Understanding Chain Ident.

Over the last few chainsaw maintenance courses that I've run, it's become obvious that there is some confusion over how to identify a chain. So, if this is something that you're not entirely sure about, here's your chance to get it nailed. Read on for more information...

Perhaps the easiest way to find out how to identify the chain correctly is to have a look at the following table. We'll just stick to Oregon, Stihl and Husqvarna...

	Oregon	Stihl	Husqvarna
No. on drive link	ID #. Look up in filing table.	Chain gauge. Ignore for now.	ID #. Look up in filing table.
No. on depth gauge.	Depth gauge setting in thousandths of an inch.	Chain pitch. Look up in filing table.	N/A

For Oregon and Stihl chains you'll also need to compare the cutter profile with that described in the filing table - that way you'll ensure you are looking at the relevant chain information.

Take a look at this previous post if you need to convert between Stihl's terminology for cutter profiles and others... Name Your Chain

Working Edges: Part Two.

In the last post we looked mainly at how cutting angles affected the working edge and how not using the file with an even stroke causes the working edge to become rounded. In this post, we'll compare the working edge of a semi-chisel cutter and a chisel cutter - and look at one of the most common faults when sharpening the semi-chisel version. Find out more after the jump...

We of course know that the working edge should be kept at the correct angle and that the edge itself should be straight. This is pretty easy to see when maintaining a chain with chisel cutter as the top plate very definitely meets up with the side plate. After all, it's this that gives the chisel cutter its characteristics - the working corner that comes to a well-defined point that allows the wood fibres to be severed.

However, the semi-chisel cutter does not have this same defined point as there is a curved surface between the top and side plate. This affects the working edge as it no longer stretches the entire width of the cutter, in fact, it almost looks as if the corner has been knocked off or made blunt! The main thing here when sharpening is to ensure that there is a straight edge running from one side to the other side of the top plate - and this is where I see many people who are just learning to sharpen get it wrong. They tend to stop filing slightly too early, achieving a straight edge which, unfortunately, does not go right across the leading edge of the top plate; placing a straight edge against it shows up the problem. The solution? On most occasions it takes just one or two more strokes of the file to sort it out.

I tend to use the straight edge of a file guide to check this leading edge, it just acts as confirmation, but you should be able to see it fairly clearly in good light. You'll see where the curve starts as it leads from the top plate round to the side plate - there'll be a difference in the way the light hits the cutter and it shows exactly where the edge of the top plate is. Follow this line forward to the working edge and make sure that it's straight from this point to the other corner of the top plate - hopefully the picture shows this better than I can explain it.

Working Edges: Part One.

Post number three in this quick look at common sharpening problems takes a closer look at the working edge of the cutter. This is the crucial bit that slices through the wood and so it must be sharpened correctly. I've seen a number of common errors when filing the cutters and getting the working edge correct is probably the most difficult. Click on the jump to find out a bit more...

There are a number of things that need to come together to end up with a good sharp chain that's capable of cutting effectively and efficiently. When we sharpen a chain we need to know:

1. the file size;


2. the filing angle;


3. the depth gauge setting.

We've already seen in the previous post that selecting the wrong file size will affect the side plate angle, or the amount of hook, given to the cutter; and this time we'll have a look at the issues surrounding the filing angle.

The filing angle, given by the manufacturers, lets you know the best angle for the type of work that the chain is to be put to. For example, a crosscut chain will have a filing angle between 25^o and 35^o, whereas a ripping chain is much shallower - the ideal is 0^o but values in the range of 5^o to 15^o is more common. This is because of the different way the cutter has to remove the wood when cutting across, or with, the grain. Cutting across the grain (cross-cut) the cutters must be set up to sever the fibres, when cutting along the grain (rip-cut) the cutter must essentially chip the wood away. We'll take a closer look at rip cutting and cross-cutting in a later post and see how it actually works.

Back to our filing angle; there are several ways of filing the cutter - from using just the file on its own, to using a Dremel with an attachment, through to the professional grinding wheels for accurate setting. Each has it's own merits and drawbacks (perhaps that could form another post in the future!). Here, we'll stick to using the good ol' file with a file guide.

The potential problem with using just the file is that you have no control over the height that you are filing at, making it all too easy to set the incorrect side plate angle. The file guide, used properly, should reduce the chance of this - notice that it doesn't completely alleviate it as you can still place it incorrectly or put too much pressure down on it. But it helps, and it's also got the lines etched in to it to make lining it up to the correct angle a simple task.

