Stretched chain question...

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Mike Kunte

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Hi!
My BIL messaged me yesterday, saying that he could no longer tension his 84DL Stihl Carbide chain, since he'd run out of adjustment. He queried whether it was wise to take a link out of the chain to allow it to be used. Considering the cost of Carbide chain, I don't blame him. What is your take on shortening chains? Will the drive and nose sprockets be damaged? What is the best course of action? Please let me have your recommendations!

Thanks for your 2c !

Mike
 
Yes it can be done, although it is possible that it might turn out a bit short. chain stretching is 2 items one is wear ( possibly not enough oil) second is heat which goes along with shortage of oil. not taking tension off chain when through using also has some bearing on this.
 
Most likely the rivets are wearing in the chain. Put the chain on a bar, loose and push it together, and then pull it apart. You will SEE how much it has been stretched. I have known people who remove a link to run the chain and get a little more life out of it.
 
What is your take on shortening chains? Will the drive and nose sprockets be damaged?
Chain stretch is usually the wear of the rivets and/or rivet holes in the tie straps, Adding a few thousandths here and there, adds up to inches. At some point, you may run out of chain tension adjustment before you use up the cutter life. So taking out a link or 2, shortens the loop length, bringing you back into adjustment range. But you still have not addressed the wear issue.

Worn rivets/holes make the spacing of the drive links longer, essentially changing the pitch of the chain. While we measure pitch by the spacing of rivets, the real issue is the pitch of the chain matching the pitch of the drive and nose sprockets. If they don't match, the chain will not run right.
Chain Pitch.pngSTIHL Drive Sprocket and Chain.png

In normal use, the chain and sprockets wear together, developing a 'wear pattern', which is why manufacturers recommend alternating between a few chain loops at a time, rather than running them sequentially, and then replacing the drive sprocket and chains as a set. A worn sprocket will also be 'out of pitch' with a new chain.

Putting this together, running a chain with a link or 2 removed, to compensate for 'stretch', will cause faster sprocket wear on a new sprocket. But since the cost of a rim sprocket (under $10) or spur sprocket (under $20) is a lot less than the cost of a carbide chain ($!!!), it is not an unreasonable choice to make, if the chain runs without problems. Technically, a worn rivet will also be weaker, so the chain could break under heavy use, which is one of the reasons a manufacturer would likely not recommend this.

A hard nose bar would not have a nose sprocket to wear. If he only uses the carbide chain occasionally, he might want to use a separate drive sprocket and bar than the ones he runs with conventional chains.

Philbert
 
Make sure the rivets aren’t worn out. You should always run the shortest chain possible, which may be a link or two or three shorter than what the bar calls for. The bar heal should be as close to the drive sprocket as possible while still allowing the chain to be removed. A link should be removed ling before you max out the tensioner. This will prevent excessive bar wear at the heel and derailments.
 

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