finn
Well-known member
Bent from a bad pinch in one case. Severely worn grooves mostly. I don’t ever recall changing a drive sprocket, although I know at least one saw, the MS460, needs one.The rule of thumb by the manufactures in the industry is 4:2:1.
4 chains to bar replacement
2 chains to a sprocket replacement
The two chains should be alternated until worn out with the same sprocket. Sprocket replaced and two new chains ran.
If you run a sprocket longer then you unduly wear out the new chains due to the pitch being off from wear.
A rim sprocket makes it cheaper as you don’t have to replace the whole clutch drum every time.
Quote from oregon
"How long should the drive sprocket on my saw last?
You should replace drive sprocket systems after every two chains, or sooner. It's important not to run a new chain on a badly worn drive sprocket."
Oregon chainsaw sprockets
And from Stihl
Page 17
Something must of been really wonky to require bar replacement before sprocket replacement.
Not all wood is pristine , especially when you’re cutting tops in logged over areas. Lots of dirt in the wood after the harvester, feller butcher and skidder are done getting the marketable timber out of the woods.
Part of the cost of getting so called free firewood.





