warped violin bridges

[Al Cramer]

I'm a player who has become somewhat obsessed with carving bridges and noodling around with bridge & soundpost placement. Given my limited but evolving knowledge, I'm really bugged by warped bridges, because they make it hard for me to visualize the force vectors. But I'm curious: you always read  that if a bridge is too warped, it can snap and damage the instrument. Is this really true? Has anyone actually seen that happen? Thanks!

[Mark Norfleet]

Yes.

The damage is usually just cosmetic though, other than needing to replace the bridge.

[The Violin Beautiful]

Yes, it’s true. This happens quite often if people aren’t careful with their instruments. Sometimes if you inspect a warping bridge you’ll find a hairline crack. 
 

The most common spot in a violin bridge for a break is right through the middle, but sometimes the break can be at one of the feet. Cello bridges have taller legs, so there’s more likelihood of a break in that region.If you see enough customers, you get to see all kinds of broken bridges!

[Al Cramer]

Thanks for your replies!

I  am really envious of people who have so much experience working with these amazing instruments. I am only beginning to understand how they work.  You think you've learned something about bridges and soundpost placement, and then find you've done a setup that's impossible to play. Then you start to noodle with with nut heights and fingerboard scoop and struggle to relate that to what you know about bridges and soundposts, and realize that you basically know nothing...somethig very holistic is going on with setup!

I am very grateful for Pegbox and the willingness of people to share their knowledge.

[nathan slobodkin]

21 hours ago, Mark Norfleet said:

Yes.

The damage is usually just cosmetic though, other than needing to replace the bridge.

Unless it startles the player into dropping the instrument!

Very important to tell players to keep bridges straight. I often have instruments come in that I have to straighten the bridge before I dare examine them. 

[Dave Slight]

22 hours ago, nathan slobodkin said:

Very important to tell players to keep bridges straight. I often have instruments come in that I have to straighten the bridge before I dare examine them. 

This happens most days. It is incredible how some players can have the bridge so tilted, yet not even realise. A bit more tuning and the bridge would come down.

Can get very expensive to fix, if the underside of the adjuster cracks the belly.

[uncle duke]

On 1/15/2020 at 8:20 PM, Al Cramer said:

 Given my limited but evolving knowledge, I'm really bugged by warped bridges, because they make it hard for me to visualize the force vectors. 

Put another one on and don't go so thin the next time.  If you cut your own blanks from scratch choose harder maple.

I believe weak violin bridges that warp slow down string performance, hence my reply.

[sospiri]

1 hour ago, Dave Slight said:

This happens most days. It is incredible how some players can have the bridge so tilted, yet not even realise. A bit more tuning and the bridge would come down.

Can get very expensive to fix, if the underside of the adjuster cracks the belly.

Damage from the underslide is a fault in design. It shouldn't happen.

[Dave Slight]

3 hours ago, sospiri said:

Damage from the underslide is a fault in design. It shouldn't happen.

Not really sure what you mean here.
When the bridge tips over, the tailpiece then slams into the belly (on violins and violas). The underside of the adjuster, being the highest point, makes contact first, followed by the string ball ends.

Such a large force in a small area makes some pretty deep depressions, and can lead to a crack, which usually lines up with the sound post.

[Al Cramer]

Dave Slight -- many thanks for the clarification! I didn't understand your first post, but now I get it. I can definitely see how the tail piece slamming down (especially the fine tuner of the E) can cause serious damage.

[Tom Fid]

On 1/16/2020 at 8:36 PM, Al Cramer said:

I am very grateful for Pegbox and the willingness of people to share their knowledge.

Amen to that!

[baroquecello]

Warped bridges really Damage the Sound. They basically work like springs or shock Absorbers on a car, the opposite of what you want. (well almost the opposite; the violin Bridge design has evolved into what it is now in order to filter out certain unwanted frequencies, so it is a selective shock Absorber, if you wish) Sometimes it is possible to straighten them, but then extra care has to be taken in order for them not to become crooked again. And as a new violin Bridge is not so expensive and not so much work (compared to Cello bridges, which are my reference Point) I usually get them replaced.

[TimDasler]

I've seen some bridges warp astonishingly far and stay standing, but they can also snap from warping. If you ever have a junk bridge try snapping it in your fingers. Once they're carved they're easier to snap than you might think.

Since you mention an interest in the forces at play, consider the angle of the string over the bridge. The centerline of that break angle should go directly through the bridge and stay within the bridge where the feet meet the top. If the bridge leans back the line of force falls behind the bridge and it will want to warp backwards. On violins it is more frequent that they lean forward as they are tuned and that line of force falls in front of the bridge causing a forward warp. 

Many of the warped bridges I've seen have an imperfection in the grain right where they warp. When we look at bridge blanks we look for long flecks on the branded side of the bridge and the consistency of fleck helps identify if any of the grains deviate from parallel to each other(which you can view from the endgrain side). It takes very little deviation to disrupt the fleck, so it's the quickest way to observe how parallel the grains are. That's one reason that many luthiers try to pick through large piles of bridges. Once they're carved, though, you loose the flat plane that helps you observe the fleck.

[sospiri]

On ‎1‎/‎18‎/‎2020 at 11:50 AM, sospiri said:

Damage from the underslide is a fault in design. It shouldn't happen.

 

On ‎1‎/‎18‎/‎2020 at 3:55 PM, Dave Slight said:

Not really sure what you mean here.
When the bridge tips over, the tailpiece then slams into the belly (on violins and violas). The underside of the adjuster, being the highest point, makes contact first, followed by the string ball ends.

Such a large force in a small area makes some pretty deep depressions, and can lead to a crack, which usually lines up with the sound post.

Some underslides look like they were designed to punish the unwary. To me, the best design would be one which causes no damage if the bridge falls.

[Joe Swenson]

On 1/19/2020 at 7:56 PM, TimDasler said:

I've seen some bridges warp astonishingly far and stay standing, but they can also snap from warping. If you ever have a junk bridge try snapping it in your fingers. Once they're carved they're easier to snap than you might think.

Since you mention an interest in the forces at play, consider the angle of the string over the bridge. The centerline of that break angle should go directly through the bridge and stay within the bridge where the feet meet the top. If the bridge leans back the line of force falls behind the bridge and it will want to warp backwards. On violins it is more frequent that they lean forward as they are tuned and that line of force falls in front of the bridge causing a forward warp. 

Many of the warped bridges I've seen have an imperfection in the grain right where they warp. When we look at bridge blanks we look for long flecks on the branded side of the bridge and the consistency of fleck helps identify if any of the grains deviate from parallel to each other(which you can view from the endgrain side). It takes very little deviation to disrupt the fleck, so it's the quickest way to observe how parallel the grains are. That's one reason that many luthiers try to pick through large piles of bridges. Once they're carved, though, you loose the flat plane that helps you observe the fleck.

A couple pictures make it a a lot easier to see the main reason for bridge warping. This is also the most common repair I see with student instruments. The nice thing is if you catch it early enough you can repair the bridge with a flat iron and a damp paper towel on a flat surface. You can easily steam out the bend in the bridge in a few minutes.  

The force vector bisects the angle the strings make as they cross the plane of the  bridge. First image shows the bent bridge because of this mis-alignment. The second photo shows the bridge after the repair and possible recutting the feet to match with the proper alignment. Recutting the feet is necessary only if the bridge was installed improperly in the first place.