Yes another chain/saw question

[Ryan'smilling]

Does an 8 pin .325 pitch rim even exist for a large Stihl spline?
I run 9 pin .325 pitch rims and 82 DL chain on 2 of my 361's.

I'm not sure why this bothers you @sb47 ; is this something you have been tracking for a while? Or just something you happen to notice the last time you put a chain on your saw?

1 grind on this chain
View attachment 949859

4 grinds on this chain.
View attachment 949861

Plenty of adjustment left.
View attachment 949862

9 pin is the smallest .325 sprocket for large spline. The 261 is mini spline though, so it can use an 8 pin. I'm not sure what spline size the 362 uses, but I think the OP says that it's 3/8 on that saw. Not really sure though, this has been a confusing ride.

 

[HarleyT]

I believe he stated the chain had been run on a rim drive sprocket that was not worn out and the spur in the picture was sort of an experiment to see if things changed.

Not as I read things, but hey, I am usually wrong.
Here is his pic of the original sprocket.

 

[sb47]

I believe the original question was, I used to file my chains all the way back to the witness mark, now I run out of adjustment first, care to discuss this. It wandered to worn sprockets make chains stretch. The pictures (early on) were to show how much adjustment there would be for a new chain assuming the travel of the adjuster and the length of the slot ran out together.

That does not explain why half the adjustment is used up with all new parts and no wear has been applied. It also does not explain that in the past I have much more adjustment available at the start of a new chain.

 

[sb47]

I believe he stated the chain had been run on a rim drive sprocket that was not worn out and the spur in the picture was sort of an experiment to see if things changed.

Correct. I switched to a spur drive to see if it changed the adjustment length. It did not.

 

[HarleyT]

And then he put on the new sprocket.
I just requested a pic of the original one.

 

[HarleyT]

I was not venturing any guesses as to what the problem may be, just requesting a better pic. I like to have as much info as possible.

 

[LoneOak]

Running a while on a shot sprocket will "stretch" a chain badly, it constantly needs tightening, damages the bottom drivers, and the chain needs a link taken out after a short time.
What model saw is that rim sprocket on?

That rim is on a MS 361 that runs my 28" bar.

Again, I have never had to remove a driver from a chain due to a shot rim or spur. Nor have any of my chains been damaged by a shot rim or spur.

The middle one wears the 28" bar.

 

[dave ensign]

It seams some read but others think your saw was made in STAR TREK. IT WAS NOT.

 

[SteveSr]

That does not explain why half the adjustment is used up with all new parts and no wear has been applied.

This is called "design margin". It leaves room to accommodate other sprockets with more teeth.

It also does not explain that in the past I have much more adjustment available at the start of a new chain.

The bottom line is that chains and sprockets are designed to "share" the load by contacting several sprocket teeth at the same time. When the load is shared the wear on each component is minimized.

If you put a mis-matched set of new and old/worn the components will wear until this balance point is reached leading to accellerated wear on the "new" component, be it chain or sprocket.

 

[J D]

Is it possible you previously had a larger rim on the saw(s) & at some point that changed?
I think trying a larger rim would be a good idea anyways, you may find it cuts as well for you & solves the problem

 

[djg james]

I've been watching this thread and I'm not sure if the problem has been solve. I was wondering, if a person could just drill a new hole (3/16?, 1/4"?) at the right position on the bar to accommodate a half used chain? Use the original tensioner hole until it's maxed out. Then switch to the new one.

 

[sb47]

A few more pictures.
In this picture you can see the adjuster slot is just past the cover plate and when the saw was new that slot did not show with a new chain. But now it does show with a new chain.

Here are 4 bars stacked on top of each other and as you can see they are all identical. These are the old bars that I have replaced and keep for spares. So the bar is exactly the same as before.

This is how it use to be when the saw was new. See how the bar sits with all the adjustment forward. This allows for maximum adjustment as the chain stretches. This is how it should be with a new chain.

