4 mins
New angles on an old problem
Lutherie
Points of interest to violin and bow makers
The device is made from a metal rod, clamping block and a fixture for regluing ribs
There have been many theories and beliefs about neck projection and fingerboard height. One is that violins sound best with a spacing of 5-7mm between the upper edge of the top and the gluing surface of the neck/fingerboard (commonly called the ‘overstand’), and with a 27mm projection at the bridge, measured with a straightedge on the top of the fingerboard (see figures 1 and 2). These specifications have been passed down for at least two generations, and have a lot of experience to support them.
FIGURE 1 The standard way of measuring neck projection
FIGURE 2 Measure the overstand
FIGURE 3 Measure the string angle over the bridge
Another, more recent specification has been a string angle of 158 degrees over thebridge (figure 3). Still, uncertainty remains about the ‘optimal’ set-up, particularly because no instruments, or their players, are identical. And if these specs are o. by as much as a degree or a millimetre, some people in our trade will recommend correction. Does this actually do anything meaningful, or is the change more psychological?
At the Oberlin Violin Makers Workshop a few years ago, one of my colleagues brought in an experimental violin with an adjustable overstand. If I remember correctly, the neck angle could be changed as well. This is a great learning tool for discovering some general concepts, but it wouldn’t necessarily reveal what would work best on a specific violin that you want to improve.
Another strategy is to keep an assortment of ‘self-fitting’ bridges (those with pivoting feet) in various heights, which you can slap on to a violin to get some idea of what a contemplated change in the neck angle will do. I think this is a vastly better strategy than altering an instrument based on assumptions.
However, this introduces multiple variables and it becomes di. cult to isolate one from the other. Does the higher or lower bridge sound different because of a change in the downforce on the bridge, or is it from having changed its mass and ‘rocking frequency’?
There are also other methods, such as putting a temporary shim between the saddle and the tail adjuster (figure 4). But this, too, suffers from multiple variables: for instance, the distance between the bridge and tailpiece does not remain the same, and too much time elapses between A/B comparisons.
FIGURE 4 An experiment using a saddle shim
FIGURE 5 Fixture as originally supplied
FIGURE 6 The device allows the tailpiece to be lowered…
…and raised as required
ALL PHOTOS DAVID BURGESS
I’m very much into ‘quick and dirty’ experiments in order to move forward speedily. So I thought it would be fun to come up with a way to raise and lower the tailpiece easily. is allows me tovary the string angle and the downforce at the bridge while changing little else, and preferably without needing to remove and reinstall the bridge, strings and other accessories - or even retune the strings - so there will be the smallest amount of time between comparisons. (Why the emphasis on time constraint? Because detailed memory for sound goes down very quickly as time elapses.)
So I came up with the lovely device shown at the top of the previous page. is is based on a commercially available .xture used to reglue the ribs to the bottom-block fiure 5), with the addition of a metal rod and a clamping block. As you can see from the pictures in figure 6, the tail adjuster can be easily slid up and down the rod to change the downforce or string angle, without even needing to loosen the strings. If the angle of the rod is just right, it doesn’t even require the tuning to be corrected. (Application of some bar soap or wax will make it slide more readily.) e angle I used for the inserted rod was ten degrees, but this willvary from one instrument to another, and will also depend on how much compressible padding you use between the surfaces of the wood. An easy way to adjust the rod angle between one instrument and another is to apply layers of tape to the clamping block where it meets the edge of either the top or the back.
I’M VERY MUCH INTO ‘QUICK AND DIRTY’ EXPERIMENTS IN ORDER TO MOVE FORWARD SPEEDILY
I would not recommend simply drilling and installing the metal rod in the clamping block, which was originally intended for another purpose. e one I originally fashioned was made this way, and while it worked well on some violins, the forces proved to be too great for some violins with a weak glue bond between the top- and bottom-blocks. So I decided to make a new block which was larger, to bear on the top and back plate edges, rather than on the ribs alone.
A full-sized tail adjuster would be too long for what we are trying to accomplish here. Instead, I chose a fractional-sized tail adjuster to keep the afterlength (the distance between the bridge and the tailpiece) within normal values. e one I used was marketed as being appropriate for 1/4 to 1/16-sized violins.•