Measuring Camber

Photo of Jack Estephan

I have a huge passion for sharing with those working on bows around the world, especially those of atypical countries, and have made a wonderful connection with Jack Estephan of Lebanon. Though his country is in a dire state at the moment, Jack continues to pursue his passions in music. He holds a bachelors degree in nursing, but Jack describes himself as a born musician and cannot imagine doing something else in life other than music. In 2015, he set up his own atelier focusing on bow making and instrument repairs and is the only bow maker in Lebanon I know of. He has been to France on several occasions to work with some really great bow makers; and thanks to modern technology, works with several other luthiers across the world via video messaging. It’s an honor to have an international bow maker featured here sharing his insight on camber. 

This might be a new concept to some, but the bow itself is a musical instrument and needs to be well setup for maximum playability as such. In French we say “Reglage de L’archet”, which translates to “adjusting the bow”. When a musician brings his bow to a bow technician with symptoms like weakness, wobble, and uncontrolled shaking, the bow maker runs through several elements of the bow including the weight, balance, camber, hair, and even the rosin, just to name a few. Not only is the bow itself considered, but even the playing style and technique of the musician.

DIB  “Distance In Between” is the distance between the hair and the lowest point of the camber when the bow is not under tension. 

How to measure DIB

With the hair completely loose and the frog as far forward as it will go, the bow can be placed on a flat clean surface. At the lowest point in the camber, the gap between the stick and the reference surface can be measured. Bow technicians can make this judgement quickly with a just fresh rehair and by eye very quickly. 

Violin bows can range from 0.5 mm to 2.0 mm ; Viola bows from 0.5 mm to 2.5 mm; and cello bows from 1.0 mm to 3.0 mm.

What does this measurement mean?

The DIB is to read how much camber there is in a bow and has a relationship with the stiffness of the stick. For example a stiffer stick needs a  smaller DIB and softer stick needs a larger DIB. A real world example would be if I face a soft bow with small DIB that indicates that the musician is probably suffering a lateral weakness in his bow or a stiff bow with a bigger DIB indicates that the bow suffers from a wobble. Bow makers, through experience, can tune and retune the right DIB for every unique stick. 

A well playing bow is the harmony between DIB, camber, weight, balance, stiffness, rosin, hair, musician, and a bit of magic!

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