page_title: Saw chain
section_title: Scratcher teeth
hierarchical_section_title: Saw chain / Early saw chain designs / Scratcher teeth
caption_attribution_description: A section of "scratcher" chain on a chainsaw bar nose
context_page_description: The saw chain, or "cutting chain", is a key component of a chainsaw. It consists of steel links held together by rivets, and superficially resembles the bicycle-style roller chain, although it is closer in design to a leaf chain. Its key differences are sharp cutting teeth on the outside of the chain loop, and flat drive links on the inside, to retain the chain on the saw's bar and allow propulsion by the engine or motor.
  Saw chains are used for cutting wood. This may be for harvesting trees for pulp or timber, for tree surgery, or for processing firewood.
  Whether for hand-held chainsaws, mechanical timber harvesters or chain mortisers, the saw chain has undergone dramatic development since its invention. Modern chains designed for high power, high-speed sawing applications will vastly outperform older designs, while allowing a far greater degree of safety and reliability in use.
context_section_description: Very early chainsaws used tooth configurations very similar to conventional hand saws. These were very simple saw teeth following a wave pattern (left, centre, right, centre) with no depth gauges as such, relying purely on bar pressure to limit the cutting rate. They were inefficient and slow in use, and were soon superseded by chipper chain. They required great skill and a lot of time to sharpen in the field leading to extended downtime between sessions.
caption: A section of "scratcher" chain on a bar nose, showing the tooth layout.
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