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Chainsaw Chain
A chainsaw chain is composed of cutters, drive links, tie straps, and rivets. The cutters have teeth that remove wood. Drive links allow the saw chain to move around the bar. Tie straps and rivets hold cutters and drive links together. While there are variations in what type of cutters are used and the spacing between them, all saw chain is composed of these four basic parts.
How a Cutter Works
For most chainsaw chain, a single cutter is comprised of a tooth and a raker. The tooth and raker are separated by a small gap called a gullet. The raker at the front of the cutter acts as a depth gauge, preventing the tooth from biting too much into the wood. The height of the raker is just slightly shorter than the height of the tooth. The tooth acts as a tiny chisel. As the chain spins around the bar of the saw, each tooth should remove one wood chip. This happens so fast that the saw appears to slice through the wood, when really the wood is being removed chip by chip at a high speed.
The teeth of a chain are arranged in an alternating left right pattern to help the saw cut straight. Because the lengths of chains will vary with different sized bars and saws, sometimes the beginning and end of a chain will have same side cutters back to back.
Purchasing Chainsaw Chain
When purchasing saw chain, there are three specs you need to know in order to get the correct chain for your saw.
- Pitch
- Pitch is the distance between any three rivets, divided by two. This translates to the average distance between two rivets, as the distance between rivets varies along the length of the chain.
- Gauge
- Gauge is the width of the drive links and where they fit into the bar. The gauge of the chain must match the gauge of the bar. If you intend on buying a chain with a different gauge than your current bar, you must buy a new bar for your saw as well.
- Number of Drive Links
- The Number of Drive Links will correspond to the length of the bar. For example, an eighteen inch bar might have 72 drive links. It is important to count the links on your old chain if the bar does not specify, as different brands might have a different number of drive links per bar size.
These three specs will usually be stamped somewhere on the bar of your saw.
Cutter Profiles
There are many types of cutters, the most common ones being semi-chisel and full-chisel. The teeth on a semi-chisel chain have rounded corners, while full-chisel chains have teeth with square corners. Full-chisel is the most common chain used by arborists doing residential tree work, and is higher performing than semi-chisel. However, the teeth of a semi-chisel chain will hold their edges better in dirty cutting conditions than full-chisel teeth.
Chain Arrangements
The cutting teeth on a chain can be arranged in different ways as well. There are three main configurations.
- Full Complement Chain (Standard Chain)
- Each pair of cutters has one drive link between them. This is the most common style of chain.
- Skip Chain
- Each pair of cutters has two drive links between them. This chain has a third fewer cutting teeth than Full Complement chain, and is usually used on long bars because the chain takes less power to operate.
- Semi-Skip Chain
- This chain alternates one drive link between cutters and two drive links between cutters. It gives performance in between Full Complement chain and Skip chain.
