What did I do wrong?

[pyper]

I was cutting some hedges and the chain came off the bar (Stihl ms311). I had only been cutting 10 or so minutes, and I had tightened the chain just before I started. What did I do wrong?

The back of the chain got kind of torn up by the sprocket. I'm assuming this chain is no good now, correct?

 

[smokinj]

Sounds like the chain got bound up or pinched.

 

[Adios Pantalones]

Chain could have been caught, may have had it a bit off the gear when tightened, may not have tightened down the bolts after adjusting tension.

 

[Thistle]

Check it over very carefully - teeth,drive links,everything.Especially the bottom of links which go in the bar groove.There will probably be burrs on at least a few of them that will need to be filed off.Also those chain catcher metal plates that are on both sides of the bar in front of sprocket will need looked at for any flaws.Once chain is back on the bar,turn it by hand to see if there's any rubbing,if there's still burrs,the chain wont seat properly.

 

[WhitePine]

Did you recheck the tension after you tightened things? I always do. It helps catch screw ups on my part. Not that they happen all that often.

 

[pyper]

I did check the tension after I tightened down the bolts.

The underside of the chain is chewed up for six or eight inches. Some of the bottoms of the teeth have a new profile, and some are bent over and so forth. Fortunately, the drive sprocket appears unharmed. Must be really tough steel!

 

[Danno77]

wasn't a new chain was it? if so are you sure it was the right chain?

 

[Adios Pantalones]

My last chain stretch seemingly forever. It was hanging loose a couple of times- I was surprised it didn't skip the bar.

 

[pyper]

wasn't a new chain was it? if so are you sure it was the right chain?

It's the chain the Stihl dealer installed when I bought the saw. I never checked it myself, but they seem to know what they're doing.

It's been used some, but it wasn't really worn out. I'm not too sad to need to replace it though, because I had hit a piece of wire embedded in a tree (part of an old clothes line) and I wasn't able to sharpen so it would cut as well as it had.

 

[kevin j]

if it is a short bar and cutting in small branches, they are prone to throw off. Did it do it when you first contacted the hedge wood? Small branches say an inch or less put side loads on the chain especially if you are moving around or at an angle when it makes contact with the branch. Ideally, the bar should hold the chain on, but I know the smaller the bar and branches, the more prone to throw. keep the chain properly tightened and approach the branches squarely.

on the good side, a small bar means cheap chain and maybe past fixing. Or you can flat file the burrs off and keep it for a junk chain for landscape timbers, pallets, etc. I would pitch it and start over.

 

[pyper]

Hi Kevin,

I sounds like you've got it figured. It was a 20" bar, and the branch was about 1.5" and I was cutting into it at an angle. It was also leaning, so I can see how it could have some leverage. I'll avoid stuff like that in the future!

Thanks everyone! Hopefully I'll get a new chain tomorrow, and my next project is a big block of pecan that needs to be removed.

 

[kevin j]

I was thinking 12 to 14 inch bar, but I think you have the idea. Many different possible causes, not saying the only one, but I have lots of issues motorcycle trail clearing with a 12 inch top handle Echo pack saw. Have to run it pretty tight and use a good hand.