Timber incising

A method of operating a machine for forming incisions in a timber plank, comprising:

• using at least two rotary incisors each comprising a plurality of circumferentially distributed teeth and rotating at the same rate to form respective patterns of incisions at a first incision depth in a common face of the plank as it is moved past the incisors, said patterns having a predetermined longitudinal alignment between them;
• adjusting said machine to form said respective patterns of incisions at a second, different incision depth;
• and
• adjusting said incisors to compensate for the altered spatial period in said patterns, thereby maintaining said longitudinal alignment between the respective patterns.

An apparatus for forming incisions in a timber plank, comprising:

• a frame;
• first and second rotary incisors mounted on respective axles held by said frame, each incisor comprising a plurality of circumferentially distributed teeth and arranged in use to form respective patterns of incisions in a common face of a plank as it is moved past the incisors;
• depth-controlling means arranged to maintain, for each incisor, a predetermined depth of penetration of the teeth thereof into the plank;
• and
• means for adjusting said predetermined depths of penetration,
• wherein the frame defines a plurality of positions at which the axle of the second incisor may be held, each position corresponding to a different separation distance between the second axle and first axle.