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kayjay

Bridge feet thickness

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Greetings, 

Practicing violin bridge carving. Several sources (Strobel, Courtnall & Johnson,etc) instruct to sand or plane the back of the bridge to attain thickness of bridge feet of 4.7 mm

How precise does this 4.7 mm need to be? In other words, what is an acceptable range of tolerance around this msmt? Is 4.6 too thin? 4.65 acceptable? Just trying to understand tolerances. And if anyone might explain the effect of too thick of thin feet that will be of interest.

 

Thank you! 

 

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Depends on a number of factors, including the quality of wood the bridge blank was cut from...  Personally, I aim for 4.3 to 4.5 depending on the fiddle.

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violinbridges.co.uk is a valuable resource. Well worth the £10 registration fee to have access to measurements of lots of very nice "top shop" bridges.

 

 

 

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I know very little about bridges and bridge carving.

I love to know a bit more about this.  I just aim for 4.5mm at the feet up to right before the waist. I'm talking about the actual feet and the horizontal bar type section that extends out to the knees.

What happens if we make the bridge feet thinner?  What is happening?

Less foot surface area- but how is that going to affect sound.

More flex - but in which directions and how does that affect sound?

Is .1-.2 mm really making a difference in this area?   How so?

What is this area doing in terms of mechanics of motion and sound transference to the body?

Someone write a book on bridge carving please.

 

 

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16 hours ago, kayjay said:

Greetings, 

Practicing violin bridge carving. Several sources (Strobel, Courtnall & Johnson,etc) instruct to sand or plane the back of the bridge to attain thickness of bridge feet of 4.7 mm

How precise does this 4.7 mm need to be? In other words, what is an acceptable range of tolerance around this msmt? Is 4.6 too thin? 4.65 acceptable? Just trying to understand tolerances. And if anyone might explain the effect of too thick of thin feet that will be of interest.

 

Thank you! 

 

After you establish the back, you should be planing the FRONT of the bridge to thickness.  Not the back.

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2 hours ago, Thomas Coleman said:

And I'd like to add that .05mm is too high of a tolerance, IMHO,  for what we do.  I was taught 4.6mm as a "standard".

I believe you attended CSVM, correct?  Things change depending on who is doing the teaching. I was taught by Tschu Ho) to make the bass foot 4.4 and the treble 4.3... when I moved to the shop in Ann Arbor, the standard was 4.5. That's what I start with now.  I think it's a good thing to have a standard that produces a good result, and that is especially important in a multi luthier workshop to ensure consistency (as well as setting parameters for wood quality, bridge style, etc), but I think intentional variations of  tenth or so sometimes produce desired results without sacrificing structural integrity.  I also use smaller width bridges (39.5 mm, 40 mm) on violins that warrant them (smaller Amati and related types where the ffs are closer, etc.)

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This discussion gives a good idea of some of the nuances of set-up :)  I had a mind-opening about this the other day when I took my violin for one of its biannual visits to its maker for a check up.  It was noticed that the bridge was slightly leaning toward the scroll and I was told that that negatively affected the contact of the bridge feet on the top.  It made an improvement in the sound when the bridge was properly adjusted!

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31 minutes ago, Jeffrey Holmes said:

I believe you attended CSVM, correct?  Things change depending on who is doing the teaching. I was taught by Tschu Ho) to make the bass foot 4.4 and the treble 4.3... when I moved to the shop in Ann Arbor, the standard was 4.5. That's what I start with now.  I think it's a good thing to have a standard that produces a good result, and that is especially important in a multi luthier workshop to ensure consistency (as well as setting parameters for wood quality, bridge style, etc), but I think intentional variations of  tenth or so sometimes produce desired results without sacrificing structural integrity.  I also use smaller width bridges (39.5 mm, 40 mm) on violins that warrant them (smaller Amati and related types where the ffs are closer, etc.)

Yessir, I did study at CSVM.  I totally agree with everything you said and defer to your experience.  I wanted the OP to be aware that a 1/100 (as opposed to 1/10) of a mm was a very tight tolerance.  4.6 or 4.7 as opposed to 4.65

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12 minutes ago, Thomas Coleman said:

Yessir, I did study at CSVM.  I totally agree with everything you said.  I wanted the OP to be aware that a 1/100 (as opposed to 1/10) of a mm was a very tight tolerance.  4.6 or 4.7 as opposed to 4.65

Yup. I doubt I'd ever notice a variance of .01 mm.  :)

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I also use around  4.5 unless the bridge blank seems really strong. If I do vary between the two feet however I am inclined to make the bass foot thinner rather than the other way around since pretty much everything on the instrument is slightly more flexible on the bass side to allow for extra movement. I'd be interested to know the rational for leaving the bass side thicker.

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17 minutes ago, nathan slobodkin said:

I also use around  4.5 unless the bridge blank seems really strong. If I do vary between the two feet however I am inclined to make the bass foot thinner rather than the other way around since pretty much everything on the instrument is slightly more flexible on the bass side to allow for extra movement. I'd be interested to know the rational for leaving the bass side thicker.

I honestly don't know, but it remains in my 36 year old  school notebook.  That's not to say it wasn't reversed the next semester.  :-) I believe Tschu Ho was as experimental as any of us... and he had 28 students around to try stuff out for him.  I believe Rene may have done a little of that himself, but you'd know more about that than I do.

I tend to keep the feet pretty much the same, but will tend to fiddle with the ankles a little.

