Ok, there's this chain, right? It's got cutting teeth on it. The chain runs around a bar with a groove in it. Because it would be a very bad thing if the chain came off.
It's powered by a two-stroke gasoline engine. The clutch works on a centrifuge. When it's at low speeds, it spins by itself, but speed it up and it spreads outwards and engages a gear running the chain, creating wood chomping power!
Kinda like this if it had teeth.
Or this if it had a handle.
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Anyhow, the engine is usually around 3 horsepower, and runs off an oil/gasoline mix. Usually start it up with a pull starter, although I have heard rumours, quite unconfirmed, of chainsaws with an ignition.
It'll be air cooled, which cuts down on the weight quite a deal. After all, you have to lug this thing around.
They'll have some kind of lubrication, so that the chain won't suddenly seize up. Ouroboros tells me that some smaller ones use the oil/gas mix to lubricate it, whereas others that I've seen have a separate lubrication for the chain.
These things are, as you can probably guess, quite dangerous. In the United States alone, (the only place where I could find any stats), there are over 40,000 injuries on a yearly basis due to chainsaws.
They're designed to tear through wood with ease, so they won't have much of a problem cruising through your flesh and bone.
They can often kick back at you, where you'll be cutting and the blade will suddenly jump back at you, towards your face. This will happen if the blade gets pinched between whatever you're cutting, or if you're using the tip of the blade. It can also happen when you use the top of the blade to cut. Always push down with the blade, don't pull up towards you. Don't use the tip of the blade.
Most of them will have some sort of an emergency shut off, for kickbacks. This is usually called the "blade choke" or "inertial choke". When the blade gets kicked back, the part that you're holding it by will stay in the same position, as the saw itself comes up. If it comes far enough, the saw will stop, to try n' prevent your pretty face being torn up.
They'll also have a kill switch, usually red. You need to hold down this button for the blade to move. If you let go of it, the blade gets stopped immediately, thanks to the chain brake. Try not to do this too often, as I'm sure it's hard on the parts. Just try and keep in situations where you don't need to stop the blade suddenly!
Wear chainsaw pants, made out of kevlar or ballistic nylon. Stopping fast moving stuff going through your flesh is a good thing. Ditto for goggles and eyes. Also, a helmet is good. caknuck tells me of one guy he know who got a chainsaw to the head and is only alive because of his helmet. Not really surprising, since that's what they're designed for. Steel toes shoes are also key, honestly people you should be wearing them anytime you're doing any type of manual labour.
Anyways, always cut facing away from other people, ideally you'd want them to the side. If they're behind you, they might get hit by wood chips. Keep your legs spread, and try not to cut yourself up.
Actually, don't listen to me. If you actually need to use a chainsaw on any semi regular basis, take an actual safety course. Trust me.
The first chainsaw, or "osteotome" as it was called at the time, was invented by an unknown German maker of prosthetic limbs, around 1830.
Of course, it was quite primitive, and wasn't exactly widely distributed. Various major manufacturers claim to have invented the chainsaw around 1920, but they lie. But at least those were designed to cut down trees.
In paticular, a German mechanical engineer (again with the Germans!) named Andreas Stihl patented a "Cutoff Chain Saw for Electric Power" in 1926, and a gasoline powered version in 1929. He had the first patents for a mobile, motorized chain saw designed for the cutting of wood.
Some major manufacturers of chainsaws include Stihl, Husqvarna, Makita and Poulan. Or so caknuck tells me.
Anyways, they're used for a number of things. Mostly cutting wood.
Ok, often people use them in the carving of wooden sculptures. You may also remember Bill Murray using one for an ice carving competition in the movie Groundhog Day. God I loved that movie. And then of course, what's a Massacre without Chainsaws?
And on that note, since the node that was here before got nuked, chainsaws are often weapons in various 1st and 3rd person shooters. Think DOOM. They're fairly powerful, but of course, have little range. But damn, they can be fun. As was shown to us by the Columbians in the movie Scarface.