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Properly fitting bridge feet

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One of the techniques I'd like to improve on is the proper fitting of bridge feet. I get the theory of a perfect fit, what I'm having trouble with is the technique to accurately hold the bridge in place during the fine fitting process.  I find I rock the bridge which leads to inaccurate markings during fitting (i use graphite on paper to transfer the high spots).

 

Any advice, tools, fixtures and techniques you can share would be helpful!!

 

Best,

 

Chris

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The final fitting with graphite or chalk should be to improve the fit beyond what you can see. If you fit by eye until you can't see any gaps at all with the bridge standing in place by itself and check for any twist by gently pressing opposite corners of the feet down,then the bridge can be held down in place with one hand while moving the feet just a couple of tenths of a millimeter with the other and it will mark the higher spots so you can scrape them off. The thickness of the paper you spoke of is larger than the corrections you are trying to make and that is throwing you off.

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You can use actual carbon paper for more precision (thinner paper).  Also I hold the bridge still and gently pull the paper (making sure you don't lift up as you pull).  

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The final fitting with graphite or chalk should be to improve the fit beyond what you can see. If you fit by eye until you can't see any gaps at all with the bridge standing in place by itself and check for any twist by gently pressing opposite corners of the feet down,then the bridge can be held down in place with one hand while moving the feet just a couple of tenths of a millimeter with the other and it will mark the higher spots so you can scrape them off. The thickness of the paper you spoke of is larger than the corrections you are trying to make and that is throwing you off.

What Nate posted is right on. I would add that if you are right handed, set the instrument in the ring with the scroll to your left. Now if when you hold the bridge in place with your right hand for mark transfer, have your arm resting in place so that it lines up with the fingerboard, essentially on the center joint. This will minimize unwanted movements, and also you will acquire a feel for the angle of the feet.

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thanks!

 

Also what is a good safe way of marking the top for the bridge position? I've tried various things on scraps like pencil and crayon but i cant seem to get a good clear line -- at least one that doesn't leave a permanent mark on the varnish.

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thanks!

 

Also what is a good safe way of marking the top for the bridge position? I've tried various things on scraps like pencil and crayon but i cant seem to get a good clear line -- at least one that doesn't leave a permanent mark on the varnish.

Here we use sticky labels.

https://trianglestrings.com/carving-a-violin-bridge/

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fantastic article Jerry. 

 

I'm trying to increase my skill level and do the whole operation with a knife and chisel, and this article is very helpful. Also does a nice job of showing your clients whats involved in doing a quality job and gives team some profile. Nice!

 

Craft skills like fitting a bridge require experience and repetition -- quite  challenging for amateurs who only set up an instrument once every year or so

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Craft skills like fitting a bridge require experience and repetition -- quite challenging for amateurs who only set up an instrument once every year or so

I will relay the compliment to Ryan.

Yes it is challenging. However, with good technique and a solid understanding, even doing them once or twice a year can be very successful. I find that once these are in someones head, it may take a little longer but the results will match the minds eye.

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This is probably overkill, but prompted by that same dissatisfaction with my ability to keep the bridge on the same precise location whilst fitting I made this jig. The vertical screw adjusts the angle of the bridge while the horizontal screw locks the lateral registration arm. I have a huge stock of old school credit card slips and so I use those under the bridge, pulling it towards the fingerboard without lifting the carbon up and giving a false impression on the fingerboard side.

If this interests you I'll post my schematic, but you can probably fake it on your own. It was such a pain to make it out of 1/4" acrylic that I'd recommend almost any other material.

Jerry's bridge fitting link, along with Michael Darnton's chapter, constitutes my bridge bible. Amazing free resources!! Thank you gentlemen.

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Nathan, I edited a longer post which serves no purpose for people who
insist on using a knife for everything, so knife type remains the only consideration. 

I put the violin in the cradle and use two hands to move the brigde up and down the table half an inch.
Holding the bridge at the feet helps. 

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I'm out of this discussion for I place a strip of 3M Micropore surgical tape across the area of the bridge, one string to hold the bridge, then pencil scribe the feet marks, and finish on a spindle sander. But I was asked once to make a bridge for a very old cello ( somewhat valuable) and learned an unforgettable experience of bridge fitting, especially with the person who owned the inst hocering over my shoulder. From routine bridge fitting with sort of new inst's to this- I think by the time I fitted most of the lumps and valleys I was more of a wreck than the owner. Never again.

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thanks!

