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What reference you use to make sure bridge stands perfectly 90 degree angle


ViolinAnanda

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1. Soon I will be carving bridge and I am curious how one can be sure that bridge back is 90 degree with the top plate so the strings length will be in range 325-328mm. I saw luthiers on videos who only used their eyes looking from side to make sure its 90 degree but im not sure they will be always precise this way. The top plate is often curved so its hard to be sure its 90 degree with that reference. Do they compare it with the edges of violin maybe as reference?

2. In my violin that I bought in dealer shop where bridge was carved by luthier it seems that the back is not 90 degree but the front is 90 degree instead, the string length is 325mm. Is this correct way of carving? I saw other violins in the shop had similar their bridges carved in the same way. I attach photo of my violin and its bridge.

 

 

20240409_231312.jpg

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1 hour ago, ViolinAnanda said:

1. Soon I will be carving bridge and I am curious how one can be sure that bridge back is 90 degree with the top plate so the strings length will be in range 325-328mm. I saw luthiers on videos who only used their eyes looking from side to make sure its 90 degree but im not sure they will be always precise this way. The top plate is often curved so its hard to be sure its 90 degree with that reference. Do they compare it with the edges of violin maybe as reference?

2. In my violin that I bought in dealer shop where bridge was carved by luthier it seems that the back is not 90 degree but the front is 90 degree instead, the string length is 325mm. Is this correct way of carving? I saw other violins in the shop had similar their bridges carved in the same way. I attach photo of my violin and its bridge.

Your photo is distorted from the wide-angle lens, but it seems your bridge is tilted too much toward the fingerboard.

To establish bridge verticality, I look at the gluing plane of the ribs up to the upper corners, and the lines of the tips of the ribs. In my violins, these two lines are at 90° to each other, so both can help the eye in evaluating the verticality of the bridge. I keep the back part of the bridge practically vertical, although actually slightly slanted towards the fingerboard compared to an ideal vertical line. However, the front part of the bridge facing the fingerboard is decidedly more slanted towards the tailpiece. I usually send my customers this photo to help them visualize the correct bridge position in my violins.

Correctbridgeposition.thumb.jpg.1964cb90ed3cfcc69455d24f4b4c1341.jpg

 

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To show customers, I put a business card on the c-bout edge and line it up against the tailpiece side top edge of the bridge so the the bridge is hidden behind the card. About 1/4 of the thickness of the feet should then be showing out at the bottom. The back of the bridge is square to the top, but not quite square to the edges (funny geometry) But not 90 to the edge.... that's too far back for me.

This shows the idea on a funky rental violin bridge . . .  

bridgebevels.jpg

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2 hours ago, Michael Darnton said:

...I put a business card on the c-bout edge and line it up against the tailpiece side top edge of the bridge so the...bridge is hidden behind the card....

I don't understand.  If the bridge is hidden behind the card, how can you tell if it is at the correct angle?

 

2 hours ago, Michael Darnton said:

...This shows the idea on a funky rental violin bridge . . .  

bridgebevels.jpg

I don't understand.  Since there's no business card in this picture, how does it "show the idea" of using a card?

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From a mechanical engineering perspective, you want the net string force transmitted through the feet of the bridge to avoid an unstable tilting geometry and to minimize bending forces that can warp the bridge.

From a player's perspective, you want a bridge shape that will not distract the player.

Michael Darton's photo illustrates the essential setup needed from a mechanical engineering perspective, and a nice bridge shape that should be visually acceptable to most players that are not suffering from mental impairments due to reading too much woo woo theory on the internet.

With a "standard" 4/4 violinsetup,  the net downward force of the strings into the bridge has a very slight tilt from straight down by about 1 degree or so. That gives you plenty of margin for error in bridge setup if you do not stray too far afield.

A "small" taper towards the fingerboard or a "small" taper towards the tailpiece or a "small" taper towards both are all acceptable from an structural perspective.

Within the constraints of a stable bridge position, how much of a taper is a different discussion and enters the realm of sound production.

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I lean the bridge back towards the tailpiece to divide the string angle in half. But to answer the op’s question, I made a block of wood that sets on the top of the violin behind the bridge. Then I push the back of the bridge up against the front face of the block. (I believe that the angle back is 1 degree from 90.) 

