What does it mean to 'fit' a violin bridge? - Apr/May 2004
The bridge for a violin, viola, cello or bass is an ornate, structurally complex piece of the instrument that is integral to the volume & tonal character of the instrument– so much so that it’s parts have anatomical names: heart, lungs, waist & feet.
Many companies manufacture bridge blanks– pieces of appropriately aged maple that are cut to the general shape of a finished bridge. Although luthiers fit each bridge uniquely, they often begin with blanks to reduce the amount of time spent on carving a bridge & the associated cost. The illustration below shows the shape of a typical violin bridge blank (people unfamiliar with violins sometimes try to use an unmodified blank on an instrument; the results are poor).
To shape the bridge, a luthier determines the height required for playablity. For an instrument with ideal proportions & angles, the bridge is 30 - 32 mm tall; many instruments are not ideal. The luthier carves the feet to exactly match the curvature of the ‘belly’ of the instrument where the bridge rests. A perfect match achieves optimum stability & vibration transfer. The luthier arches the space between the feet to mimic the violin belly, and trims wood from the waist, lungs, heart and feet to create an optimal combination of leverage, mass & strength for transmitting string vibration to the violin body. Each part of the bridge has standardized dimensions that provide a starting point from which the luthier must derive specific proportions of height, width, arch & thickness.
For each bridge, the luthier must remove a different amount of wood to refine the shape of the heart, lungs & waist. For each bridge, the luthier must uniquely determine thickness, keeping the side that faces the tailpiece true flat; & tapering the side that faces the scroll (wood grain on the flat side should be striped; wood grain on the scroll side should be flecked). Volumes of technical papers document the research that has gone into cutting the perfect tonal bridge. A millimeter of wood is a huge amount in this world.
The finished bridge should flex slightly when squeezed gently between the thumb & index finger on the bass side of the bridge. If there is no movement, the bridge is too stiff & further refinement is necessary. Once the shape & flexibility are where they need to be, the luthier can express his/her artistic flair & simultaneously ‘fine tune’ responsiveness by putting chamfers on the sides of the bridge, the lung & heart points & the feet. The process of refining the bridge dimensions to the unique needs of a specific instrument is what it means to ‘fit’ a violin bridge. The image below shows the difference between a bridge blank and a fited bridge.
What can I do?
Seek qualified repair people to fit your bridge.
(added Aug 2015: 'self-adjusting' bridges come from the manufacturer with arching that follows a generic contour and with feet that pivot like little hinges. A self adjusting bridge is an acceptable, not desirable, alternative to having a bridge fitted to an instrument if the instrument is of modest quality and the player needs to keep the cost of fitting to a minimum. If you examine the image below closely, you will be able to see faint circular lines above each of the feet where they are pressed like hinges into the bridge)