I mentioned that at the recording studio I had to do some impromptu raising of the bridge by inserting strips of cardboard beneath one foot to stop a slight string buzz. Well, back home I decided to fit a new bridge. When you buy a bridge from a music shop you will notice that the feet are quite large and the profile is slightly thicker than you might be used to. That is because the bridge needs to be fitted to your particular instrument. But it is something you can do yourself.
Step one – fitting the feet
You can see how the bridge’s feet are flat, but your violin has a curved or arched top. So your first task is to shape the feet to the arch. If you have a belt or drum sander you can get close very quickly, but that is not recommended for the beginner – you can take off too much wood too quickly. So just get a small sheet or disk of 180 or 360 grit sandpaper and lay it on your violin top – with the abrasive side up! Then loosen your strings just enough so you can lift the bridge with some effort (this is so you don’t take all the pressure off and possibly dislodge the soundpost). Now slide the sandpaper underneath and holding the bridge you can either move the bridge a little against the sandpaper taking care to keep the bridge vertical so you don’t round off the feet, sand the bridge until the feet match the profile of the instrument. The other way to do it is to hold the bridge still and move the sandpaper. Be patient – it takes time. But what you are aiming for is to match the feet to the instrument so there are no sound losses.
Step two – the top profile
You will see in the photo above that there is a pencil line and markings for the proper position of the strings. I just used the old bridge for a curve template, but slid it up a little because I wanted to raise the string height a little. I then sanded down to just above the profile. This is deliberate, because at this stage I haven’t cut V-notches for the stings to ride in. The important thing is to get the profile about right by refitting the bridge and trying it for string height. If it’s too high, make a note of it and reduce the profile slightly and try again.
You will also see in the picture above, that the bridge is still a bit fat. So take the bridge out and lay some 360 grit sandpaper on a flat surface – and reduce the thickness overall using a circular or figure eight motion.
Now using the old bridge as a template, mark where the strings should go – or if you have Bruce Ossman’s book use the bridge template in there. And using a Stanley knife or sharp knife gently notch the top at the pencil marks to about half the depth of the string, and make them a V-shape so the string beds in nicely without sideways movement. These are at most half a millimetre – so it’s not much – but now you know why you sand down to about half a millimetre above the pencil line. So you are nearly there. Just erase the pencil marks with a light sanding.
Step 3 – Thinning the top
In order to impart the string vibrations to the the bridge, without the thickness of the bridge dampening the sound, there is just one more step. What you will do is to taper the bridge profile on the side nearest the fingerboard. Again, it’s a bit more sanding, but in the end it’s probably not much more time involved than it has taken to read this post – and you have the satisfaction of being able to interact more intimately with your violin! This photo shows the taper – and the finished bridge installed. Tune it up and hear the difference