lumberjack
Young man on the go
Huh, never thought about that! Who'd want 50+ never sharpened, once dulled Stihl chains anyways?
When to replace sprocket?
- Thread starter emr
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brendonv
Tree Hugger
Me Me Me.
Spur sprockets when they have an appreciable groove worn in them...like 1mm...putting new chains on a worn sprocket just wears the chain quicker, trying to force a new chain to run in the old one's groove...
Rim sprockets 'float' a bit on the spline,allowing a new chain to find its 'fit' so last longer, again, once there is a definite groove, the drive links will drop lower and bottom out on the spline...
Rim sprockets 'float' a bit on the spline,allowing a new chain to find its 'fit' so last longer, again, once there is a definite groove, the drive links will drop lower and bottom out on the spline...
woodworkingboy
TreeHouser
Whenever I hear that Bailey's business is down, I order new sprockets.
Al Smith
Mac Daddy
That two chains per sprocket deal goes back maybe 30 or more years .I don't think many adhere to it though .
Cobleskill
Treehouser
We musta learned that on the farm.
Cut4fun
Redneck Chainsaw Repair
- Joined
- Nov 27, 2007
- Messages
- 2,635
I just replace when worn by looking, not by chains used.
Straight from Madsen's link
When A Sprocket Should Be Replaced
Worn sprocket good general rule is: one sprocket will last for the complete life of two chains. If you are running an Oregon sprocket, another way of determining wear is to look at the wear bars. Oregon sprockets have small recesses cast into their surfaces. When the chain wears down to them, it is time to replace the sprocket. If the sprocket you have doesn't have wear bars, we recommend replacing it when it has 1/64" of wear on its surface.
From what we see in our shop, most sprockets are not replaced often enough. Too many pro saw operators apply the "If it ain't broke, don't fix it" rule instead. This is like running the tires on your truck until they won't hold air.
Sprockets need to be replaced because they get out of pitch. Sure they will eventually break if they are run long enough, but this usually doesn't occur until they are extremely worn. When a sprocket wears to a smaller diameter, it gets "out of pitch."Out of pitch conditions cause the chain to bind as it goes around the sprocket. This causes the chain to wear prematurely and affects its cutting performance. This usually occurs long before the sprocket is so worn that it breaks.
Straight from Madsen's link
When A Sprocket Should Be Replaced
Worn sprocket good general rule is: one sprocket will last for the complete life of two chains. If you are running an Oregon sprocket, another way of determining wear is to look at the wear bars. Oregon sprockets have small recesses cast into their surfaces. When the chain wears down to them, it is time to replace the sprocket. If the sprocket you have doesn't have wear bars, we recommend replacing it when it has 1/64" of wear on its surface.
From what we see in our shop, most sprockets are not replaced often enough. Too many pro saw operators apply the "If it ain't broke, don't fix it" rule instead. This is like running the tires on your truck until they won't hold air.
Sprockets need to be replaced because they get out of pitch. Sure they will eventually break if they are run long enough, but this usually doesn't occur until they are extremely worn. When a sprocket wears to a smaller diameter, it gets "out of pitch."Out of pitch conditions cause the chain to bind as it goes around the sprocket. This causes the chain to wear prematurely and affects its cutting performance. This usually occurs long before the sprocket is so worn that it breaks.
Altissimus
TreeHouser
... I replace when broken ... no sooner...
MasterBlaster
Administrator Emeritus
Nah, you should shoot for a 'lil sooner than that.
Al Smith
Mac Daddy
They are only about 4 bucks a pop ,Stihl maybe 7 .You can screw more stuff up than that.
HolmenTree
Banned
Yes the drive sprocket wear limit is a concern, but how many saw operaters look at the bar's nose sprocket?
Both sprockets work together in unison.
Willard.
Both sprockets work together in unison.
Willard.
woodworkingboy
TreeHouser
I look at the nose sprocket when cleaning the saw. If it doesn't spin around when being blown with the compressor, something isn't kosher.
That's why I like the old dental picks I have, I have one that will get right in round the nose sprocket, gets out a surprising amount of gunk.
Al Smith
Mac Daddy
A drywall saw works well as a bar cleaner .
Cut4fun
Redneck Chainsaw Repair
- Joined
- Nov 27, 2007
- Messages
- 2,635
I should have taken a pic of the little rear handle mac with a spur sprocket I took in last year. Problem was the chain kept coming off he says. Well lookie there the chain has wore right through the spur and cut it off the clutch drum. Made a nice throwing star 
.
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Al Smith
Mac Daddy
Tom had one like that .It was one of the ground saws his grunts used . I think it was an 039 which really wasn't much of a saw to begin with . One of those 50 dollar specials he ran across .
Butch im sure someone told me years ago that a good adage was 4-2-1. 4 chains, 2 sprockets, 1 guidebar.
.General training circles here give the cliched 2-3 chains per sprocket or Stihl quote .5 mm wear but along with Brians analogy of tyres the variables of chain tension, sharpness or lubrication even can make massive differences.
