It’s not just a case of saying that it’s a case of the violin having a key. It is, quite broadly speaking, a case of a violin having a key that fits one or more strings. That’s not to say that every violin has a key, or that every key is used for one instrument. But it is an assumption: that a violin’s key can be easily identified.
So what is a key?
Key is a term for a type of metal alloy, sometimes called a “finger-type” or “finger-free” alloy. In general, a key is an alloy composed of two or more parts that have an alternating number of sides (called the axes).
In a key, a series of alternating faces on each side of a piece can be separated by a continuous line. The series of faces on different axes always align each with the other.
In order to make a key, the key is cut into small slivers, usually a few millimeters by a millimeter, using a rotary saw or chisel. The slivers are then heated to a high enough temperature that the sides that line up with the axis and the side faces that align with the axes are hot enough to melt.
There can be several keys on a violin because there’s a large number of axis alignment faces on a single piece. The angle and alignment faces in a key are called axes, and in order to make a key, the key is cut up to a uniform size and then cut into slivers with a rotary saw. The axes of a key lie in a pattern that reflects the orientation of the slivers on each side of the main axis.
What is a violin’s instrument, then?
We’re not talking about a violin with no key here. Here, we’re thinking in a sense of “the violin with a key”, i.e. a violin with the key that fits the strings. For example, in the early years of the violin, the key was a large screwdriver, similar in shape to a mallet.
In the modern world, violin owners frequently choose to replace the key, sometimes at the expense of making the instrument more comfortable and easier to move around. The key is still useful for adjusting the neck, but as instruments have become less about adjusting the neck, tuning and all the other functions of the violin the key has become of little use. It’s mostly an aesthetic concern, the key making the instrument feel