These brushes start as straight strip brushes and are formed into a cylinder shape with the metal on the outside and the filaments pointing towards the center. The brush is then stretched open to the required pitch, sometimes referred to as lead.
The most common brush with this shape is made with the metal channel on the inside of the brush and the filaments pointing outward. These are called Open Wound Cylinder brushes or Open Coil brushes. They start as regular wound cylinder brushes and are then stretched to the required pitch, sometimes referred to as lead. With this construction, the brush is mounted on a shaft and the filaments work as the brush rotates
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