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...

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.

Stihl Quick Tension System...

Maintaining the correct chain tension is rather important - too loose and the chain may derail, too tight and the saw will effectively lose power. Many saws require the operator to carry around a combi-spanner to adjust the tension, but a number of smaller saws are available fitted with a quick tension system. In this article, we'll have a look at them and see how they compare after the jump...

I mentioned above a couple of issues regarding chain tension, but there's more; a chain that's too loose will also not cut as effectively as a correctly tensioned chain. Why? Because as the cutters come in to contact with the wood they sit back slightly, and that results in the cutting angles changing. A loose chain will also wear quicker, as well as increasing the wear on the guide bar. Fortunately you can easily recognise a loose chain - either because it's hanging down from the underside of the bar, or because it revolves around the bar when the engine is at tickover (with idle speed adjusted correctly).

A chain that's too tight will result in the chainsaw using up some of it's power to overcome the friction and that's what results in the lack of apparent power and unwillingness to rev freely. That increase in friction can lead to overheating too. It also puts the bearings of the nose sprocket and drive sprocket under undue stress.

So, convinced of the need to get the correct tension, the easiest and fastest method would seem appropriate; but different saws use different systems. The standard method, shown on the right, uses an adjuster screw that can be accessed through the side panel (although some saws have the adjuster screw at the front, facing forward, next to the guide bar - these are really awkward to use, especially with a combi-spanner). Before we can set the tension, those two nuts holding the panel in place must be loosened first as they're also clamping the bar in position.

Maintaining the tension in this manner requires the user to carry around a combi-spanner (with a flat end, not a Torx-head end). The operator first loosens off the two nuts, sets the tension using the flat screwdriver, and then tightens up the two nuts. Job done.

Nowadays, many users (particularly home-users) don't want the aggravation of having to have the combi-spanner to hand in order to adjust the chain, and manufacturers set about finding an even quicker way of correcting the chain tension with the least amount of fiddling about.

Enter stage left... the quick tension system. The example in the photo here is off of a Stihl MS250C, but it's similar to many other fast tensioners. The photo at the top of the post shows it with the side panel still fitted. You can see on that photo the large 'dial' on the side - this is not the tensioner, but it's a quick release for the side panel. The actual bit that the operator uses is on the top of the side panel - a small black wheel that links in to the cog fitted to the guide bar (that can be seen on the photo to the left).

To adjust this system, all you need do is flick the handle out of the quick release dial, back it off a fraction, then use the adjustment wheel to set the tension and tighten up on the side panel. It is quick and it doesn't require any tools. But is it any good?

Personally, I found it a bit awkward to get the right tension and it's not as finely adjustable as the good old screwdriver adjuster. Having said that, it does work, but I'm not sure I'd want one on a professional saw; for the home- / occasional- user however it's probably ideal. It also means that changing the guide bar is not quite as quick either, as that big cog is bolted to it and should be removed before swapping bars - the other thing that it means is that when it comes to your regular servicing and you turn the bar over to even out wear... you need to take the cog off and swap it over too.

So, for now at least, it's the old way of doing things that wins it for me; not just for setting the tension but also for ease of maintenance.

Makita DCS4301 Review: Catch It If You Can.

Chain catchers. Vitally important in improving the safety of your chainsaw should something unexpected happen to the chain whilst you're using it. Different manufacturers do not create their chain catchers equally - even among their own offerings. So let's find out how Makita score on the DCS4301 after the jump...

Chain catchers are extremely simple devices and designed to take the energy out of the chain should it snap or derail. They are, in essence, consumable items and need to be easy to replace should something happen. Many of the home-user / farm-user level of saws have the chain catcher moulded in to the side plate, and this saw is no different. Of course, what it means is that should your chain demolish the chain catcher, you'll need to replace the complete side plate, rather than just the catcher itself.

The worst saw in this respect is my Husqvarna 350 - the chain catcher is actually moulded in to the main body of the saw! Not great.

Once you move in to the professional range of saws, things change - but at this level it's not unusual for the catcher to be integral with the side plate. Of course, you can help minimise the risks of something untoward happening to your saw by ensuring the tension is kept correct and ensuring the chain is being lubricated.

Drive Sprocket (Part 3)...

Now that we have mentioned the different types of sprocket (rim & spline, and spur), and also seen how to remove or replace the sprockets, it's time to take a closer look at how they wear. Just how do you decide when to replace them? More after the jump.

Drive sprockets have a hard life - they're constantly pushing the chain around the bar, they have the centrifugal clutch weights working on them and they have the chain brake band clamping the outside edge of the sprocket. All in all, they get it tough and it's no surprise that they don't last forever - in fact, you should be looking to replace your drive sprocket every 2 to 3 chains.

There are other ways of telling when the sprocket should be replaced. The teeth will wear down as they transfer drive to the chain by pushing the drive links along, the result is a groove that runs down the face of the tooth and wear on the top edge of the tooth caused by the tie-straps - when this wear reaches 0.5mm it's time for the sprocket to go (as shown in the image to the right).

