Cut A Bridge, How?

[Fellow]

Hi All,

I remember some years ago the luthier in a local shop cut a bridge for me

while I watched him. It looked so easy. I do not remember he thinning

(cut the thickness down) the plank. I assume the blank needs no shaving.

Recently I bought a few blanks (bridge) they are so thick, so trimming top and feet alone

would not be enough to make them fit. How do you make them thin? Sand them

with a power grinding wheel (which I do not have) or sand paper them ( a lot of sanding)

Why they do not sell thin bridge planks? Or they do. Curious.

Before I go for a professional help ($80 a bridge, quoted) for a few hundred dollars violin?

Does not make sense to me. Advice please.

[Marilyn Wallin]

hello Yuen,

Bridge blanks need to be carved or planed on every surface. The

usual tool for thinning the bridge is a well tuned block plane.

(not something one can explain without a physical demonstration).

The feet are fit, flat to the surface, no hollow in my opinion,

with a straight edge knife, single or double bevel, makers choice.

Then the height is carefully determined and strings slots created.

Then the top edge and front arch are created (again with the block

plane). Then the openings are all adjusted according to the tone

desired from the instruments, with room for coaxing the sound one

way or another. Things are beveled and cleaned and made beautiful

with the best workmanship the maker has. Then a light polishing

with 400 and then 600 grit and then 1000 grit to remove plane marks

and polish the bridge, a light dry powder coloring, a drumskin, and

you are done.

A good violin deserves this kind of attention, a lesser violin

still needs a bridge that will not damage the violin with poorly

fitting feet, and will not drive the player crazy with a bad sound

or a bad arch and string height.

Marilyn Wallin

[Collin]

I agree with Marilyn, but my approach differs slightly.

I'll go through what I do.

First, fit the feet. I start with sandpaper (my results are more consistent, and allow for more fine-tuning later when I use sandpaper to start). I lay the sandpaper so that I can see one of the f-holes, and line the bridge up with the nick. The back (the side with the stripes) should be perpendicular to the top, though with taller bridges, I will tilt it minutely towards the fingerboard to prevent warping. Anyway, once it is lined up with everything, I sand the feet down by moving the bridge north to south (fb to tp). I then take a sharp, staight-edge knife and, with the blade vertical to the bottom of the foot, scrape down the middle of the foot until the knife makes full contact. I line the knife up using a lamp behind the brdge and knife, and then look at the gaps, if there are any, on the sides of the foot. I make the feet very slightly hollow east to west, and then lick the feet before stinging it up.

If the bridge previous to mine has a good height, I will mark where the string notches are, and then trace my arch onto it so that nothing really changes, unless something should change. I then cut the top down using a small plane at first, using long strokes that follow the curvature, that is, not making straight cuts with the plane, but keeping the mouth in contact and varying the pressure to follow the curve I marked. I know that sounds complicated, it really isn't. I finish it up with sandpaper. I then mark the notches with a pencil and file them down. For the e-string, I sometime use a very small snakewood insert, but I normally use a small peice of parchment soaked in superglue and put on with a tweezers.

Then, I use the same plane I used before to fit the top, and cut the front, and, to an extent, the back. I could go into a lot of detail behind this, but a previous discussion does this better:

Bridge Profile

With the heart, kidneys, et cetera, whatever you do, take of very little with each stroke of the knife. After a while, you will get a feel of how much you can safely take off, 'till then, always take off less than you think you should. The above will show you the the basic shapes you can get - but here are some pointers for sound. opening the kidneys out and up, and the heart up will brighten the sound, as will a thinner bridge. Not doing either much, and leaving the bridge thicker will give a darker sound. You may want to cut down the waist a little, but I'll let Joseph Curtin talk about that.

<B"><B">http://www.joseph...tudios... violin setup

[/L]

Good luck!

P.S.: Starting out with a very thick blank allows for more freedom with the finished bridge. Some instruments like thick bridges. Others don't.

[PicknBow]

Collin,

Don't most luthiers fit the feet first?

[Collin]

Yes, and so do I. I'll fix that.

Oops...

[Jacob]

Yuen, some people cut their own hair (I do, my hair isn't worth even a $1 haircut).

However, I won't try to extract my own teeth, regardless of the quality of the instruction.

I guess you have to weigh the potential pain, damage and wasted time against the potential financial saving when pondering to cut a bridge yourself. For myself, I'd go for $80 rather than $3 for a cheap blank, any number of wasted hours - and $80 on top of that after all.

[Fellow]

True, Jacob,

I am not under estimating the difficulty of cutting a bridge. I have tried two times both times failed.

(one bridge was too thick, one almost done but I had broken a foot) I may try to find a lower quote if I would let my violin shipped out of town.

It all adds up the same about $80. The situation now I just accept it as a fact of life, not think too much about it.

All the sudden, I felt so good. Thanks.