 

Also what is a good safe way of marking the top for the bridge position? I've tried various things on scraps like pencil and crayon but i cant seem to get a good clear line -- at least one that doesn't leave a permanent mark on the varnish.

 

I use little"points" of low tack tape, like drafting tape, to mark the location of the bridge.

 

The only thing I might add to the excellent advice you've already been offered is that a common difficulty I see when I watch others fit a bridge is when there is a "twist" in the feet.  If the angles are correct, the bridge will be very steady on the top and relatively easy to mark (kind of like a fresh hollow grind feels on a sharpening stone). If a small twist is present, the feeling is not as secure and tends to wobble a bit... and you can end up chasing shadows, so to speak.  If you sense a twist, try guiding the fit by favoring your hold on the side that you determine is correct and cut the print you make (with light pressure) on the other foot (should be pretty obvious once gathers the graphite or chalk)... until both feet are steady on the top.  

 

Hope that helps.

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One way to check for the "twist"  Jeffrey is talking about is to press lightly on the front outer corner of the foot and the back outer corner of the opposite foot. You will feel the bridge rocking if the feet are not both fitting at the same time. Do the opposite corners as well, This is easy on a cello, On violins I use a couple of stout needles to press on the corners. This should be checked frequently or you may be fine fitting each foot individually while they are way off when both are touching.

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One way to check for the "twist"  Jeffrey is talking about...

 

I check by tipping the bridge slightly -- pushing the top of the bridge a bit to one side (i.e., towards or away from the neck), not far enough for it to fall over, then releasing it and allowing it to teeter back and forth until it settles back into a stationary standing-upright position.  I watch and listen as it settles.  A bridge that does not fit well will wobble and rattle as multiple points on the bottoms of the feet come into contact with the top.  One that fits well well behave noticeably differently as it settles, because it will tip one way until the edges of the feet contact the top then back the other way until the edges on the other side contact, without any intervening points of contact.  It's a bit hard to describe, but the difference between a poorly-fit and a well-fit bridge can easily be discerned by how they behave when they're tipped and released.

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Great article Jerry

Lots of good advice already. I would add that it helps to have 2 100 watt bench lamps so you can put good light on both sides of the bridge during fitting. Decide what you expect to see from the graphite markings before you look at the bottom. Don't trust the graphite blindly, but use it to help confirm your expectations regarding the fit. If you're unsure if you see a little gap try tipping the bridge back and watching the way the gap changes. Sometimes this helps you identify the gap a little better. Leo check the fit occasionally with no pressure on the bridge. You don't want to hide gaps with string pressure rather than getting a better fit.

I would avoid using a jig to hold the bridge because it will slow you down and make it harder to inspect the rock and fit by eye.

I like to use a 1" butt chisel with a curved grind. It fits nicely in your palm, and you can flip it over to nick off a high spot with lower risk of catching somewhere you didn't intend. Usually I use it flat side down, though, so the curve helps by allowing you to hold the chisel at any angle to the bridge without being out of plane with the surface that you're cutting. I end up using this chisel for most fitting tasks. Crown has good steel, but it's tempered soft. If you're comfortable annealing/tempering it I would recommend it.

When fitting the bridge feet I flip it over and hold it on my chest as shown in the photo. Keep your elbows tucked in and keep fewer joints free floating. You'll have more precise control this way. Cutting this way. All the cutting action is now limited to just a few joints in the hand/wrist.

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Thank you everyone for your fantastic advice! My goal this time was to fit the bridge entirely with a knife and or chisel. I think was able to do a reasonable job (the bridge stand upright on its own and i wasn't able to see any light pass through the feet. Your guidance here helped me turn the corner from a task I use to dread to one i now enjoy! 

 

Chris

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post-45462-0-46710400-1456236659_thumb.jpg

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Another useful hint to increasing your speed and precision is to occasionally cut a 'speed bridge'. It's an irritating thing to do at first, but you set a timer and give yourself a limited time to complete each part of the bridge. 1 hour is a good starting place for a 'speed bridge'. From this process you should learn to make fewer cuts to reach the same place, and make better judgements about how much material to take at any given time. While the marks on the feet may tell you where to cut the size of the gaps will tell you how much to cut. Repitition will make it easier to close that gap in ferwer attempts. Limit wasted motion and both speed and quality usually go up. You might not end up using those speed bridges on instruments, but think of them as etudes.

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The thickness of the paper you spoke of is larger than the corrections you are trying to make and that is throwing you off.

 

When I use carbon paper I slip a small piece under the "other foot" to level the playing field...small enough that it doesn't get in the way of the position marker.

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