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carving a violin bridge


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#1 wireman24

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Posted 28 July 2010 - 08:29 PM

I started carving a new bridge for one of my violins today.
It's coming along pretty good.
The feet still have a gap less then the size of a hair.
The strobel book says to use a sanding jig to sand the feet to the top.
What do you guys think should I do it like this or just go slow and do it without the sandpaper jig.

I tried a bunch of searches on the forum about fitting a bridge but I have not seen much info.

Any suggestions would be great.
Thanks

#2 Brad Dorsey

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Posted 28 July 2010 - 08:40 PM

The strobel book says to use a sanding jig to sand the feet to the top.
What do you guys think should I do it like this or just go slow and do it without the sandpaper jig.


I recommend doing it without sandpaper. I cut the feet with a knife until I get them as close as I can visually. Then I mark them with carbon paper and scrape away the black marks with the knife blade to make the fit closer.

Edit: I do use sandpaper to smooth the faces.

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#3 STRAD~STYLE

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Posted 28 July 2010 - 08:53 PM

I just cut the feet with knife but not to crazy then finish with the sandpaper on the plate. I would like to get the jig thing with the roller on it
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#4 lyndon

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Posted 28 July 2010 - 10:09 PM

i would never use sandpaper on the visible parts of the bridge, leaves a dull finish compared to just clean the way the plane leaves it, and it also clogs the pores with sawdust which may or may not hinder the tone, there is a trick to using sandpaper on the feet, the jig never works for a fine fit, it always rocks the bridge and rounds off the bottom(although for doing a rough fit it saves time over a knife at no net negative effect), I string up the violin to 1/4 tension(fairly loose) and position the bridge already fairly well fit feet where i want it to stand then i slide 200 grit sandpaper under the feet, and carefully holding the bridge in your right hand and the sandpaper with your left hand(with the bridge at right angles at the back side to the body) move the bridge back and forth(left to right) not back to front, a little bit of sanding you will notice the bridge always wants to migrate away from the proper position, make sure you end the sanding with the bridge standing perfectly up in the right position and your done, for the more fastidious a very light scraping will eliminate any roughness the sandpaper left, the advantage of this method is you get a virtually perfect fit all the way around so you practically never find yourself wetting the bridge feet to swell up the wood to make a better fit, try it it really works much better than the jig and just as good as the finest knife fit job, sincerely lyndon :)
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#5 STRAD~STYLE

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Posted 28 July 2010 - 10:14 PM

i would never use sandpaper on the visible parts of the bridge, leaves a dull finish compared to just clean the way the plane leaves it, there is a trick to using sandpaper on the feet, the jig never works for a fine fit, it always rocks the bridge and rounds off the bottom(although for doing a rough fit it saves time over a knife at no net negative effect), I string up the violin to 1/4 tension(fairly loose) and position the bridge already fairly well fit feet where i want it to stand then i slide 200 grit sandpaper under the feet, and carefully holding the bridge in your right hand and the sandpaper with your left hand(with the bridge at right angles at the back side to the body) move the bridge back and forth(left to right) not back to front, a little bit of sanding you will notice the bridge always wants to migrate away from the proper position, make sure you end the sanding with the bridge standing perfectly up in the right position and your done, for the more fastidious a very light scraping will eliminate any roughness the sandpaper left, the advantage of this method is you get a virtually perfect fit all the way around so you practically never find yourself wetting the bridge feet to swell up the wood to make a better fit, try it it really works much better than the jig and just as good as the finest knife fit job, sincerely lyndon :)

I am a bit slow tonite i will have to read that a few more times
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#6 lyndon

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Posted 28 July 2010 - 10:28 PM

sorry its a simple process that kind of hard to explain in one paragraph,simply you position the bridge right where it belongs with the strings in low tension to hold the bridge in place then put sandpaper under the bridge, then moving the bridge left to right try to keep in all centered in the right position, sincerely lyndon
Taylor's Fine Violins, Redlands, S. California
Specializing in the research and restoration
of baroque, transitional, and modern violins.

