Stretched Chains

[czyhorse]

First forgive me if this is another fighting topic. I am really after knowledge.

before I got as into this on the level I am now..... I used to have the local hardware guy shorten my stretched chains by removing a drive link. Now that I know what I know, that does no seem kosher. Doesn’t that really throw things off, geometry wise, no matter what kind of sprocket system you are running? I am thinking my stretched chains should just be tossed. Am I wrong? Why?

on a positive note I figured the stretching was probably due to me over tensioning my chains. I have backed off a lot on the tension and the stretching is not such a thing.

 

[RED-85-Z51]

Stretched chains are touchy...im wary of rivet wear and weakening, if i get a chain that starts at the middle of the tensioner i might take a link out.

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[czyhorse]

Stretched chains are touchy...im wary of rivet wear and weakening, if i get a chain that starts at the middle of the tensioner i might take a link out.

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But if you are supposed to have 72 drive links and now you are running 71 is that going to chew things up cuz your timing is way off?

 

[RED-85-Z51]

But if you are supposed to have 72 drive links and now you are running 71 is that going to chew things up cuz your timing is way off?

No sir.

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[foeke]

It has nothing to do with your timing. Only the sprocket might wear out quicker.

 

[HarleyT]

The need to shorten the chain is also partly due to the deep wear in the sprocket teeth. Just change the chains and sprockets at the same time. Do not run the old chains on a new sprocket, it will damage it quickly.

 

[HumBurner]

Stretched chains are touchy...im wary of rivet wear and weakening, if i get a chain that starts at the middle of the tensioner i might take a link out.

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I've had a new chain come flying off the bar, spinning, when a link snapped hitting a 1/8" fir branch. Thankfully my swamper was 90* to the saw and 20' away or it may have caught him.

Haven't had a link-removed or peened up chain break like that before.

Anomalies? Probably. My experience? Yes.

 

[SteveSr]

First forgive me if this is another fighting topic. I am really after knowledge.

before I got as into this on the level I am now..... I used to have the local hardware guy shorten my stretched chains by removing a drive link. Now that I know what I know, that does no seem kosher. Doesn’t that really throw things off, geometry wise, no matter what kind of sprocket system you are running? I am thinking my stretched chains should just be tossed. Am I wrong? Why?

on a positive note I figured the stretching was probably due to me over tensioning my chains. I have backed off a lot on the tension and the stretching is not such a thing.

Chains don't stretch, they WEAR! Wear is caused by insufficient oil to lubricate the chain and flush out dirt and high loading. Forcing a dull chain to make it cut will cause high loading and only make this worse. A chain may also get "longer" due to thermal expansion of materials but this should go away when it cools back off. If it is getting hot your chain is probably dull. If you see smoke you have a real problem! Chain tension is usually not the boogeyman here unless you are way over doing it.

As others have said the sprocket and chain pitch has got to match to minimize wear on both components. A worn chain can wear out a new sprocket in short order... and vice versa. The object is to share the chain load over several sprocket teeth. This won't happen if the chain is worn and can also lead to the drive links being "peened" due to having to carry load on a single drive link.

I don't know if saw chains have any specific wear limits but on bicycle chains the normal discard point for a drive chain is wear of .062"-.125" over one foot length. In this case chains are MUCH less expensive to replace than chain rings and cassettes.

 

[Philbert]

Bicycle chains and bicycle sprockets used to last the life of the bicycle. Until they went to all that lightweight, alloy, and thin side plate stuff for racers (and wannabes).

Chainsaw chains don’t technically ‘stretch’, but the rivets and rivet holes wear. A few thousandths here, a few thousandths there, and pretty soon we are taking about fractions of an inch.

Then, the drive links don’t line up exactly with the drive sprocket OR the nose sprocket on the guide bar, so stuff starts to wear.

Taking out a link helps with a loop worn beyond the limits of the chain tensioner, but does not address the sprocket wear.

A lot of guys still do this. Just understand the trade offs. Rim sprockets are cheaper than a new chain. Solid nose bars have no sprocket. But chains running rough, or jumping off the bar, are other issues

Philbert

 

[HarleyT]

The holes that the rivets reside in get wore/wallowed out, and you can see it by laying the chain on a table, or rest it in the bar groove, and push a length of chain together, then pull the same length apart, and the difference in length of a worn chain is noticeable.

 

[old CB]

Back when I ran the early McCulloch saws with manual oilers, maybe I had a lazy thumb but I usually had to remove a link from each chain at some point. Since auto oiling came about, I've not had to shorten a chain. In fact, if I see the chain loosening and needing adjustment beyond a minimal amount, that says the chain is not getting enough oil. Also, like others have said, if you're running a dull chain and forcing it through wood, you're gonna put unnecessary wear on the chain (and sprocket).

 

[Wood Doctor]

I would never knock out a drive link on a stretched chain and shorten it unless I could no longer tighten the chain with the saw's chain tensioner and it thus ran too loose. Simple as that. Occasionally that is necessary, but not often.

 

[thomasinvancouver]

I usually get a drive link less than the bar specifies. The closer together the sprocket and bar heel are the less the bar heel will wear.

Everything else I had to say has been said.

 

[HarleyT]

Everything else I had to say has been said.

Huh?

 

[Philbert]

I usually get a drive link less than the bar specifies

‘Chain stretch’ is more of a problem with longer chains: the small amounts add up.

On some smaller saws you can’t physically fit a smaller chain loop. E.g. standard 56 DL .325 pitch chain will not fit on a 57 DL ECHO bar for love or money.

Philbert

 

[Pioneer]

The teeth on mine get too short before the chain gets too long. I gauge the setup of the bar and chain by how hot it runs. If the bar's too hot to touch after an extended cut then something's wrong. Even in dry hardwood that shouldn't happen, at least in comfortable ambient temperatures when you want to be out cutting. A dull chain, not enough oil, or an over tight chain all contribute to an overheated bar and accelerated wear of the bar and chain. Even non-adjusted depth guides can cause overheating because they make you push too hard in the cut.

Good oil flow is essential, if it's adjustable I turn mine up to where I'm satisfied with it. On non-adjustable oilers if I don't think it's flowing enough, I will use thinner oil, the amount of oil you're getting on a bar is more important than the type.
If you're scorching the paint off the edge of your bar something's really wrong.
Accelerated link wear that can't be avoided is when you're cutting in dirt embedded wood. In that situation you just have to put up with replacing your chains more often. That goes for your bar and sprockets as well.

 

[Harmon]

To my recollection I have never run out of adjustment on the tensioner before I have run out of teeth to sharpen... but for fun we used to give the new guy a loop of 83 drivers (3/8 0.050) which will almost fit an 036/361 w 25" bar. almost.