Understanding Oregon Filing Tables

When it comes to sharpening chains for chainsaws, the filing table will provide you with all the information that you need to achieve a sharp chain.

However, different manufacturers mark their chains differently, and not all filing tables are created equally. This short presentation takes a look at how to get the information required to sharpen an Oregon chain.

Find out more after the jump...

The filing table allows us to glean certain pieces of information that we will need to know if we are to correctly sharpen the chain; things like the size of the file, the filing angle, and the depth gauge setting can all be found by using it. Watch the following presentation to learn (or revise) how to use the Oregon filing table.

Understanding Filing Tables

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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...

• ...you'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.

Chain Sharpening (Part 2)...

Back in part one of chain sharpening, we took a look at the filing tables to ascertain the file sizes and angles that we'd need to use to maintain our chain properly.

After the jump we'll take a look at how we should decide where to start filing.

Deciding Where To Start

How would you choose which cutter to start filing? When I pose this question whilst teaching, one common answer is along the lines of "whichever one is on top".

But it's not quite that simple (you knew it wouldn't be didn't you?). So, how do we go about selecting the first cutter to be filed? Fortunately it's easy, and we don't have to try finding a secret mark on one cutter, or find where the continuous chain has been joined - you just need to find the shortest one.

There's a very simple rule to this, and it's that when you have finished filing all of your cutters, they must be the same length. If they are not, you'll find that the chainsaw will not cut straight and it's disconcerting to find your chainsaw has cut the timber in a graceful arc.

If all your cutters are the same length, then take another look and see if any are more damaged than the others - if so, tidy these up first.

Once you've found the shortest / most damaged cutter, it's time to sharpen it; place the saw in a vice to keep it steady, don't try to hold it between your legs or sit on it. Ideally use a file guide to ensure that you get the right angle - don't be tempted to guess what 30^o or 25^o looks like. The angle shown on the guide should be in-line with the chain / guide bar.

Once you've sharpened this first cutter, measure the length of the cutter (shown in the picture, right). You can use a nut and bolt for this if you're a cheap-skate you want to (I do), but obviously calipers are more accurate.

Now for the Dave's 'Tip Of The Day' - mark the cutter you've just started with. It's your chance to colour in - just use a permanent marker and colour the top of the cutter (called the top plate). This will ensure that once you sharpened all the others and you've worked your way around the chain, you won't carry on by filing the one you started with!

Only file the cutters that are on the other side of the bar to the one you're standing on. If you notice the arrangement of cutters on the chain, you'll see that they are on alternate sides - you sharpen all those on one side, then turn the saw around and do the other.

Once you've completed all the sharpening, you must remove the burrs that have formed during your filing; this is easily done by rubbing a block of wood up against the cutters. This will get rid of the wire edge and ensure that the chromium plating is not removed when you start cutting for real.

So we've now got sharp cutters and de-burred them - the depth gauges come next.