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.