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21 hours ago, Brad Dorsey said:

I use the end of a six inch steel rule, on the tai piece side of the bridge.

Now, I tried it and It doesn't entirely contact the surface as top plate is curved but more or less it gives good glimpse if one of corners of ruler is 1-2 mm above top plate. I think it would be a good idea to just make one's own ruler from some stiff plastic material so one of the corners would be 1-2 mm longer and use it as adjusted 90 degree template for given violin.

21 hours ago, Davide Sora said:

Your photo is distorted from the wide-angle lens, but it seems your bridge is tilted too much toward the fingerboard.

To establish bridge verticality, I look at the gluing plane of the ribs up to the upper corners, and the lines of the tips of the ribs. In my violins, these two lines are at 90° to each other, so both can help the eye in evaluating the verticality of the bridge. I keep the back part of the bridge practically vertical, although actually slightly slanted towards the fingerboard compared to an ideal vertical line. However, the front part of the bridge facing the fingerboard is decidedly more slanted towards the tailpiece. I usually send my customers this photo to help them visualize the correct bridge position in my violins.

Correctbridgeposition.thumb.jpg.1964cb90ed3cfcc69455d24f4b4c1341.jpg

 

It seems in your violin top plate is all ideally parallel and perperdicular to the edges so it would make sense. In mine violin there are slight deviations, so can't use this as perfect reference. What string length do you get in your violins after bridge set up? Do you consistenly achieve the same string length (let's say 326.5 mm) using eyes only for 90 degree angle or there is some error margin of 1 mm depending on luck?

Now since my bridge is tilted towards fingerboard, I'm thinking it could be also the cause for my wolftone on A string when I play with bow close to the bridge, which dissapears if I play with bow close to the fingerboard. If I had that additional 1.5 mm of strings length it would give me additional space to play closer to the bridge and maybe the wolftone would be totally gone too.

Also recently watched Edgar Russ's video from Cremona in which he said that the bridge should stand on 1/3 of the line created by the f-holes, not exactly in the center. I always thought it should stand exactly in the center of the line. Is that practice true and what would be the reason 1/3 would be better that 1/2? He says it in this video 

 

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5 hours ago, Brad Dorsey said:

Here’s how I check the bridge angle with a steel rule.  But, going by what some of you are saying, perhaps my bridges lean a little too far towards the tail piece.

 

IMG_0454.thumb.jpeg.2adcbeea53708bd13bbffda5c7c95d99.jpeg

I lean the bridge back about 1 degree, following advice from a violin maker, and other examples. The idea is to split the angle. 

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1 hour ago, ViolinAnanda said:

Now, I tried it and It doesn't entirely contact the surface as top plate is curved but more or less it gives good glimpse if one of corners of ruler is 1-2 mm above top plate. I think it would be a good idea to just make one's own ruler from some stiff plastic material so one of the corners would be 1-2 mm longer and use it as adjusted 90 degree template for given violin.

It seems in your violin top plate is all ideally parallel and perperdicular to the edges so it would make sense. In mine violin there are slight deviations, so can't use this as perfect reference. What string length do you get in your violins after bridge set up? Do you consistenly achieve the same string length (let's say 326.5 mm) using eyes only for 90 degree angle or there is some error margin of 1 mm depending on luck?

Now since my bridge is tilted towards fingerboard, I'm thinking it could be also the cause for my wolftone on A string when I play with bow close to the bridge, which dissapears if I play with bow close to the fingerboard. If I had that additional 1.5 mm of strings length it would give me additional space to play closer to the bridge and maybe the wolftone would be totally gone too.

Also recently watched Edgar Russ's video from Cremona in which he said that the bridge should stand on 1/3 of the line created by the f-holes, not exactly in the center. I always thought it should stand exactly in the center of the line. Is that practice true and what would be the reason 1/3 would be better that 1/2? He says it in this video 

For the reason that the upper surface of the top plate can be curved, I prefer to keep the rib gluing plane as a reference. Sometimes the surface of the top might be parallel to the plane of the ribs, in which case it would be the same thing. This matter of using external aids (ruler, credit card, or similar) is something that can help those who don't have a trained eye, but visualizing the verticality by eye is the best system, because it allows you to mediate between all the various geometric aspects, more or less distorted by time, or more or less correctly aligned during the construction.

