The knife extension is the distance between the blade, or edge of the knife and the surface of the drum or face of the disc. The knife extension at each pocket on the drum should be the same in order to maintain a consistent knife-to-anvil clearance.
Larger extensions cut longer, thicker chips, shorter extensions produce shorter, thinner chips. Knife extension can be adjusted to produce the desired chip type.
Indications that the knife extension is incorrect include:
- Over-thick chips
- Chips are too long
- Chips are too short