Quick question for the violin makers about bridge curvature.

January 8, 2005 at 01:55 PM · Actually, I check by putting a 6" ruler across the D & A and another across the the G & E under the middle strings. That's what needs to be parallel. You may simply need to lower the D a little.

I can't remember the radius off the top of my head. The shape isn't quite circular, but that's because circular doesn't look good.

Is the center seam in the center? That's a common problem. If the strings do end up over to the treble side, then maybe the seam isn't in the center. Or the neck is in crooked. Or the notches in the bridge are offset. One often offsets them to the bass side a small amount. Not to the treble side.

January 8, 2005 at 06:33 PM ·

The four points established by the *tops* of the strings are on a circle (about a 42mm radius, by the way), but the line of the bridge that runs through them is not (if you think about it, this line could be anything, even two straight lines in a roof shape, and still do the job.) Many makers make a parabolic shape so the line is more dynanamic, and the bridge doesn't look stoop-shouldered.

Measuring under the strings isn't the way to do it, because the player (and the bow) plays on top, and the strings have different diameters. In your case, it probably isn't that the G is low, but that the D is high. Most of the other strings have similar diameters among types and brands, but different D strings have different diameters, and aluminum ones are thicker than silver, for instance. The standard bridge template that most shops use is made for silver D strings.

If your violin was set up for a silver D, and you have an aluminum one, you need to lower the D a bit so the top is where the top would have been with the silver D, re-establishing the string positions as they were intended. This adjustment is EXTREMELY small. Just looking at the pencil clearance won't show you what you need to see--you need to rock the string from string to string, referencing fixed objects in the background, tilting the violin each time you change strings so the pencil starting point is the same relative to the background, and noting if the pencil, after the rock, ends up in the same relative place as on the previous rotation. The difference will be subtle, but it takes very little to throw off a player.

Very often on violins which aren't new, over time the G string side of the top, supported only by the unsupported bassbar, has sunk a bit, and the soundpost under the E side, under a bit of tension pushing against the more stable back, has pushed that side up. That tilts the bridge a bit towards the G side, so that while the feet may be centered, the whole thing is leaning left. To counter that, and move the strings back (right, treble direction on the bridge) to over the center of the fingerboard, a good setup person will set the strings to the board, not the bridge, so that both the feet and strings are in the right place, possibly, though, standing uncentered on the bridge. The concept is correct, but that's not the most sophisticated and least obvious way to deal with the problem, so a player who actually is looking (few do) will see this, as you have. A better setup person will have ways to hide that this has been done, so the player won't see it.

While I was taking my morning shower just now, I counted up that in the last 24 years (this month) that I've been working on violins (20 of them on ones I could never afford to own, myself) I've learned seven ways to move the strings around on the bridge without leaving too much of a hint that it's been done, and if I used them all at once, I could move the strings almost 3mm to one side without anyone--including another maker or restorer--quite seeing how it's been done, even if they felt something was going on somewhere. :-) However, the first method I learned was to make a bridge like the one on your violin, and then plane off the extra-distant side of the bridge in a tapered wedge shape so that the strings are centered, but the taper of the sides of the bridge is different on each side, E-side vs G-side.

January 12, 2005 at 06:20 AM · Thanks for the information, guys. The D is too high.

The E&G and the A&D parallel lines is a different way of making the same check.

You could actually check the radius itself by specifying the distance between those two parallel lines. Any takers? This might be useful information when I take it back to the shop.