The action of the clutch weights spinning out and contacting the inside of the sprocket will wear a grove in to metal, and it's not long before a slight lip appears on the inside. This is not normally a problem, but I have found that on Stihl saws, if you don't take the sprocket off for cleaning every now and then, the build of gunk and grime caused by sawdust and chain oil, can actually make removal of the sprocket very difficult.

Whilst mentioning Stihl, the other thing to watch out for are hairline cracks. I've noticed this on just a couple of sprockets in the past and they're caused by that little notch on the edge of the sprocket that drives the oil pump. I guess it's a weak point with the constant heating up and cooling down causing a stress fracture... eventually (if you don't catch it in time) it will break, as you can see from these photographs. Click on the images to see them full-size).

The chain brake operates on the outer edge of the sprocket and when used correctly created very little wear. However, many chainsaw users get in to the habit of revving the saw up, making their cut and then slamming the chain brake on - without waiting for the chain to come to a halt first. As well as greatly increasing the wear on the sprocket, the stresses involved in stopping a saw running at 12,000rpm to a dead halt in a matter of milliseconds does the chainsaw no good at all. Please wait for the chain to stop before putting the chain brake on! The wear can be seen as a series of grooves around the outer edge.

In fact, we'll take a closer look at the chain brake mechanism in a later post. But for now, you know what to look for on your drive sprocket.

Poor Cutting Performance...

Does your saw not cut as well as it used to - figure it'd be easier to use the old bow saw instead? Are you having to apply quite a bit of pressure to get the saw to cut through the wood? Do you find yourself actually performing a cutting motion as if you were using a normal hand-saw? Does the saw no longer cut straight?

All of these things are a sure sign that there's a problem with your chainsaw that needs sorting - and fortunately they are all to do with just one component on the saw. Find out more after the jump...

It's very common for users of a chainsaw to carry on trying to cut through the timber even though it's obvious that something is not quite right; hopefully after this post, you'll have a better idea of what to look for and how to correct the situation.

The saw should self-feed, that is to say that it should cut through the wood with very little pressure as the cutters will pull themselves through the timber - forcing it through the wood just increases wear and effective loses power due to the increase in friction. So if you are having to push down on the saw, or rock it back and forth you're going to have to face the fact that... it's blunt!

There's nothing for it, but to sharpen the chain. Trying to cut with a blunt chain is a lesson in futility - it takes longer, is more tiring to you and it's not good for the saw. Always use a sharp chain. There's one sure-fire way of telling if your chain is blunt and that is the wood-dust that is produced. This dust is just like a fine powder and really does give the game away.

A sharp saw should produce wood chips, but you must remember to ensure that the depth gauges are set correctly to maximise the amount of timber cut by each cutter.

Sometimes a chainsaw just will not cut in a straight line; this is a classic symptom of incorrect sharpening and caused by having the cutter lengths different. Remember, the length of the cutters must be the same for every cutter. You can check the lengths using the nut and bolt method as mentioned in an earlier post, and in the picture on the right.

A saw that suffers from a lot of vibration when cutting is likely to have the cutters incorrectly filed (i.e. set to the wrong angle) or the depth gauges set too low (i.e. filed too heavily). This last scenario is a particular problem as it increases the risk of kickback from the saw.

If your saw is not cutting efficiently then try to work out why; all of the above problems are related to one single chain compenent... the cutter, and that's where you should start your search for the reason behind poor cutting performance.

Creating Tension In A Video...

As promised in an earlier post, I thought I would try and create a short video about tensioning the chain, and here it is... after the jump...

Hopefully the following video will put across in a few short minutes what I was trying to get across on my earlier post.

Please, remember to wear gloves when you're handling the chain; lift the nose of the bar up when you adjust the tension; and tighten up those side plate nuts before you run the saw up!

Too Hot To Handle...

Just to finish off a couple of things about chain tensioning - things which many people forget to mention, but that have a huge impact on how loose, or tight, your chain is. Find out more after the jump...

If you have just adjusted your chain after carrying out some maintenance then your chain should be set correctly based on the information in the last post "Chain Tensioning...".

But what if you've just been cutting some timber and realised that the chain is a little loose? If you're not careful, this is where some of the problems can creep in.

Obviously, as you've been cutting a certain amount of heat is generated (that's one of those understatements - a lot of heat is generated!). As I'm sure you are aware, when something heats up it expands, then when it cools it contracts.

Now I'm pretty sure that you are ahead of me here - if you've been merrily cutting wood for the last ten minutes, that bar and chain will have heated up nicely and the chain will have expanded. That expansion makes the chain appear looser than it was when the saw was cold. And here is where the problems can occur.

If you were to adjust the chain tension whilst it was hot (quite apart from burning your hands whilst you held the bar nose up), you'd find that as it cooled down the chain would shrink and tighten up around the bar. The chain tension would now be way too tight.

To solve this problem, always let the chain and bar cool down first, before you adjust the tension - it's a good excuse to grab a cuppa while you wait.

Chain Tension...

If ever there was a subject about which produced lots of differing views, this has to be it. I've been told so many ways of how I should set the tension of a saw chain that I could write a book blog article about it.

Most of these ways are street-myth, complete rubbish or somewhere in between. Some have a certain amount of truth in them, whilst others belong in a Hans Christian Anderson tale.