Stihl recommend a filing angle of 30^o with their Rapid-Micro and Rapid-Super chains which makes it easy to remember, but you need to be a bit more careful with Oregon chains, even those with the same identifier on them. An Oregon #21 or #22 chain could have it's filing angle set to either 25^o or 30^o depending on whether it's a 'round ground chisel' chain or a 'micro chisel' chain.

Once you know the angle, the problem then is that it can be hard to achieve if your filing stroke is not even. The picture at the top of this post shows what happens if you change the angle right at the end of the stroke; you can see that the working edge of the cutter is no longer straight. To correct this, make sure that you keep your filing stroke completely straight from the beginning to the end, and maintain an even pressure.

In the next post we'll continue with the working edge and the difference in shape between a chisel cutter and a semi-chisel cutter. Chisel cutters tend to be very easy to file with a straight edge all the way across, but time and again I see semi-chisel cutters not done to their best, so we'll pick up on this and have a look why...

Cutter Lengths.

Continuing our look at common problems encountered when sharpening the chain, in this post we'll take a look at the effects of variable cutter lengths.

When you first start sharpening your chain, it's natural to wonder where to start, i.e. which cutter do you choose to begin the process? Does it even matter? Well, yes it does! Find out more after the jump.

Many of those coming to the chainsaw maintenance and cross-cutting courses don't realise that it's important to start filing the correct cutter when sharpening as you must end up with all the cutters filed to the same angle and the same length. And the clue is in those last few words - they should all be the same length.

This means that you have to base the length of all the cutters on the shortest cutter; but why does it matter? Surely as long as the filing angles are correct, the length of the cutters is irrelevant? Errr, no.

The main problem with having the lengths all different is that it will cause the chainsaw to cut in a curve rather than a straight line. There is a very noticeable drift from the cutting line, and I've seen it referred to as a 'banana cut' on the ArbTalk forum just recently. This is a good description!

So, when we start to sharpen we must find the shortest cutter - but what if there's a longer cutter that has lots of damage? What if they're all the same length? What if you don't have a set of vernier calipers to hand to check? Let's deal with each of these in turn...

Damaged Cutters

In theory, as long as you only cut wood with your chain the cutters shouldn't get damaged. But life being what it is, sooner or later you'll cut through some timber only to see sparks coming out of it - then there's the sinking feeling that you've just found a nail, or part of a wire fence, in the middle of the wood. Maybe you touched the chain on the ground as you exited a cut, or maybe there was just lots of small bits of flint in the rough bark of an old Birch tree. Whatever it is, one day you'll end up with the leading edge (or working edge) of the cutter getting damaged.

The main thing is to file away all the signs of damage. Now in our example where there is a longer cutter which is damaged, it makes more sense to file this first of all and then check it's length against the [previously] shorter one. If it's still longer, then it'll need to be filed more; if it's now the shortest one, then this is the one you'll base the rest on.

Same Length

If all the cutters are the same length, and none are more damaged than any others, then you've got no worries - start anywhere!

No Vernier Gauges

For the utmost accuracy you can use vernier calipers - but there really is no need, unless you pride yourself on engineering tolerances that NASA would be proud of. Use the simple nut and bolt trick - one bolt, fitted with two nuts is all you need. Fit the head of the bolt between the working edge and loosely tighten the first nut up against the trailing edge of the cutter (use the second one to lock it in place). For more information, check out this post...The Nuts And Bolts Of Meaasuring.

Setting The Lengths

Once you have sorted out any damaged cutters, and you know which one is the shortest, make sure that it's sharpened correctly and then measure along where the side plate and top plate meet. Set your measuring apparatus to the required length and don't forget to mark it!!. I just use a permanent marker to colour in the top plate so I know when I've gone round the whole chain.

Try to get the cutters all the same - if you don't you'll find it more difficult to get accurate felling cuts, particularly when using the medium fell technique as the saw will drift of course as you cut around the back of the tree. You might also find that you suffer from more vibration when you use the chainsaw, as the chain reacts to the odd lengths.

In the next post we'll take a look at filing angles and the working edge.

Left Hook

There's a lot of criticism within the industry surrounding the ability of chainsaw operators to correctly sharpen their chains. It's not helped by those in the industry who persist in setting out the same old myths that have been around for years. If you want the best performance from your chain then it needs to sharpened correctly.

