CELLO BOW CAMBER

At this stage the camber has been finalized and the stick, which has been octagonal up to this point is rounded. The taper of the stick and its curve or camber is critical to how the bow will play and sound. Because of the power needed to drive the large diameter cello strings the bow must be far more resistant than a violin bow. On the other hand there is an incredible range of expressivity to the cello’s sound and without flexibility the cellist cannot access this potential. Yet there is no consensus between bow makers as to what will work best and this is for good reason because there is no consensus between fine players either. I have measured bows belonging to a number of today’s great players and they vary in every way; weights ranging from 76 to 90 grams and widely ranging camber concepts and stick graduations.

The bow maker can approach commissions it two ways. One is to simply do what they think is best and the players who like these bows will buy them. The second to tailor the bow specifically to the player but in this case one inevitably has ideas on how to reach this goal. Although I’m in the later group, the solution is not to simply copy the bows a player has. If they want another bow its because they believe they can unlock more potential from their instrument or their technique with a different stick. It is possible that something quite different would be ideal for them if they can make the technical adjustment. They have no doubt tried certain bows belonging to colleaugues that they loved. If it was a well-known maker like Dominique Peccatte or Eugene Sartory, that gives us quite a bit of information up to a point because each of these maker’s work also varies considerably. In the end the maker has to make an intuitive call on the camber, stick selection and graduations or taper that he hopes will give his or her client all the power and potential for expression they need. There is a kaleidoscopic interchange of different elements that effect the hoped for outcome, a bow that joins both power and technical response with the flexibility to bring out the full spectrum of a cello’s sound.

PLANING THE STICK

The cello bow progresses and the stick is getting planed down to rough dimensions. At this time the frog is fit on the stick so that we can adjust the stick with the frog in place.

TALON

The silver heel plate or ‘talon’ is about half a millimeter in thickness and it is fit in a shallow channel cut with knife and chisels to accommodate it. When the silver heel is fit and bent into place, the forward edge is squared perfectly straight across where the pearl slide must join it perfectly. Then it is glued and riveted with small silver pins.

At this point the dovetailed channel for the pearl slide is completed and the mortise and channel for the hair is cut freehand using different chisels. The pearl slide or ‘recouverment’ is then fit and trimmed so it fits perfectly on all sides. Finally the bottom of the frog and the heel is filed so all parts are flush with the ebony and smooth. The pins, which have been left proud, are filed off at this time and usually disappear. The pins on a new bow are tight and very difficult to see but over time the miniscule movements of the ebony frog due to changes in humidity rock the pins slightly. So in older bows the pins are usually noticeable.

The frog is now well advanced and all that remains is the underslide or ‘coulisse’ where the frog joins the stick. Here a silver lining is usually fit and pinned in place and a bronze eyelet screwed into place. At this point the frog is complete and ready to mount on the stick but the polishing will wait until the bow is nearly completed.

CELLO BOW

A cello bow is now in process and as with the violin bow we make the fog first. This is because the frog needs to ready to mount on the stick very early on in the process. Since I covered the frog making process in earlier posts I’ll only cover what is unique to a cello frog. The cello frog has a rounded heel or ‘talon’ so this necessitates a different approach in that area. The amount of curve or radius of the heel varies quite a bit between bow makers and in general the earlier 19^th century bows have a bigger radius or are more rounded. There is an aesthetic and stylistic relationship between the curves of throat and the curve of the heel. Since the length of the flat area on the bottom of the frog determines the length of the pearl slide, the rounder heels have a shorter slide all things being equal. In this case our radius is relatively large. The tighter heel curve of late 19^th century makers like Lamy was a bit easier to make and made possible a longer pearl slide since the flat area on the frog was longer.

Once the frogs heel is rounded we fit the eyes in the frog sides and in this case we are using a eye ringed with silver or ‘grain et cercle”. . To receive the ring, a narrow groove is cut with a special drill bit, which cuts the recess for the pearl eye at the same time. Each bow maker makes these bits themselves to the requirements of their taste and style. Francois Tourte was probably the first to make this type of eye and to begin with the ring was fairly heavy, getting finer during the course of the 19^th century. To make this eye a thin strip of silver is cut, bent into a ring and soldered. It is then put on a tapered rod or mandrel and hammered to the correct diameter. It is then filed until it fits snugly into its groove. The pearl eye is filed to fit and glued into its recess followed by the ring, which is hammered lightly into place. When the glue is set, any silver sitting proud can be filed off flush with the sides and the eye is completed.