http://www.violinist..._johann_taylor/
(violin shop ad, with links to instruments for sale, pictures of
violins I restored, and recordings and pics of my clavichords)

#7 STRAD~STYLE

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Posted 28 July 2010 - 10:32 PM

sorry its a simple process that kind of hard to explain in one paragraph,simply you position the bridge right where it belongs with the strings in low tension to hold the bridge in place then put sandpaper under the bridge, then moving the bridge left to right try to keep in all centered in the right position, sincerely lyndon

Thats one of the few things on m.n i can understand :)
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#8 Torbjörn Zethelius

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Posted 29 July 2010 - 02:25 AM

The trick to using a knife is to keep it really sharp. Personally I prefer to use a chisel. I have a 25 mm wide chisel that I use for a lot of things instead of a knife.

#9 Nicolas Temino

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Posted 29 July 2010 - 03:06 AM

Well, I use a combination of both techniques. The "secret" of the sanding jig is not to move the bridge too much (half a cm or so back and front) that way I allways get a perfect fit. Once the fit is ready I use a scraper to remoce the dust and let the surface to be a little concave, so with the pressure of the strings does the fit.
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#10 Scott S

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Posted 29 July 2010 - 03:18 AM

I use a pencil, knife and file to get a close contour. Then I tape a 2" square of 220 grit sandpaper to the top plate with Scotch brand 3M masking tape that releases easy and clean, little pieces of tape at the corners of the sandpaper square. I cradle the violin in my lap with the neck pointing away from me. Then I move the bridge over the sandpaper from north to south, only moving about 3/8" back and forth with a grip that keeps the bridge 90 degrees to the plate. I use a tooth brush to brush away the dust and rejuvenate the sandpaper as I do this.

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#11 lyndon

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Posted 29 July 2010 - 04:40 AM

scott if you continue to use tape to hold the sandpaper eventually you are going to come across a fragile varnish violin whose varnish comes off with the tape, happened to me on an eh roth in otherwise mint condition, according to the appraiser it took nearly 1000usd off the value, the only method i use is to hold the sandpaper in place with my fingers, and also if your using the jig, make sure the wheel is on the sandpaper too, this protects the finish from the wheel which can easily remove varnish from direct contact

the point i am making about sanding is that north south sanding only gets you so far, because of the indentation of the bridge in the top wood throws things off, im getting a perfect fit with east to west sanding, and you can hold the bridge a lot easier with one hand if the strings are on at low tension, sincerely lyndon
Taylor's Fine Violins, Redlands, S. California
Specializing in the research and restoration
of baroque, transitional, and modern violins.

http://www.violinist..._johann_taylor/
(violin shop ad, with links to instruments for sale, pictures of
violins I restored, and recordings and pics of my clavichords)

#12 Jacob

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Posted 29 July 2010 - 10:16 AM

Circumstances have to be ideal in order to use sandpaper-fitting successfully. I guess if I really had to, I could make it work on a new violin with a very smooth top arch. But most times I have to fit bridges on instruments where this method won't do much good. So knife and skew chisel (for spot scraping) are the tools I use.

#13 Scott S

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Posted 29 July 2010 - 10:26 AM

Lyndon, I don't use a wheel. I'd rather tape the sandpaper than run the risk of moving the sandpaper, especially the abrasive edges against the varnish, besides all of my fingers are gripping the low point of the bridge. I use my pinkys as outriggers. I've never lost varnish due to the tape. This is painters Scotch brand 3M masking tape, the stuff used for fine finishes before the new and improved that really isn't improved at all for most usage. If varnish were to come off with this tape then the varnish would have also come off due to the vibration of the instrument itself, or maybe a strong breeze.