Incorrect sharpening of the chain can lead to varied problems, from slow cutting performance to a greatly increased chance of kickback. Knowing how your chain should be maintained is extremely important - yes, it's a drudge but it needs to be done.

Here on DriveLink, sharpening the chain was covered in the following posts:

1. Chain sharpening: part one.


2. Chain sharpening: part two.


3. Chain sharpening: part three.

So, let's try and take a closer look at some of the problems encountered when sharpening. Find out more after the jump...

First off, it's important then when using the file that we keep it flat and straight whilst filing. We also need to maintain the correct pressure to ensure that the correct side plate angle is maintained. Now, it's difficult to measure the side plate angle correctly, although Stihl have attempted to make things a little easier with the various markings on their depth gauge tool; instead, when I teach sharpening I tell the students to use the angle specified in the manufacturers literature as a guide to how much 'hook' their should be on the side plate. An angle of 85^o would suggest little hook, whereas an angle of 60^o would show a definite hook in the side plate of the cutter.

The picture here shows a chain where this hook is completely wrong - the cutter actually appears to lean backwards and there's no hook at all. There's two major reasons for this:

• the file used to sharpen the chain was too large;


• too little pressure on the file whilst sharpening caused the file to ride up.

If you suspect the file you used was too large, check it against the filing table for your particular chain. If you use Oregon chain, check out their maintenance and safety manual at the manual - it's full of really useful information.

But what if you used the correct file size? It's likely that the lack of hook on the cutter was due to the file riding up as you sharpened - you'll be able to see this if you look at the shape of the gullet (between the cutter and depth gauge). If there's a ridge starting to form then it's a sign that you should have used a little more pressure - get rid of this ridge before you continue sharpening.

There is another possibility, and that is that you did not hold the file correctly - if you used a file guide, it should rest on the cutter and the depth gauge.

Try to maintain an even pressure on the file - not too much and not too little. Too much pressure results in the opposite problem; i.e. too much hook as the side plate is being filed by a different part of the file, resulting in what is sometimes referred to as a 'birds-mouth'.

Next post we'll take a look at cutter lengths.

Guide Bars (Part2)...

In the last post we started looking at how to maintain the guide bar; in this post we'll take a closer look at some of the problems that you may come across with a guide bar. More after the jump...

The guide bar is subjected to a lot of stresses, both physical and heat, and a poorly maintained chain will only exacerbate the problems and speed up wear.

Stresses

The importance of ensuring the bar is properly lubricated cannot be over-emphasised - the chain itself could be travelling around the bar at speeds in the region of 24m/s (but could be up to 28m/s).

In old money, that's speeds in the order of 55mph. Metal against metal. You can probably begin to see why that chain oil is so important.

The heat that is generated from any friction of the chain running against the guide bar, can cause the bar to overheat and turn 'blue' at the edges (called "blueing" for fairly obvious reasons). The overheating changes the properties of the guide bar and can cause it to become brittle, resulting in signs of damage on the bar rails.

It's clear then that the oil must be allowed to lubricate the bar and chain, and for this to happen it's important to keep the small oil hole clear and the bar groove free of debris.

Naturally, the chain tension will have a bearing on the amount of friction generated, and a chain that is set too tight can also lead to overheating.

Wear

A chain that is set to tight will increase friction and also wear (particularly on the bearings for the sprockets). A chain that is too loose will also hasten the distinctive wear on the bar under the nose sprocket (as well as where the chain enters the guide bar by the drive sprocket); you can detect this wear by looking just behind the nose sprocket - if the bar appears to be 'waisted' then it's probably on it's way out. As this only occurs on the underside of the bar, you can even out the wear pattern by turning the bar over when you carry out your maintenance.

A blunt chain will also damage the guide bar, but this time the wear is caused by operator usage; as the chain becomes blunt, the operator tends to push down on the saw in order to force the saw through the wood. Instead of the saw feeding itself in to the wood, the action of pushing down on the saw forces the chain to sit at an angle and this in turn will wear away the inside of the bar rails (on the underside of the bar).

There's a quick way of checking for this type of wear, where the inside of the bar grooves have become worn to such an extent that the bar should be changed. Looking at the photo (upper right) you can see that placing a straight edge touching the bottom of the guide bar and the cutter, should leave a definite gap between the upper edge of the guide bar and the straight edge. This is how it should be. Note, you have got to make sure that the edge is pushing up against the side plate of a cutter for this to work.