As for string length, I usually use 328/329 mm as standard. If I want to modify it I use tricks during the construction of each violin, so that I end up with the correct bridge position and the vibrating string I want. The only space for variation that I can conceive of in a finished violin is 1 mm more or less, which can be obtained by centering the bridge on the line of the notches, or by placing it at 1/3 as Russ indicates. Normally I set it at 1/3 because ideally, I try to keep the top part of the bridge aligned with the line of the notches.

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I check the verticality of my bridges (violin, viola and cello) in front of my music stand by

1-matching the horizotality of the instrument with the stand shelf  with instrument top and

2-the verticality of the bridge with the centerline of the music on the stand.

My preferred bridge on one of my violins was installed by the maker when he sold it to us in 1952 and  is still perfectly straight.

Another violin (1970) still has the maker-installed bridge that was on it when I bought it in 1975. It still passes muster every time a luthier sees it.

 

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22 minutes ago, Davide Sora said:

For the reason that the upper surface of the top plate can be curved, I prefer to keep the rib gluing plane as a reference. Sometimes the surface of the top might be parallel to the plane of the ribs, in which case it would be the same thing. This matter of using external aids (ruler, credit card, or similar) is something that can help those who don't have a trained eye, but visualizing the verticality by eye is the best system, because it allows you to mediate between all the various geometric aspects, more or less distorted by time, or more or less correctly aligned during the construction.

As for string length, I usually use 328/329 mm as standard. If I want to modify it I use tricks during the construction of each violin, so that I end up with the correct bridge position and the vibrating string I want. The only space for variation that I can conceive of in a finished violin is 1 mm more or less, which can be obtained by centering the bridge on the line of the notches, or by placing it at 1/3 as Russ indicates. Normally I set it at 1/3 because ideally, I try to keep the top part of the bridge aligned with the line of the notches.

When you are fitting the feet to the top, do you not use a jig to insure that the bridge placement is repeatable?

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30 minutes ago, FiddleMkr said:

When you are fitting the feet to the top, do you not use a jig to insure that the bridge placement is repeatable?

I don't use any jigs. I simply make two dots on the top, in order to always put the bridge back in the same position quickly, and I take care of the verticality by eye.

 

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33 minutes ago, FiddleMkr said:

When you are fitting the feet to the top, do you not use a jig to insure that the bridge placement is repeatable?

It's not really necessary, but if a jig helps then it's ok to use one. The sanding jigs, and sand fitting bridges in general don't do a particularly good job however. 

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23 hours ago, Davide Sora said:

As for string length, I usually use 328/329 mm as standard. If I want to modify it I use tricks during the construction of each violin, so that I end up with the correct bridge position and the vibrating string I want. The only space for variation that I can conceive of in a finished violin is 1 mm more or less, which can be obtained by centering the bridge on the line of the notches, or by placing it at 1/3 as Russ indicates. Normally I set it at 1/3 because ideally, I try to keep the top part of the bridge aligned with the line of the notches.

Wow, the strings in your violin are long, I think it would help a lot my violin if it had 3-4 mm more string length, but not sure if it would be ok to move bridge further past the recommended notches lime. So I get the idea that it's 1/3 because the upper part of bridge has to be on the center of notches line. But in your bridges the back is slightly slanted, I wonder if that position would be different for bridges with perfect vertical back, as then top part is in different position.

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47 minutes ago, ViolinAnanda said:

But in your bridges the back is slightly slanted, I wonder if that position would be different for bridges with perfect vertical back, as then top part is in different position.

Yes, the angle of the bridge will alter the vibrating string length.

47 minutes ago, ViolinAnanda said:

not sure if it would be ok to move bridge further past the recommended notches lime.

There is nothing sacred about placing a bridge exactly at the notches. Ideal positioning of a bridge can involve many different factors and measurements.
 

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23 hours ago, JacksonMaberry said:

It's not really necessary, but if a jig helps then it's ok to use one. The sanding jigs, and sand fitting bridges in general don't do a particularly good job however. 

The plastic sanding jigs with a big roller at the back make a lovely wagon rut on a soundboard. Apart from just being ridiculous. 

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