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#14 robertdo

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Posted 29 July 2010 - 10:49 AM

i would never use sandpaper on the visible parts of the bridge, leaves a dull finish compared to just clean the way the plane leaves it, and it also clogs the pores with sawdust which may or may not hinder the tone, there is a trick to using sandpaper on the feet, the jig never works for a fine fit, it always rocks the bridge and rounds off the bottom(although for doing a rough fit it saves time over a knife at no net negative effect), I string up the violin to 1/4 tension(fairly loose) and position the bridge already fairly well fit feet where i want it to stand then i slide 200 grit sandpaper under the feet, and carefully holding the bridge in your right hand and the sandpaper with your left hand(with the bridge at right angles at the back side to the body) move the bridge back and forth(left to right) not back to front, a little bit of sanding you will notice the bridge always wants to migrate away from the proper position, make sure you end the sanding with the bridge standing perfectly up in the right position and your done, for the more fastidious a very light scraping will eliminate any roughness the sandpaper left, the advantage of this method is you get a virtually perfect fit all the way around so you practically never find yourself wetting the bridge feet to swell up the wood to make a better fit, try it it really works much better than the jig and just as good as the finest knife fit job, sincerely lyndon :)


That's a good trick. I also tried the east/west rubbing method hoping the curve of the top would be regular enough so that the bridge would eventually fit. The result was not that bad, but using the string to hold the bridge is a good idea. I will remember it.

#15 lyndon

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Posted 29 July 2010 - 10:59 AM

the wheel im refering to is on the commercial jig so many people use, and the wheel on the jig can easily do damage to varnish, since its the back side of the sandpaper thats touching the varnish i dont see how hand holding that sandpaper is going to be any risk of damage, and yes jacob theres no knocking the traditional method, certainly its more authentic, i just think with my method vs a very well fit knife carved feet; i think its very hard to say one is better than the other, certainly sandpaper can do better than a medium quality knife fit etc, sincerely lyndon
Taylor's Fine Violins, Redlands, S. California
Specializing in the research and restoration
of baroque, transitional, and modern violins.

http://www.violinist..._johann_taylor/
(violin shop ad, with links to instruments for sale, pictures of
violins I restored, and recordings and pics of my clavichords)

#16 StuartRochon

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Posted 29 July 2010 - 06:22 PM

I was taught a method of positioning the bridge with the strings fairly tight and then lift the bridge a little and slide the sandpaper under the foot. Then drop the the bridge back down on the sand paper and hold the bridge still then pull the sandpaper out. Works well on a new violin.

#17 iburkard

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Posted 29 July 2010 - 06:38 PM

This isn't really a bridge cutting/carving thread.. just about fitting feet. BORING! :)

I was taught a method of positioning the bridge with the strings fairly tight and then lift the bridge a little and slide the sandpaper under the foot. Then drop the the bridge back down on the sand paper and hold the bridge still then pull the sandpaper out. Works well on a new violin.


That sounds like the best way to destroy a finish.


The problem with sanding bridge feet is left over abrasive dust. I clean up sanded bridge feet with a knife to remove any abrasive/grit that might have entered in the wood. I tend to sand feet if I am in a hurry, and the instrument is a student instrument. I also make sure that the sandpaper is much larger (wide over the F openings) than the area where I want to sand, to prevent catching the edge of the paper (causing it to bend or skip), and to make it easier to hold with two fingers (instead of tape on the top?).
I agree with Lyndon about the tape - very bad idea even on a new factory instrument.

My advice... get a sharp knife, pencil, carbon paper and patience.

#18 David Burgess

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Posted 29 July 2010 - 06:48 PM

Off the top of my head, I can't think of any high-level luthiers who use sandpaper to fit bridge feet.

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#19 STRAD~STYLE

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Posted 29 July 2010 - 07:15 PM

Off the top of my head, I can't think of any high-level luthiers who use sandpaper to fit bridge feet.

How do they do it?
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#20 PeSt

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Posted 29 July 2010 - 09:20 PM

How do they do it?

With a sharp knife :) (and making the surface to be cut a little damp helps).

Michael Darnton has some chapters on his future book on violin making available online and cutting bridges is covered in chapter 15 in detail.

Cheers, Peter
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