chain trouble

[james]

friend has a husky 61 that keeps throwing the chain while bucking - new chain -new 20"bar    he says the chain is tight what should he look at  ??? ???
james

[Cut4fun]

Have had a few like this come to me.

1. Make sure new bar and chain are the same as the spur or rim being used. Like in 3/8, .325, etc. No mixing.

2.Then also I have seen a spur worn into 2 pieces and the same with a rim sprocket. Replace with same as bar and chain 3/8 or .325.

3. Make sure the chain and the bar are the same .325 or 3/8 and then the rim are the same 3/8 .325.

[Rocky_J]

Yup, the drive sprocket. So many replace the chain, some replace the bar, nobody ever looks at the sprocket. Then they wonder why it doesn't work right.  ???

Rule of thumb on tightening the chain- tighter isn't better- the rule is "No drag, no sag". Tight enough to not sag but loose enough that you can spin it easily by hand.

[sawguy21]

A worn sprocket can drive ya nuts. Tighten the chain, it binds. Loosen off so it moves it goes slack and jumps off the bar in full attack mode.

[rickywashere]

also take in account the experience of the operator some cant keep a chain on no matter what till they get time under there belt

[GASoline71]

Also when adjusting chain tension you have to lift up on the bar when doing so.  Keep lifting up while tightening down the bar nuts... If you don't the chain will become slack after only a few cuts...

Gary

[gemniii]

I was reading somewhere (Oregon site?) not to lift the bar for some type of sprocket nose bars.
Is this general practice?
Would this make enough of a diff for the chain to jump?
Also they recommend changing the sprocket every two chains.  I ASSume they mean after you've worn about two chains out  with proper sharpening.

With an inboard clutch (as on my JD CS62 and Efco MT3600) how do people check the sprocket?  Pull the clutch?
I know on my Stihl 021 it's easy to see.

[ErikC]

  I have sprocketnose bars on every saw, and always lift the bar when tightening up the nuts. Otherwise it turns out just like Gary said. Also I get many, many chains out of a sprocket, and it takes a lot of wear before they cause any problem for me.

[joe_indi]

The 61 like other Huskys  run bars having a groove width of 0.58" (1.5mm)
If your friend, by chance happens to use a 0.63" chain (1.6mm) in a Husky bar, the chain would be tight enough not to seat properly in the guidebar .

[Rocky_J]

Gemniii, I'm sorry but that is wrong, no matter where it was written. It's probably somebody's bright idea to compensate for homeowners who overtighten the chain by torquing down on the adjuster screw until it won't turn any more.

Just remember- "No sag, no drag".

Loosen the bar nuts 1/2-1 turn. With one hand, reach under the chain and lift up so the weight of the front of the saw is resting on your hand. Wear a glove if you are prone to cutting yourself on the chain. With the chain resting on your fingers, move your hand back and forth so you are sliding the chain back and forth on the bar. Watch the chain as you use your scrench with the other hand to tighten the tensioner screw. When it is tight enough that the saw moves instead of the chain, loosen it back up until the chain moves without sagging off the bar. When you have it correct, turn the scrench around and tighten the bar nuts without ever moving your other hand off the bar. Grab the bar tight enough to hold the saw steady as you tighten the nuts while you are still lifting on the bar.

[GASoline71]

Also... the Sprocket replacement "rule of thumb" is not wholly correct either.  They just wanna sell more sprockets... so tellin' you to replace them after 2 chains is BS.

Just look at the sprocket... if it has significant grooves in it from chain wear... then by all means replace it.  If that happens after only 2 chains... you're prolly runnin' your chain too tight.

Gary

[Al_Smith]

Further more if you are running a hard nosed bar which few do,it sets up differently .You leave about 1/4 of the length  of the driver below the bar .

Do not however run a hard nose on a saw with a wimpy oiler because they need bunchs of oil . Which eliminates most Stihls from being a cantidate .

[olyman]

Also when adjusting chain tension you have to lift up on the bar when doing so.  Keep lifting up while tightening down the bar nuts... If you don't the chain will become slack after only a few cuts...

Gary

x's many on this one. have told tons of chain saw owners---bout 1 out of ten listen!!! :

[beenthere]

GAS
Might be BS to you, but not to me. 

No different than not matching tires on duals of a truck. If they are different, they will wear one or the other (chain or sprocket) very quickly until they do match.

If chains are rocked and not just worn down gradually, then likely there isn't much sprocket wear to need changing. And as you say, it is only a rule of thumb.

I don't know how this rule of thumb applies to the rim sprockets.

[GASoline71]

It's the same...

I agree with the duals on a truck... been there... done that...

But to replace the sprocket (rim or drum) every 2 chains is not needed.  Chains that are the same guage as the sproket will wear in the same manner, no matter what chain is used.  Different brands... whatever.  I can go through quite a few chains before I will replace a sprocket... it's just a way for the manufacturer to sell more sprockets...

Do you think pro loggers are changing the sprockets every 2 chains?  Nope... that would be a lot of sprockets...

Gary

[John Mc]

Just look at the sprocket... if it has significant grooves in it from chain wear... then by all means replace it.  If that happens after only 2 chains... you're prolly runnin' your chain too tight.

Or running them too dull, which puts a more stress on sprockets as well.

[edwardj_]

I agree with most of the comments here...  I work at a shop that sells Stihl saws.  If the sprocket doesnt match the bar and chain or the chain doesnt match the bar then it will cause it to jump.  Have seen it on many saws.  The proper time to swap the sprocket if it is the proper one for the chain..  is when it is worn out.  chain life may be a little shorter once it starts to get close to worn out. but the 2 chain rule is BS.  we dont even follow that.

[paulpieter]

I don't cut that much but I having organised a number of chainsaw safety courses for our community and I attended all of them and do listen good. My take was that hard-nosed bar requires no-drag tightness. For sprocket-nosed bars chain tightness is much less an issue and can be tight enough even with some drag, especially if the bar is cold. It will stretch enough as it warms in work.

About replacing the drive sprocket, if my experience in many years as a teenage cyclist counts, If I didn't properly oil my chain, it would wear and stretch so much that over time, the chain would ride over the teeth of the sprocket. A new chain would work fine even on the old sprocket, although the teeth became worn with a slope on the leading edge. Probably wasn't good even for the new chain.

So I figure that the drive sprocket doesn't need to be replaced that often.