Pitch And Gauge...

The chain has got to be one of the most important things that you'll purchase for your saw on a regular basis; it's designed to fit around the guide bar, and it's important to get the correct chain for your bar / saw. There are three basic considerations to get right when purchasing a new chain:

Find out more about these considerations after the jump.

Determining Your Chain

1. It must have the correct pitch.


2. It must have the correct gauge.


3. It must be the right length.

Pitch

As with a bicycle chain, the chain itself must fit around a couple of sprockets - one by the pedal, and one on the wheel; fortunately you don't have to pedal a chainsaw but there are still two sprockets that our chain must fit. The pitch of the sprocket must be the same as the pitch of the chain.

The pitch can be determined by measuring the distance between three rivets, then dividing this distance by two. Why three rivets? Well, because the rivets are not spaced equally around the chain and if you look closely at your chain you'll find that the spacing goes close, not-so-close, close, not-so-close, close... you get the picture.

Fortunately there are standard sizes of pitch: 1/4", 0.325", 3/8" and 0.404" and you can either measure it, look at the box your original chain came in (you did keep that, right?) or look on the side of the guide bar as it's often etched in there.

Gauge

The second important measurement when it comes to ensuring we get the right chain is the gauge - this is the thickness of the drive link and it's got to be the right size to fit in the groove of the guide bar.

There are common sizes for the gauge, interestingly (and I use the word in it's loosest sense) these measurements are often in metric, unlike pitch which is in imperial. Anyway, the common sizes are 1.1, 1.3, 1.5, 1.6, 1.8, 2.0mm.

Chain Length

The length of the chain is obviously critically important too, but what is surprising is that just knowing the length of the guide bar is often not enough to ensure the right chain. This is because an 18" bar on a Stihl requires a different length chain to an 18" bar on a Husqvarna, so a better system was needed to ensure the correct length.

The length of a chain is properly determined by the number of drive links, this is often etched on the side of the guide bar - or you can sit there and count them (just remember which one you started counting at).