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Goran74

Bridge fitting methods and differences

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Most of the well respected luthiers fit the bridge's legs using chisel or knife and tracing with ex. pencil dust. There is also the method of the "bridge fitting tool" (that small jig with a wheel) and sandpaper (turned upside down). Which are the differences and the + or - of both processes? I was always finding the sandpaper method faster and safer. 

Thank you

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Unless the top has no feet depressions the jig with wheel is not a bad way to start. However watch that the wheel does not make marks on soft varnish. I put electrical tape on the wheel to mitigate that on student instruments. The pros will start yelling that the jig with wheel is "amateur hour" so get ready. I never do that on a quality instrument. It is easier for a less experienced repairman to fit the feet correctly with the jig. For better instruments I go back and forth with carbon copy paper and a grease pencil. Not definitive on which is better. If you have impressions on the top from the bridge feet get ready to earn your money.

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I like to cut the sticky portion of a post it note and fit it at the diapason. I'll use a white chalk that has some clay binder in it for indexing. The adhesive on the post it is so low that there is no chance of it pulling any varnish off. Or at least it hasn't done that for me yet. But if you're concerned then err on the side of caution. 

The tools that I use are a knife with a slightly curved profile to the bevel and a 1/2" chisel. 

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9 minutes ago, David Burgess said:

Fitting bridge feet with sandpaper is great! :)

Another method:

 

Flipping brilliant!!!!!  :lol:

For those who may be unaware of David's comedic skills, "Kids, don't try this at home".  :)

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7 hours ago, scordatura said:

and a grease pencil

 

7 hours ago, Nick Allen said:

white chalk

Thank you all for your answers. I used with success oil pastel crayon. After application, I wipe it off with a cloth and an oil drop. Also I use chisel for feet - for some reason I cannot use effectively the knife or I do not have the proper tool.I have a straight one but it is a bit thick. With the sandpaper the process is a bit faster but I do not see amateur results with this method.

(** haha these videos are standard response on such questions... one day I will try - I have a jackhammer instead of a drill - procedure will be much faster..)

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A good sharp chisel can get you close to a good fit. A good curved knife will take you the rest of the way. The knife blade needs to have a curved edge so that you can remove wood in precise spots on the slightly concave surface of the bridge foot.

Grease pencil, chalk, carbon paper, and soft pencil, are all good ways to help you see where wood needs to come off, but your most important tool is your eye. It takes a while to develop a sense for fitting the feet, but it will take your skills to a much higher level when you develop it, and you’ll find that that attention to detail will translate into other aspects of setup, like fitting soundposts. 

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I made a positioning jig that I use to make sure the bridge goes back exactly to the same spot at the same angle every time I put it back down. I have posted a photo before, but I can't seem to find it at the moment. I use carbon paper to check the fit, salvaged from old credit card slips, which is nice and thin. I use a large-ish curved knife to fit the feet.

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19 hours ago, David Burgess said:

Fitting bridge feet with sandpaper is great! :)

Another method:

 

The best part about the second method is that you can burnish the back at the same time!

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3 minutes ago, David Burgess said:

Not nearly as well as my friend and colleague, Peter Goodfellow.

 

You have no idea how much I'm laughing right now!!! Has anyone tried with one of those machines that chop trees down and remove bark?!!!!!! Sorry @Goran74 but these moments are priceless

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1 hour ago, jezzupe said:

nah' that's for arching and graduating :)

Isn't that what power chisels are for?  There's even a quote from a classic 1950's New Yorker article proving that it's a traditional technique of the Schönbach/Mittenwald/Bubenreuth school:

On 12/15/2018 at 8:45 AM, jacobsaunders said:

From a room near the rear entrance came the sound of machinery, and, looking in, I saw two men cutting double-bass scrolls out of blocks of wood with electric chisels.   Shavings flew through the air like snowflakes in a blizzard. 

I feel that using modern, compressor-driven air chisels would give much more authority to the cutting.  :ph34r:

 

 

 

 

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5 hours ago, JacksonMaberry said:

I haven't, but mine is functionally identical - though made of 1/4" Plexiglas, and held in place with rubber bands rather than clamps.

From one IU guy to another, do you have a pic of your jig? ;)

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13 hours ago, scordatura said:

From one IU guy to another, do you have a pic of your jig? ;)

I looked through my Instagram and my bench thread to no avail, sorry! I'll keep you in mind and get a photo up, though. I know there's one on my old Facebook, but I deactivated it a year ago

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I have suspected for sometime that my 2,000 pound 2 hp Bridgeport type mill is under powered (i.e. not sufficiently manly) for many violin related tasks.........;)

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