DIY Guide to Chainsaw Use

Petrol vs Electric
The obvious advantage of a petrol chainsaw is that is doesn't have a lead. Electric chainsaws are a LOT cheaper costing £50-£100 as opposed to £300 and counting. Electric chainsaws also cost less to run, are quieter, less 'scary' and good ones are just as powerful.

Use
A well-maintained chainsaw, used properly, cuts by itself. If you are cutting downwards, the weight of the saw alone should normally be enough to push through the cut -- you don't need to force it. If you need to push on the blade, or the blade tends to get stuck in the cut, something is wrong -- most likely the chain is blunt, or the cut is closing up around the chain (see below).

When you cut down with the underside of the bar, the saw will pull towards the workpiece If the work is fixed -- a stout tree branch, for example -- it will pull your arms towards the work. If the work is not securely mounted, the work will be pulled towards you. Even heavy logs can be pulled surprisingly forcefully towards the saw. The amount of pull will depend on the power of the saw and the throttle setting, among other things, but could be more than 50 pounds. You can avoid this effect by starting downward cuts with the body of the saw touching the work, and then cutting by rotating the bar downwards, rather than pushing the whole saw downwards. Of course, if the work is thick, you'll have to push downwards as well as rotating downwards. In any case, you should usually avoid cutting with the furthest third of the bar, because kickbacks are mostly likely if the tip of the bar snags on something. If you cut upwards with the top side of the bar, you'll get the opposite effect -- the saw is pushed away from the work. These push and pull effects are not necessarily a problem, but they can be surprisingly forceful, so it's as well to be aware of them.

Maintenance
Chainsaws use a lot of oil so check the level every hour or so. Depending on how the chain is secured it may loosen gradually over time and will need to be tightened to the correct tension shown below: A properly-adjusted chainsaw does not turn the chain at idle For safety reasons, a petrol chainsaw should be capable of being left ticking over between cuts. A properly-adjusted machine will not idle fast enough to engage the clutch and start the chain turning. The engine might idle too fast if the choke is open. This is why the instructions supplied with most chainsaws state that, when starting the machine cold, you should close the choke as soon as it seems that the engine will fire. A chainsaw whose chain moves when idling, with the choke fully closed, might need its idle screw adjusted. However, a common cause of this problem is an incorrect fuel-oil mix in two-stroke engines, so it's worth checking this before tinkering with the carburettor.

When replacing the chain, put it on the bar the right way round This seems obvious, but there's nothing to prevent you putting it on back-to-front, in which case it won't cut very well. The correct orientation will usually be marked pictorially on the machine somewhere near the bar.

Causes of Injury

• Kickback
• Slipping on a slope and bringing the chain down onto your legs.
• Bits of wood flying back into your face.
• Using a chainsaw on a ladder.

Petrol chainsaws are designed to cut at full throttle At full throttle a powerful chainsaw is extemely noisy and smokey, and you are likely to be tempted to regulate the speed (and the noise) with the throttle. Unfortunately a petrol chainsaw is not designed to operate this way, and it won't be efficient or safe. The blade needs to be spinning at full speed before it even touches the workpiece. If it isn't, it will either not cut at all -- because the clutch will disengage -- or it will snag.

Watch the chain tension When cutting continuously, the chain will get hotter than the chain bar, and expand more. This means that the chain tension will reduce. If the chain becomes too slack, it can jump off its sprocket, which often means that you'll need a new one. In any event, there will be a certain amount of downtime. If you adjust the chain tension when the chain is hot, you'll reduce the chain slack, but when the chain cools down it will bind on the bar, and not cut at all. Most manufacturers recommend adjusting the tension when cold, but this means that you'll need to keep an eye on the chain slack when the chain warms up, and either tweak it or let it cool down if the chain starts to hang off the bar. Needless to say, a chainsaw that offers tool-free tension adjustment will provide for easier tension control than one that requires a screwdriver. A new chain will stretch a bit, and therefore lose tension, in the first few minutes of use. Before cutting, consider whether pressure will develop on the bar during the cut Chainsaws are provided with a clutch, to prevent damage to the engine if the chain cannot cut. In general, if the chain becomes crushed between two pieces of wood, you won't be able to power out of it, nor will you be able to pull the saw out of the cut. Instead, you'll have to stop work while you insert wedges with a sledgehammer to free the blade. The problem is much worse on resinous woods, particular softwoods cut in the summer. All this means that, before you cut, you'll need to think about how the wood will move during the cut. For example, if you are cross-cutting (that is, sawing up) the trunk of a felled tree, and the trunk is propped at both ends on its branches, then if you cut downwards the weight of the tree will cause the cut to close up around the saw blade, and it will get trapped. Instead, if you cut upwards from below the trunk, the weight will tend to open up the cut, and it is less likely to trap the blade. On the other hand, if you are lopping a stout branch from a tree, the weight of the branch will open up the cut if you cut down from above. This creates another problem, of course -- as the cut progresses the weight of the branch will put tension on the remaining, uncut wood, which might tear. The solution is to make a small cut from below, and then cut down from above.

If you don't cut a hinge when felling a tree, try to cut in the direction of the tree's natural angle of fall It is standard practice to cut a hinge (a wedge-shaped cut-out) in the side of the trunk to control the direction of fall. Any chainsaw will be supplied with instructions showing how to do this. Where the trunk is less than about three inches in diameter at the base, it is not really practical to cut a hinge. It you don't cut a hinge, but instead cut across the trunk in one movement, then one of two things will happen. If you are cutting towards the tree's natural direction of fall, the tree will start to fall as soon as it's own weight is too heavy for the remaining wood to support. You might be left with a jagged stump, which can be avoided by making a shallow cut in the other side of the trunk before starting the main cut. If you cut against the tree's natural direction of fall, the tree will settle on the blade, and the cut will close up and jam the blade. If you're lucky, and strong, and the tree is not too heavy, you'll be able to put your shoulder against the trunk and push hard enough to open up the cut and pull the blade out. If not, you'll probably need winching gear to free the blade, which is a drag. The trickiest situation is where you have a sapling or coppice pole growing straight upwards, and there is no natural fall line. In that case, if you cut straight across, you'll either get the blade snagged, or the tree will fall in an unpredictable direction -- Sod's law says that it will usually fall on you. Even a three-inch diameter coppice pole is quite heavy if it's thirty feet high. You need to be sensitive to the pressure on the blade, and be prepared to change the direction of cut if the tree starts to settle on the blade.