FINAL STEPS

The frog illustrated in some previous posts has been mounted on a stick and the bow is nearly finished. This bow is for Antonio Anselmi, a violinist in Rome who is concertmaster of the I Musici chamber orchestra. The selection of the stick was critical for this bow as it always is for the bow maker. Anselmi plays on a late Amati with a Tourte weighing about 57 grams and he wants a soprano vocal quality to the sound. So the challenge was to find a stick with the right tonal potential of low to medium density wood. One such stick was found but ended up being set aside well into the process because intuitively it lacked too many other requisite characters. So a stick of very responsive wood of medium density was chosen and the projected weight raised slightly to 59 grams. The stick is quite powerful but much of this is placed in reserve through the cambering approach to give the stick flexibility. Several earlier bows I made with the same wood proved to have a pure, singing upper register.

In the picture you can see the unlined frog while the screw and evelet are lubricated. An unlined frog should not swing laterally on the stick as this can weaken the edges. So the frog is carefully adjusted for a snug fit. Finally the bow is measured and the camber recorded so I have the record of the bow and can duplicate aspects of it in future bows if need be. The diameter of the stick is measured in 12 places and also the height of the frog and head are noted.

Now the bow is photographed and the basic work is done. But the bow is not complete; it is now rosined and played for a day or two. If there are any final adjustments to be made to the camber they will be made before the bow is shipped.

REHAIRING

Rehairing may be the most common work done on bows but it is not the easiest. Since the most delicate parts of a bow are open during rehair, both skill and care are necessary to avoid damage. It also requires a lot of experience to select the correct amount of hair and ensure that it is of even tension. There is also a wide range in hair quality and the conscientious rehairer will use only the best, which can easily cost three times as much as ordinary hair. The good rehair person is also checking over a bow to make sure no problems arise like a frog that becomes too loose or an eyelet that needs replacing. More serious problems like an enlarged screw hole can be brought to the attention of the player. That way the problem can be repaired before the bow becomes weakened.

In addition there are two basic methods of rehairing, one in which the hair is secured first in the head and the other where the hair is started in the frog. In France the hair is always started in the frog, which ensures that most of the work takes place with the frog mounted securely on the stick. When the hair is started in the head, the frog is loose and must be placed on an often ill-fitting jig to press in the wooden wedge that secures the hair. So while a competent person would no doubt do a good rehair with either method, I think the latter method is preferable, especially for a bow without a silver under-slide on the frog.

It’s rare for a bow to be damaged in general use and more damage occurs during rehair by poorly trained people. Although the frog is quite durable as long as it is securely mounted on the stick, it must of course be removed for rehairing. Then the under-slide or channel between the frog and stick is exposed as well as the knife-edged dovetail where the pearl slide fits. These edges are sharp and delicate, especially when there is no silver underslide. They are easily chipped of damaged. This makes the selection of a really competent and conscientious bow rehairer of importance. Too often in even well known shops the bow-person is under a lot of pressure and must work at top speed. It’s a very good idea to know the person rehairing your bow and their credentials. Every player is the guardian of their bow for it can be of use for generations of musicians.

THE UNDERSLIDE.

The last step on the frog before polishing is to cut the underslide channel or coulisse where the frog slides on the stick. This is done freehand with a narrow chisel. Normally when it is completed we stamp a piece of thin silver in a press and glue it into the channel. This strengthens the area.

In this case we are leaving the coulisse unlined as Tourte and his contemporaries did in the late 18^th and early 19^th centuries. This is for several reasons. For one thing we want to minimize the weight of this bow and the silver lining weighs nearly one gram. In addition we want the tonal effect created by a frog of the lowest possible mass. And lastly the unlined frog enhanced the style of this bow, which is rooted in the early 19^th century. Contrary to some opinions, this frog is quite durable with one exception. When the bow is being rehaired the fine edges of the coulisse are exposed and easily chipped. This bow should only be rehaired by a craftsperson with the required experience.

The stick, which has already been cambered and planed down to oversized dimensions, is then planed to match the frog’s underslide in such a way that the frog is in exactly the same axis as the head. Then the mortise is cut and the stick drilled. Finally a hole is drilled for the eyelet. At this point I have outlined the whole process of making a bow starting about two months ago. So rather than repeat myself I’ll cover the following steps in more general terms and write more on other areas of importance to bowmaking. Anyone who would like to know more can go back to the earlier posts.