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BridgeThickness.thumb.jpeg.2bd7cd2c55aac9eb8252c773df377a76.jpeg

I thin to 4.5mm, but we need to be aware of the unintended consequences of how we accomplish this. The drawing shows two extreme ways to do this. These days I'm more conscious of the thicknesses of the middle and near-top of the bridge than I used to be. I see quite a few bridges in my shop that have been cut straight up the front, as one of the dotted lines shows. That doesn't leave many options regarding thicknesses in the middle and even near the top. I actually do something more like the bottom more-angled cut (though not that exaggerated) and then treat the middle as a separate issue, not a result.

I've seen too many bridges lately that are 4mm (or even less)  at the bottom, and straight up to the top on both sides. Where does that come from?????

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Thanks for replies so far! It sounds like 4.5 mm is the more widely implemented msmt to aim for and tolerances within 1/10th mm are acceptable (?).  If anyone has more input on making the bass foot thicker/thinner relative to treble foot I'm interested to know. 

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I tend to use 4.5 as my standard for student bridges, and 4.46-48 for mid-level bridges. If I’m cutting a bridge for an expensive instrument, I go down to 4.3 if the blank is really good and I’m confident that the player will take proper care of it.

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On 4/19/2019 at 5:23 PM, kayjay said:

Greetings, 

Practicing violin bridge carving. Several sources (Strobel, Courtnall & Johnson,etc) instruct to sand or plane the back of the bridge to attain thickness of bridge feet of 4.7 mm

How precise does this 4.7 mm need to be? In other words, what is an acceptable range of tolerance around this msmt? Is 4.6 too thin? 4.65 acceptable? Just trying to understand tolerances. And if anyone might explain the effect of too thick of thin feet that will be of interest.

 

Thank you! 

 

Probably at this point you should learn how to nail the thickness you are going for and not so much what that thickness should be.  If you ask 10 violin makers about thickness, you will get 12 answers.  Learn control first and reasoning for the rest of eternity.

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11 hours ago, Jerry Pasewicz said:

Probably at this point you should learn how to nail the thickness you are going for and not so much what that thickness should be.  If you ask 10 violin makers about thickness, you will get 12 answers.  Learn control first and reasoning for the rest of eternity.

Don't they mention 4.2 on your website article about bridge carving?

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On April 20, 31 Heisei at 6:23 AM, kayjay said:

Greetings, 

Practicing violin bridge carving. Several sources (Strobel, Courtnall & Johnson,etc) instruct to sand or plane the back of the bridge to attain thickness of bridge feet of 4.7 mm

How precise does this 4.7 mm need to be? In other words, what is an acceptable range of tolerance around this msmt? Is 4.6 too thin? 4.65 acceptable? Just trying to understand tolerances. And if anyone might explain the effect of too thick of thin feet that will be of interest.

 

Thank you! 

 

There is no answer to your question without knowing what material you use what sort of sound you are aiming at with which kind of string and string angle and on what kind of fiddle the bridge stands. 

Like almost everything in violin making, experience should rule the numbers and not the other way around. Numbers which were fixed as rule in some workshops were mostly guidelines with some possible variations. 

Without experience a simple rule to follow is always to start too thick. :D

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15 hours ago, Michael Darnton said:

You 

I've seen too many bridges lately that are 4mm (or even less)  at the bottom, and straight up to the top on both sides. Where does that come from?????

I heard that Greiner makes bridges thinner than standard rules would allow. However didn't see any of those bridges yet.

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Two of the ones I have seen, but not the only ones, have been on Greiners.

I wonder what the intent is. I can imagine that some people think it's about volume, but that seems like a misguided approach, since there are other more efficient and direct ways that don't compromise structure. That is, it's like weeding the garden by turning the whole thing over, good plants and all.

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On 4/20/2019 at 10:43 AM, Jeffrey Holmes said:

I believe you attended CSVM, correct?  Things change depending on who is doing the teaching. I was taught by Tschu Ho) to make the bass foot 4.4 and the treble 4.3... when I moved to the shop in Ann Arbor, the standard was 4.5. That's what I start with now.  I think it's a good thing to have a standard that produces a good result, and that is especially important in a multi luthier workshop to ensure consistency (as well as setting parameters for wood quality, bridge style, etc), but I think intentional variations of  tenth or so sometimes produce desired results without sacrificing structural integrity.  I also use smaller width bridges (39.5 mm, 40 mm) on violins that warrant them (smaller Amati and related types where the ffs are closer, etc.)

My ffs are a tad under 41 mm apart. What bridge width(s) would be best?

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8 hours ago, Michael_Molnar said:

My ffs are a tad under 41 mm apart. What bridge width(s) would be best?

I can't tell you what I might use without seeing other details (like where you bass bar sits), but haven't heard anything from you that would beg me off one that was "standard" (41.5), or very close to it.

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11 hours ago, Andreas Preuss said:

I heard that Greiner makes bridges thinner than standard rules would allow. However didn't see any of those bridges yet.

Yes, extremely thin. The one I saw was about 5years old and was not badly warped . I am guessing this would filter out (attenuate?) really high frequencies.

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9 minutes ago, nathan slobodkin said:

Yes, extremely thin. The one I saw was about 5years old and was not badly warped . I am guessing this would filter out (attenuate?) really high frequencies.

why would very thin bridges be more likely to filter out very high frequencies (in contrast to thicker bridges)

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