So, for this post, we'll take a look at some of the ways of setting chain tension.

It should be easy really, just set the chain so that it's not too loose, and not too tight; somewhere between those two extremes is the correct tension. But where? Let's examine a few of the more popular methods of checking chain tension...

1. "You should be able to lift the top of the chain and see 1 / 2 / 3^* drive links." ^*Delete as necessary.

Nope. This just does not hold true - there are too many variables at play here to make this worth listening to. Your strength will have an obvious bearing on how much you can pull up on the chain; in fact, just how much force should you use when pulling up the chain? The length of the guide bar will have a huge bearing on how much you can pull up anyway.

2. "You should be able to fit a penny between the chain and bar."

No - complete rubbish! See above.

3. "You should be able to push the saw over the worktop and the chain should move round as the saw moves across the flat surface."

There's some truth in this one - but I have a major problem with it... how many nice flat surfaces are there out in the woods? However, this is one that I used to use to set the tension up in the workshop, and is similar to the next one...

4. "Grip the chain on the topside and underside of the bar; the chain should move round reasonably easily... now hold the chain on the topside of the bar and pull it towards you. The saw should move across the flat surface, but the chain should remain still."

This suffers from the same problem as the previous option - but for setting the tension in the workshop, it's pretty accurate. But no use in the field where flat, smooth surfaces are hard to come by.

So where does this leave us? Four different methods, two of which I would give some credence too (options 3 & 4), and two that don't deserve the time of day (options 1 & 2).

The simple answer is to set it in the workshop, get a feel for how tight it is and use that as your basis for future tensioning. It's a bit of a 'feel-thing' that you get with experience, but let's try to give you a better answer than "let your experience be your guide", as that's not particularly helpful if you are new to chainsaws!

First things first... take the chain brake off so the chain is free to move! You'd be amazed how many people forget that bit.

There are two very basic rules...

1. If you can see daylight between the underside of the guide bar and the chain, it's too loose.


2. If you can't move the chain around the bar, it's too tight.

Between these two extremes of tension is what we are after, so here's how to do it - in fact I might just make a video of this and post it up later...

1. Make sure the chain brake is off and that you are wearing suitable work gloves.


2. If necessary, slacken the nuts that are clamping the guide bar in place (or whatever system your saw uses to hold the side plate and bar on with). We don't need these really loose - just finger tight will do.


3. Slacken off the tension until the chain is obviously too loose.


4. Using one hand, hold the nose of the bar up.


5. Now, whilst the bar nose up, adjust the tension so that the chain just touches the underside of the bar. Adjust the tension just a little bit more, so that the chain fits snugly against the guide bar - no need to overdo it.


6. Whilst still holding the nose of the bar up, tighten up the side plate nuts / bolts / quick-release system.

That's it - you're done! There are a couple more points to note when tensioning your chain, but those will be mentioned in the next post.

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.

Guide Bars...

Maintaining the guide bar is not difficult, but in the past I've found that many chainsaw users neglect to check certain aspects of their guide bar. Find out more about maintaining your guide bar after the jump...

How to set about removing your guide bar will depend on the make and model of your chainsaw - but you will need to slacken off the chain tension a little and then remove the side plate. You should now be able to get the chain and bar off of the saw.

With the bar off, let's take a quick look at it; at one end there will be a slot cut in it to allow for adjustment when tensioning the chain and at the other end should be a sprocket around which the chain runs. There will also be at least one small hole down near the slot too - one of these is to allow the chain and bar to be lubricated with oil. As well as the makers name emblazened on the side of the bar, you might also find a laser-etched information panel showing you the pitch, gauge, bar length and number of drive links required for this bar.

When it comes to maintaining the bar, you should be looking out for a number of things:

• Is the bar straight?


• Does the sprocket at the end of the bar turn?


• Are the sprocket teeth worn?


• Are there signs of wear on the bar?


• Have burrs formed on the bar rails?


• Is there signs of overheating ("blueing" around the edges)?


• What condition are the bar rails in?


• Does the sprocket need greasing?

There are other things that we need to bear in mind, but lets have a look at a video that I made, showing guide bar maintenance before delving in to each area in more detail:

Hopefully the video gave you an idea of what you should be looking for, in the next post we'll take a closer look at the bar and exactly what to check for.

Oregon Maintenance Manual

Oregon, who are possibly one of the largest (if not the largest) suppliers of after-market chainsaw accessories also produce a useful booklet about their chains and general maintenance hints and tips. Find out more after the jump...

The booklet, which is available as a paper version can also be downloaded over the web as a PDF document (for which you will need Adobe Acrobat Reader). The booklet covers information about Oregon's own chains, detailing filing angles, file sizes, pitch and gauge information, as well as pictures of the chain profile. It also includes several pages of maintenance hints and tips and is worth taking a look at - I carry one around with me when training as it's quite a useful little reference and the paper version is a fairly compact little booklet.

OK, so it may not win any major book awards, but it's free and is a handy little guide to boot. Get your copy at http://www.oregonchain.co.uk/pdfs/MaintManual_English.pdf

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.

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

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).