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.

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?