
Ther is an arch to the front and back of a bridge. This arch is crucial to the overall design. Maybe you can convince Michael to show a picture showing the arch (aka belly) of this bridge.

Oded Kishony

[Mike_Danielson]

The first order of fitting is to get the bridge to fit well at the feet, followed by the string height adjustment. Once you have this done, you can follow the general dimensions as given in Stroebel's book, but a very good reference is what is reported on the violinbridges website--this website does offer a lot of variation in the dimensions, however, and that is a confusion.

I think the most important diemension (once you have done the above) is the width at the waist, and usual dimensions for this are in the range of 16.0 to 15.0 mm. The height and waist-width are major controllers of the bridge resonance frequency. In an uncut bridge, this frequency can be above 4000 hz; you want it to be around 2900 hz, but that value is also dependent upon whether you want a solo instrument or not (raise it for a solo instrument). This is something that you can hear because droppping the resonance frequency removes a harshness on the A and E-strings.

The lower the bridge height, the more that must be removed from the waist-width to get the resonance in the right range.

If you can get to the old CAS journals, look up the articles by Jansson (5/99 issure, for instance), but the most recent on bridge resonance is in the VSA journal (Summer 2005) in an article by Curtin.

[Michael Darnton]

Of course the most interesting thing to come of those articles is that the bridges cut by the major firms usually fall within the tuning parameters. . . without having been actively tuned . . . which is why it's important to look at the pictures to see what those shops were doing.

[Jeffrey Holmes]

I agree with Michael concerning the tuning issue....

There are a good number of past threads about bridge style, cut, material, etc. A search should turn up some interesting reading. Where's Guy (falstaff) when you need him???

[Jeffrey Holmes]

Here's an old thread that deals with bridge profiles and a few other things (warning; long!):

Bridge profile thread

[gabi]

Hi Michael,


Do you always cut the protector patch with 135 degrees angles or sometimes you make it round like Jeffrey's ?


thanks,Gabriel

[fiddler59]

Michael,
I remember you mentioned in a previous thread you were going to publish a bridge "how to primer" (for lack of a better term) on your web site. Is that still a posibility, I hope so !!!

Bridgely challenged,
David Blackmon

[Michael Darnton]

I have written it, but not shot the photos to go with it.

[Michael Darnton]

quote:

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Originally posted by: gabi
Do you always cut the protector patch with 135 degrees angles or sometimes you make it round like Jeffrey's

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Yes, I always do mine that way--I cut mine from a sheet of skin; I suspect his are precut.

[Jeffrey Holmes]

quote:

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Originally posted by: Michael Darnton

Yes, I always do mine that way--I cut mine from a sheet of skin; I suspect his are precut.

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I used to do the same as Michael (I cut them from a drumskin), but I admit... if I'm not going to the trouble of an ivory inlay (rare), I really love the precuts... A small luxury. They are available in a few different thicknesses... but I like the thin ones for violin.

[GMM22]

For what it is worth, I am learning to leave bridges stiffer these days. Reducing the resonance too much often kills the bass and sometimes releases a strident or harsh A and E that is hard to tame. My new theory is that it is better to err on the side of a more stout bridge than to make one too weak.

Could there possibly be schools of bridge cutting? By this I mean certain methods that yield consistant results with a characteristic sound that is not better or worse than any other, but yet different.

Here is an analogy:

As far as arching and thicknessing goes, there are several main appoaches such as Guarneri, Stradivari, Amati, etc. We all know that no one approach is universally accepted as superior, but rather each has merits and represents a model that gives a certain characteristic sound. Could it be that the technique of bridge cutting falls into this type of realm?

I have begun to notice that many violins I set up end up sounding similar even though the violin models are very disimilar, as if a type of sound emerges from the very approach that I use.

[GMM22]

Ivory inlay? What is that? And what advantage (if any) does it offer?

[Michael Darnton]

I try to tune the bridge to the customer, rather than to the violin. :-)

[GMM22]

Assuming this is a new customer (as previous cumulative experience would certainly govern existing relationships) how do you ascertain what the customer wants?

[Michael Darnton]

I have a nice discussion about what they have now, and how they'd like to see it change. That's the very first thing I do with any customer, anyway, before I adjust anything, or make a move on their instrument. Then I'll play their violin and ask about things I notice--sometimes I don't like something, but the player does. After I get a map in my mind of where things are, and where the player wants them to be, I start. I don't do much work without seeing the player (that is, stuff sent to me), and I don't usually feel comfortable with doing that: my taste may be completely different from theirs, so it's dangerous to do things based on my opinions.

[Jeffrey Holmes]

quote:

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Originally posted by: GMM22
Ivory inlay? What is that? And what advantage (if any) does it offer?

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It's a small sliver of ivory inserted into a slot in the top of the bridge under the e string before the bridge is finished. It serves to prevent the e string from cutting into the bridge (like the parchment, but it doesn't show on the front or back side of the bridge). Some players like them (they think they're classy looking). They are very effective. If a player uses a really hard e string, they can be a pain at times (the shape has to be maintained, as they sometimes develop a sharp spot and snap strings). I don't notice a difference in sound, really. They're more work.

Here's one. The bridge it's on is a good decade old:



I try to tune the bridge to the player and the instrument. :-) ... but I think I'm taking liberties with Michael's point (which is a good one).

If there is no player yet (the instrument is mine) I try to do what I think will be most effective for the instrument's response.

I certainly notice regonal preferences in bridge appearance/performance... but really, it goes further than the bridge itself. The post (how snug it is and the placement), the set of the neck (in general; height & stand), and even bassbars have some variation by region... but Michael's mention of similarities between better shops/makers is correct. There are similar characteristics in bridges that "work".

[fiddler59]

I think a lot of people would like to know what effect trimming in different areas in the bridge has on sound......example; 1. raising the lower arch next to the belly of the violin, 2.narrowing the waist by trimming the inside of each kidney, 3. raising the inside of each kidney toward the E and G string, 4. trimming the lower arch in the heart of the bridge. I think if someone could shed some light on these
points it would be very helpful.
Sincerely,
David

[Jeffrey Holmes]

quote:

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Originally posted by: fiddler59
I think a lot of people would like to know what effect trimming in different areas in the bridge has on sound......example; 1. raising the lower arch next to the belly of the violin, 2.narrowing the waist by trimming the inside of each kidney, 3. raising the inside of each kidney toward the E and G string, 4. trimming the lower arch in the heart of the bridge. I think if someone could shed some light on these

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The effects these details have on response varies according to wood & profile of the bridge, and the build of the instrument to which the bridge is installed... and just to complicate matters, the effect of the cuts relate to each other. I've had arguments with almost every, if not every, chart that has been produced on the subject... I'm not sure there's really a way to produce more than gross general rules concerning thickness and trim (which I seem to remember were touched on in some previous thread... but can't remember how far back it was), but there are certain details (especially where wood isn't removed) that can be noted on bridges cut by those who know what they're doing. Try that "bridges" site Michael mentioned.