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.

Check out the Sawpod...

What's a Sawpod I hear you ask? It's a great way of carrying around your pruning saw (for those occasions when you don't need a chainsaw), it's light, easy to use and it works! Find out more after the jump...

If you tend to use a small pruning saw for tending to your trees, hedges or orchards then you really should take a look at the Sawpod.

I've been using one for about a year and when tree-climbing it's a neat solution and means that the saw is always ready to use. But it's better than just a cool place to store a saw, as one of the problems when climbing is that to hang your saw off of your harness with a karabiner means that the scabbard is always moving around.

And that's a problem because when you've got one hand on the saw, one hand holding on for dear life steadying yourself, you then need a third hand to hold the scabbard so that you can put the saw away. With the Sawpod it ceases to be an issue - you just reach down to your lower leg and slide the pruning saw away.

It fits on really easy, using Velcro fastening means that it will fit everyone and is fully adjustable. It's also designed to fit most pruning saws, for example I use my Sawpod with a Silky saw, but it readily fits other saws that have a scabbard too.

The only issue I found with it was that my ropes sometimes hooked around the handle of my saw, but that's a very minor gripe and probably more to do with my climbing technique than any design flaw!

If you need a method of holding a pruning saw, whether it's on terra-firma (more firmer, less terror) or up in the air, the Sawpod is well worth a closer look.

For more information, check out http://www.sawpod.co.uk.

Bath & West Show

The Bath & West Show at Shepton Mallet (UK) is on next week from Wednesday 27th to Saturday 31st May. It really is a great day out for the family and it's huge! There's so much to see - from horse riding to steam engines, clothes to drill bits. And I'll be there...

I'll be at the showground for the duration of the event (all four days), so if you are planning a day out at the show, please pop by and say "Hello!".

If you want to know a bit more about chainsaw maintenance, crosscutting, or felling techniques then stop by the Sparsholt College stand in the Woodlands Area and have a chat.

If you're going - I look forward to seeing you!

David.

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.

Another Useful Oregon Tool...

Oregon strike again with a really useful tool on their website that enables you to find out the correct chain for your saw. Find out more about this tool after the jump...

The 'Oregon Selector Guide' is a useful tool to ensure that you end up with the right Oregon chain for your chainsaw; you'll need to know some basic details, such as...

• Make and model of your saw.


• Length of your guide bar.


• The pitch and gauge of your chain.

By way of example, go to http://www.oregonchain.co.uk/selguide/selguide.shtm and select the following...

• Stihl, MS260.


• 15" guide bar.


• Pitch 0.325" and 1.6mm gauge.

Out of that you'll get a couple of choices of chain (Oregon #22, chisel cutter or semi-chisel cutter); but you also get a couple of other useful bits to go with it (the length of the chain defined as the number of drive links, number of drive sprocket teeth and their recommended bar).

I did try putting in the information about my Husqvarna 350 chainsaw, but it didn't come up with anything - guess I'll just have to go back to making my own chain up for that!

Anyway, it's a potentially useful little tool to know about if you need to find a chain for your saw, and it's at http://www.oregonchain.co.uk/selguide/selguide.shtm.

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

Safety Manual...

Your safety is paramount here at DriveLink HQ, and if you've bought a chainsaw (or borrowed one from a mate), read on...

So, you've just borrowed a mate's 25 year old chainsaw, you've got your shorts and T-shirt on and you're about to drop start the saw - but hold on just one moment.

Your friend did give you the safety manual with that saw didn't they? No? Well, you're in luck because Stihl make available their chainsaw safety manual and it's worth a flick through.

Most people that work in the industry know someone that's been got by a chainsaw and, as a trainer, I'm really aware that inexperienced users are at a greater risk... or are they>

The problem with being an experienced chainsaw operator is that you get complacent, work too fast, start to cut corners.

So whether you are a newbie to a chainsaw, or worked with saws over a number of years, take a few moments to go back over some of the safety aspects of using that wand of doom.

Safety Manual [PDF].

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).

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.

Chainsaw Safety Features...

All modern saws come with a series of features designed to make it safer and more comfortable to use. We'll take a look at them now - there are ten common features and several optional extras that make the saw more user-friendly.

Read more about these safety features after the jump.

These ten features are listed below, some are perhaps more important than others, and some are a legal requirement...

1. Chain brake (manual / inertia) / left hand guard. This is really important - make sure that it works before you start to use your saw. The chain brake operates manually, but also reacts to the saw if it should kick back.


2. Chain catcher. This small piece of plastic or soft metal sits close to the guide bar and chain under the side plate; if the chain should snap, or derail, the chain catcher takes the energy out of the chain, thus making it safer for you.


3. On / off switch. Note which way the switch works to turn the saw off - they're not all the same - even the same manufacturer may use a different switch on different models. Stihl are pretty consistent about theirs - you need to move it upwards to switch off (which seems the wrong way round for me), but Husqvarna have changed from moving it the right to moving it downwards (which makes more sense).


4. Safety throttle. Also known as a "Dead Man's Handle", but in these politically correct days that would be being 'dead-ist', so it's now a 'safety throttle'. Anyway, you need to press the lever in to operate the throttle.


5. Rear hand guard. Used to protect your right hand, but also useful for stabilising the saw when you start it on the ground.


6. Anti-vibration (AV) mounts. Fitted to saws to reduce the amount of vibration, which in turn reduces the chance of getting 'whitefinger' (Hand-Arm Vibration Syndrome).


7. Exhaust. Directs fumes away from the operator (unless the wind is blowing in your face).


8. Scabbard (chain guard / 'condom'). This protects the chain, you and anything near the sharp end from getting damaged.


9. Safety stickers. All saws must have safety stickers - it's a legal requirement here in the UK and they should warn you about the chance of kickback as well as pointing out that you really should have read the manual and be wearing proper protective equipment - they don't yet make chainsaw protective flip-flops and shorts.


10. Chain type - bit odd this one, as it's the sharp pointy end, but the type of chain used can make it safer. More, lots more, on this one later.

There are a number of 'optional' features too - decompression switches allow the user to turn the engine over easier when starting (but not as simple as the Stihl EasyStart system - that's so easy that a child of six could start the chainsaw. Hang on a moment, why would you want...). Manual oilers can supply the chain with more oil when cutting hard timber and heated handles will keep the blood flowing in your hands on the coldest of days (and if the blood is flowing that also will tend to reduce the chance of whitefinger).

I'm still waiting for the following optional extras: CD/radio, sunroof and air conditioning on my chainsaw.

Next post... what components make up a chain?