In this photo to the left, you can hopefully see that that gap is not there when checking out the wear. Because the bar and chain are worn, the chain moves over when placing the ruler up against the cutter and that gap we had, just disappears. This is a sure sign that the bar needs to be changed.

But that's not all - the raised rails on which the chain runs can be burred over (looks like a very sharp wire edge) and these must be removed with a flat file - ideally putting a slight champfer on the outer edge to slow down the burrs from reforming. Do not run your finger down the edges - those burrs are sharp!

The nose sprocket also suffers from a stressful life and you should check the following:

• Ensure the nose sprocket turns!


• If your saw is a Husqvarna or Partner you may want to check the end of the guide bar and see if it needs greasing. Other makers may also put grease points for the nose sprocket so check yours - you'll see the rivets that hold the sprocket in-situ and off to one side will be a small hole. The Stihl bars tend to be sealed for life and therefore do not need to be greased.


• The teeth also wear, and instead of becoming dull and they wear down, they actually become very pointed. The teeth should have a slightly rounded point on them - if it's a sharp, triangular point then those teeth are worn too far.

The image at right shows how the teeth have worn down to a sharp point on this guide bar.

That's about it for this post, although there are a couple more things about the guide bar that I might just throw in to another post soon. Keep checking back as we venture through maintaining our chainsaws.

The Nuts & Bolts Of Measuring...

Let's take a quick break from chain sharpening - in the last post I mentioned using a nut and bolt to measure how long the cutter was - but tantalisingly didn't say how. Find out how after the jump...

Do you need an infinitely variable, highly adjustable, yet lightweight and small tool for measuring? And you want to pay no more than a few pence for it?.

I give you the humble nut and bolt, or to be more specific bolt and two nuts. This is such a simple idea, cheap and effective that it's wonder why anyone would do it any other way. Let's look at how it's done...

Once you've sharpened your first cutter, you need to make sure that all the remaining cutters are filed down to the same size. Naturally you could use a ruler, or calipers, but for nearly all my teaching I just use a nut and bolt - it's easy to carry out about and if you do lose it out in the woods then it's no big deal to replace it (not that I condone dropping bits of metal in the woods, you understand).

By placing the head of the bolt between the forward edge of the cutter top plate and the depth gauge, as shown in the picture, you can then gently screw one of the nuts up to the back edge of the top plate; left tlike this, the nut will move about as you measure the remaining cutters, so once you have set the first nut, tighten up the second nut to it. That way, it acts as a locknut and it will resist moving about as you work around the chain.

In the next post, we'll get back to sharpening the chain with a look at depth gauges.

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.

Name Your Chain...

Until now, I've tried to keep it as unconfusing as I can - but I'll forgive you if you lose it a bit on this one. It's not(?) hard, it's just that each manufacturer has it's own terminology and that leads to confusion.

So, let's take a look, after the jump, at what all these odd terms that we find on the filing tables mean...

Whilst we were looking at the Oregon filing table did you notice that they didn't refer to the cutter profiles using the same names as we used earlier? No? Look again.

Let's take a look at the list below to see our naming convention, along with Oregon's (in red) and Stihl's (in green):

• Chisel: Round Ground Chisel: Super


• Semi-chisel: Micro Chisel: Micro


• Chipper: Chipper: Standard

Stihl also refer to their cutters as normal height and low profile, for which they use the terms "Rapid" and "Micro" respectively.

Chain Sharpening: Part 1...

Sharpening your chain is one of those necessary evils that we all have to do in order to keep the chainsaw cutting efficiently, a dull, worn cutter is just not effective at getting through the wood and it'll tire you out, making life harder.

So, for an easy life with your chainsaw it's worth learning the art of sharpening the chain - it'll save you having to take the chain to your local garden machinery centre to have it sharpened and that means saving you money. How's that then, this site is already making your like easier and saving you money.

In order to sharpen your chain though, there's a few things that you need to know first - find out more after the jump.

To maintain your chain at it's most efficient and effective, you need to know something about your chain to find out the following details...

• What file size you should use.
• What filing angle you should be using.
• What the depth gauge setting should be (you do remember that the depth gauge on the cutter regulates how much wood gets cut don't you?)

To do this you have to know how to identify your chain, then you can set about finding the information you need. Let's take a look at chain ident.

Chain Identification

If you click on the image at the top left of this post, you'll see that the chain has some numbers on it (this particular chain is made by Oregon - one of the largest producers of after-market equipment for chainsaws).

