Chain Sharpening (Part 3)...

Continuing on our journey to achieving a sharp, effective chain, in this post we'll look at the depth gauges and find out one way of setting them. More after the jump...

The depth gauge at the front of the cutter fulfils an important function - to regulate how much timber is actually cut. For this reason, it's important to keep these set at the correct height relative to the cutting edge - left too high and you'll not get an efficient cut, too low and you'll try taking too much wood out in one pass.

Leaving the cutter too high will occur if you don't check and set it regularly - as you sharpen the cutting edge, the height of that edge is actually reducing, and that means that you'll not be cutting as much as you could do. So, with the depth gauge left too high, by not setting it...

  • Inefficient cutting as you could be cutting deeper.

  • Takes longer to carry out the task.

But that's just mildly irritating when compared to the potential disaster that could await you if you decide to file the depth gauges down to much, and therefore try to cut too much timber in one go. So, for filing the depth gauges too low...

  •'ll be trying to cut too much wood.

  • ...vibration from the chainsaw increases dramatically.

  • ...the saw may appear to be less powerful as it tries to keep up with the cut.

  • But, worst of all, you massively increase the chance of kickback.

The tolerances for the depth gauge are fairly small, and 25 thou (0.65mm) is not uncommon. To maintain this setting there are a number of devices available on the market, from Stihl, Husqvarna and Oregon et al.

We'll take a look at some of these later on, but for now we'll use the simplest Depth Gauge Tool.

This tool, shown in the picture, can be laid on top of the chain with the notch at one end allowing the depth gauge to poke up through. You will need to remember two things if it needs to be filed down:

  1. You must only file depth gauges on the other side of the bar to you.

  2. You shouldn't file the depth gauge with the tool in place, otherwise you will effectively be altering the measurements set by using this tool.

Whilst you might be able to see the depth gauge poking up through the tool, it's easier to use a straight edge to run over the notched end of the tool. If the depth gauge is too high then it will catch on your straight edge.

If your depth gauge tool is like the one shown in these images, you should leave the tool in place whilst you file... but lift the back end up first. This has two advantages: 1) it uncovers the depth gauge giving you access to file it, and 2) it protects the cutting edge that you just sharpened.

That's about it really, work around one side, checking and setting as appropriate before turning the saw around and doing the other side.

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