Chainsaws : Correct Chain Tension

Alright today on Repairs101 Iím going to show you how to set up proper chain tension
on your chainsaw. For almost ten years I made my living working
behind a chainsaw. And, well this is one of them. Iím quite partial to the Stihls. I
do recognize that Husqvarna and Sachs-Dolmar and Echo all make excellent products ñ many
other manufacturers do as well. Iím just accustomed to and therefore partial to the
Stihls. I find them exceptionally tough. Exceptionally reliable. And, this one here is a thirty-eight
super-pro that Iíve had for twenty years or thereabouts and it still pulls like a Saint
Bernard going after a squirrel. I always keep my saws disassembled so weíll
just pop the cover off and put the bar back on. OK the first thing Iíll show you is you
might as well clean it up while youíre in here. If youíve got compressed air thatís
going to be the best thing obviously but if youíre out in the woods or up a tree or something,
youíre not going to have compressed air. So have a rag handy and try to get any big
chunks away from the sprocket, here, because if they get caught in between the chain and
the sprocket itís going to affect your chain tension. Eventually it will destroy it or
it will throw it out and then the chain tension will be lost. So just clean it up. OK now
something in particular you want to focus on cleaning is the chain adjusting screw right
here. If youíre out in the bush youíre probably just going to have ñ and just dig at it very
roughly and crudely but of course in the shop you should be able to have something a little
more elegant. I like to use my ex-girlfriendís toothbrush for jobs like this. There you go.
Get that nice and clean. And weíre ready to put the bar on.
OK so people call this the blade but of course itís not a blade itís called a bar. And
the bar has no top, no bottom. Youíll find that one side will wear out. When it does,
all you need to doÖ there you go. All you need to do is grab a flat file ñ you want
to hold it in your vise. And just cut off the high edges with your flat file.
Alright so the next thing is to get your chain on. Itís not a bad idea, by the way, to grease
the roller tip, OK, the sprocket on the end. And the idea is make sure you get your chain
on the right way. Now, whether youíve got chisel chain or chipper chain of course they
pull forward ñ that is away from your body ñ on top. You know itís going to be rotating
that way. OK now once youíve determined which way your
chain is going to go on, put it on the bar and bring the bar up to the mounting studs
and then just swing the chain overtop of the sprocket like that.
Hereís the adjusting screw and hereís the adjusting pin. Now Iíll just leave my finger
there and you can see it tracking back and forth. This screw is moving this pin right
here ñ currently Iím going forward and going forward will be pushing the chainsawís bar
out and therefore increasing the tension on it.
The next thing to show you would be these holes right here on the bar ñ one on either
side. OK and what they do is ride on that pin. So we just keep the chain in the barís
groove. OK it doesnít matter how slack it hangs. And then you just want to mount it
like that, get the chain all in underneath. Now you can see that Iíve left just a ton
of slack here and what weíll do is get the cover back on real quick and then take the
slack out using that adjusting screw. OK now Iíve just seated these very, very loosely
and as you can see the chain is way too loose here. So weíre just going to turn it this
way to gain access to the adjusting screw. And then, one of the critical things I learned
was that itís very important to hold the nose of the bar up when youíre making the
adjustment and when youíre doing the final tightening. As I turn this screw up the chain
tension comes out of the chain.
OK. Now you can see itís getting very, very close. Pull down on it a little bit and thereís
quite a bit of teeth still showingÖ so Iím going to pull up on it some more and now although
I can expose some teeth ñ and it looks like if I pull real hard I can expose perhaps three
to perhaps five. It snaps back nice and at the same time the chain runs really smoothly.
So I know Iím good to tighten this up and Iíve got correct chain tension.
OK so itís very important that you only pull the chain towards yourself on the top like
that and itís a good idea to wear a glove or have a rag on your hand or something like
that so that you donít get cut. But never ever try and pull the chain in the other directon
OK because youíre going to cut yourself on the chisels. Now thereís no question that
itís going to loosen up after youíve run it for a bit, OK. The chain is going to heat
and expand and the chain will loosen up a little bit. So it is a little on the snug
side. Trust me. Thatís what you want. Is it just a little on the snug side and yet
still free running like that. OK I have no problem rotating it with your hand but at
the same time you canít pull very much out of it and when you leave it cold ñ now Iím
talking cold before youíve used the saw at all: you do not want to see any slack hanging
here OK? Itís just not safe having slack like that on the chain.
I can tell you with authority that this is properly adjusted.