Mint-made errors are called "type-2 blanks (or planchets)" after an upending mill adds uniform, rounded rims. Type-2 blanks may also be considered striking errors as they are prepared correctly, but are released without having been struck. A misfeed can occur when the metal strip is fed through the blanking machine. The punches sometimes overlap the leading edge of the metal producing a straight clip. Sometimes, the punches strike an area of the strip which overlaps the hole left by the previous strike producing a curved clip. Sometimes punches strike the irregular trailing edge of the metal strip producing irregular clips. Coins are
Eight Pieces for Four Timpani Eight Pieces for Four Timpani Eight Pieces for Four Timpani is a collection of short pieces by Elliott Carter for solo timpani – four drums played by one musician. Six of the pieces were composed in 1950. Two new pieces were added in 1966, and the rest were revised in collaboration with percussionist Jan Williams. Carter wrote the pieces as studies in tempo modulation and the use of four-note chords. They are a collection rather than a suite, as Carter suggested no more than four be performed at once. The pieces make heavy use of extended techniques, including playing with