The numbers appear on both the drive link and the cutter - or more specifically the depth gauge on the cutter. These numbers give us some clues to the chains identity - but be warned... Oregon, Stihl and Husqvarna all mark their chains differently, the numbers may be in the same place but the meanings differ. So here's your simple guide around the murky world of chain identification.

Oregon

Looking at that image again we can see that on the drive link is the number '18' and on the depth gauge, '50' appears. With Oregon chains the number appearing on the drive link is an I.D. number that you can cross-reference with a filing table.

The image above shows an Oregon filing table, these are pretty easy to use and your first step is to take a look down the left hand side and find the row which relates to the number of your chain.

Our particular example shows a number '18' chain - look down the bottom of the table and you'll find a row marked '18H*'; that's ours. Reading across the row, we find the following information (L-R):

• File size: 5.5mm round file.
• Depth gauge setting: 1.2mm (or 50 thou').
• Filing angle(1): we would need to hold the file 10^o down, while...
• Sharpening angle: ...pulling it back 35^o to ensure the correct cutting angle.
• Side plate angle: 85^o. Forget about this for a moment - we'll deal with this in a later post.
• Cutter profile: this is the profile of our chain - notice Oregon don't call it a chisel, semi-chisel or chipper; this is also true of Stihl. All you need to be sure of is that the profile matches the chain you are holding (you are wearing gloves whilst you hold that chain aren't you?).

But what if you have a #21 or #22 chain? Looking down the left hand column shows that there are two rows with these I.D. numbers - and the information within those rows is different. So how do you choose which one is yours? Easy - look over at the right hand side at the profile pictures, compare it to your cutter profile and whichever one matches is your row.

Stihl

Stihl do things differently, and the numbers on the chain refer to different things compared to Oregon (and Husqvarna). It's not better or worse, just different.

The number on the drive link of a Stihl chain relates to the gauge of that chain and you'll see one of the following:

1, 3, 5, 6, 8, 0

These figures relate to the normal gauge sizes of:

1.1, 1.3, 1.5, 1.6, 1.8, 2.0mm

The number on the cutter shows the pitch of the chain and will be listed as:

325, 3/8 or 404

We can use this pitch information to find the data we need for sharpening the chain; just search for all the chains with your pitch and refer to the chain type. We'll cover this in more detail in another post, as Stihl refer to their chains as Rapid, Picco, Super, Micro and Standard.

Husqvarna

Husqvarna have made it very easy. Just take a look at the number on the drive link, look down the Husqvarna filing table for the same number and there you have it.

Simple.

Next post... we'll take a look at the naming convention used by different manufacturers for their chain.

Related Posts:

[HD VIDEO]: Sharpening The Chain

Chain components...

The chain you use for sawing will be made up of just a few components - but those components have a bearing on what the chain will be best suited to, and how safe it is.

Although there are many different types of chain, made for particular applications such as rip-cutting, cross-cutting, metal cutting, chains (for the moment at least) can be divided in to standard chains and safety chains.

A standard chain has the following components:

• Cutter: this, as the name may suggest, cuts the timber - but it also regulates how much timber is cut.


• Tie-Strap and Rivets: these hold the components together and the chain gets its flexibility from the use of rivets, in the same way a bicycle chain does.


• Drive Link: this performs several functions as it transfers drive from the engine, cleans the guide bar groove as the chain rotates and carries the oil to lubricate the chain and bar. This link must match the bar in use as several different sizes of chain are available.

The components above form a standard chain, but there is an additional chain component that can add to the safety of this item by smoothing out the cutting action, reducing vibration (and therefore whitefinger) and reducing the chance of kickback. This component is called a Guard Link and is really a modified drive link. This link has a sloping top, and it's position in front of and alongside the cutter helps the lift the wood up to the cutting edge.

Cutters come in a variety of profiles, which are best suited to particular applications and each has it's own advantage and disadvantage.

• The chisel profile is good for use in softwoods and it has a fast cutting action to slice through the timbers. This cutter profile is prone to dulling quickly and is therefore less durable than other types of cutter.


• At the other end of the extreme is the chipper profile, which is ideal for hardwoods, but has a slower cutting action. However, the advantage of this cutter is that it is more durable than the other types - and that potentially means less sharpening :-)


• In between these two types is the semi-chisel profile - this is a good all-rounder balancing the speed of cut of the chisel, with the durability of the chipper.

Next post... pitch and gauge.