Rim sprocket blew up!!

[hamradio]

Today, while doing some light cutting, a friend's 044 seemed like the chain jumped the sprocket. I wasn't cutting with it, but I had been previously. He switched to his MS210 while I pulled the bar cover off to see what happened. I knew he had a rim sprocket previously (STIHL sprocket, not oregon). The rim sprocket was missing, but the E clip and washer were still there. The only conclusion I could some to was that the rim sprocket blew up. He's had the saw about 10 years, maybe 15. He's run a lot of chains through it (a lot of firewood cutting). I asked him if he ever replaced his sprocket, and he said no. I told him he was supposed to replace his sprocket every (as the manual says) however many chains, and he laughed. There were deep wear marks in the clutch drum where the rim sprocket sits, from it being so worn out (drivers hitting it). Can they blow up if you don't replace them? It seemed like that one did. I dug around in the leaves for a while where it had gone wrong, and couldn't find anything. It had to have blown up to come off. Is this common?

 

[RaisedByWolves]

Common?


I wouldnt think so, but its surely possable.



I recently had a saw given to me whos owner told me that the saw "Exploded" and wouldnt make the chain go roundyround anymore.


It was a nice saw and I threw it in the back of the truck without a second thought figuring it was a decent parts saw.

Few days later I put it on the bench to work on it and discovered this piece of metal hung up in the clutch cover and realized that it was the clutchbell that had been worn through and let the clutch out of its cage.


That was the "Explosion", all three clutch shoes and springs going their seperate ways.


Fools lucky he didnt get hurt.

 

[woodfarmer]

had one go on an 038 into 4 pieces

 

[Bermie]

If your friend had the same rim on the saw for 10-15 years, it's no wonder it disappeared. That thing was in all probability worn down to the very last shreds of metal and just finally disintegrated!!
I'd say it imploded rather than 'blew up', metal on metal for 15 years, friction, heat, stress, metal fatigue...do the math!
It would be interesting to see the condition of his chains too, drivelinks and all would probably be an unusual shape!

 

[pioneerman]

I got a Farmsaw ll from a guy who complained that the saw had internal rattling, and he figured it was ready to fly apart or have expensive repairs. Brought it home, checked it out and found that about half of the rim sprocket was missing. Replaced the rim, and saw is still working fine 3 years later.

 

[Lakeside53]

Sure they do... the chain tangs will eventually cut through them. What most don't realize is that a worm rim/sprocket is beating the crap out of the chains. It's false economy to run a worm sprocket/rim, especially a $4 - $6 rim..

The maximum wear is SUPPOSED to be 0.5mm (20 thou.).

 

[SawTroll]

I change the rims every two chains or so, as recommended by Oregon.

As Lakeside said, they are really cheap, but Stihl ones are of course more expensive than Oregon.

:deadhorse:

 

[Lakeside53]

I change the rims every two chains or so, as recommended by Oregon.

As Lakeside said, they are really cheap, but Stihl ones are of course more expensive than Oregon.

:deadhorse:

Yes, but we change ours every three chains:hmm3grin2orange:

 

[SawTroll]

:hmm3grin2orange: :hmm3grin2orange: - but I haven't notised any difference in wear resistance beetween Oregon and Stihl rims....

 

[Lakeside53]

:hmm3grin2orange: :hmm3grin2orange: - but I haven't notised any difference in wear resistance beetween Oregon and Stihl rims....

That's 'cos you are using soft oregon chains

 

[SawTroll]

That's 'cos you are using soft oregon chains

Not on the MS361, RSC and occationally RM.

Sprockets are a mix of Stihl and Oregon.....

 

[smokechase II]

well done hamradio

Way to go. You use the old run a sprocket well beyond its useful life to get a Stihl vs Husky supplier argument going.

 

[aggiewoodbutchr]

When I got my 084, it had a rim sprocket on it that was missing about 40% of the "circle" (it looked like a C insted of an O). There was only enough of it left to barely hang on to the clutch. It was obvious that this had been ran this way for a while because there was wear from the chain on the splines. I'm amazed that thing didn't explode too.

 

[SawTroll]

Way to go. You use the old run a sprocket well beyond its useful life to get a Stihl vs Husky supplier argument going.

It is not an argument, just a friendly discussion.