Notice how the adjustment slot is not showing with the cover on. This is how it is supposed to be.

 

[Philbert]

I am at a loss to explain your original problem. But I did want to comment on the way that the term “chain stretch“ is being used in a couple different ways in this thread, and how to maybe address your issue.

As stated above, “chain stretch“ is when the rivets or rivet holes wear, which increases the spacing between the drive links, essentially changing the pitch of the chain slightly.

When the drive links wear, sometimes due to drive sprocket wear, ‘pitch’ , as measured between the tips of the drive links, may also not align with the pitch of the original sprocket.

If you remove a drive link from a chain loop to accommodate the “stretch“ in either case, you still have a chain that is slightly “out of pitch“.

So, it might be better to remove a link from a new loop, if that will fit, so that the drive links and drive sprocket are both original pitch, unless you can get a larger sprocket, which would do the same thing. Hopefully, this will give you back your full range of tension adjustment.

Better than removing a drive link later on, when the chain lube is worn.

Philbert

 

[sb47]

I am at a loss to explain your original problem. But I did want to comment on the way that the term “chain stretch“ is being used in a couple different ways in this thread, and how to maybe address your issue.

As stated above, “chain stretch“ is when the rivets or rivet holes wear, which increases the spacing between the drive links, essentially changing the pitch of the chain slightly.

When the drive links wear, sometimes due to drive sprocket wear, ‘pitch’ , as measured between rivets, may also not align with the pitch of the original sprocket.

If you remove a drive link from a chain loop to accommodate the “stretch“ in either case, you still have a chain that is slightly “out of pitch“.

So, it might be better to remove a link from a new loop, if that will fit, so that the drive links and drive sprocket are both original pitch, unless you can get a larger sprocket, which would do the same thing. Hopefully, this will give you back your full range of tension adjustment.

Better than removing a drive link later on, when the chain lube is worn.

Philbert

Very good points. I'm gonna try to get a bigger sprocket and see what happens. I'm gonna call tomorrow and see if it available.

 

[sb47]

How about a survey. Are there any other stihl owners with the same issue? Does the adjustment slot look normal the same way?

 

[LoneOak]

For me this is a non-issue as there are only two outcomes.
Does the chain tensioner apply necessary tension to the chain?
1. If yes, continue to torque bar nuts.
2. If no, investigate and correct the problem.

Do all of your bars have blackened tips? That is an issue to me, perhaps your roller tips are wearing out prematurely?

 

[sb47]

For me this is a non-issue as there are only two outcomes.
Does the chain tensioner apply necessary tension to the chain?
1. If yes, continue to torque bar nuts.
2. If no, investigate and correct the problem.

Do all of your bars have blackened tips? That is an issue to me, perhaps your roller tips are wearing out prematurely?

No that is the bar off the very first ms290 I bought 20 years ago. I guess you could say I hold on to useless things. lol
It is the only bar that the bearings went out on in 20 years of cutting firewood. That bar has hundreds of hours on it. It's been hanging on a nail in my shop for years. I guess I should throw it out. I have a bunch of worn out chains still hanging on the wall as well that need throwing out.

 

[LoneOak]

No that is the bar off the very first ms290 I bought 20 years ago. I guess you could say I hold on to useless things. lol
It is the only bar that the bearings went out on in 20 years of cutting firewood. That bar has hundreds of hours on it. It's been hanging on a nail in my shop for years. I guess I should throw it out. I have a bunch of worn out chains still hanging on the wall as well that need throwing out.

Put them on Ebay! plenty of peeps looking for that kind of stuff to make knives and axes!!

 

[farmer steve]

No that is the bar off the very first ms290 I bought 20 years ago. I guess you could say I hold on to useless things. lol
It is the only bar that the bearings went out on in 20 years of cutting firewood. That bar has hundreds of hours on it. It's been hanging on a nail in my shop for years. I guess I should throw it out. I have a bunch of worn out chains still hanging on the wall as well that need throwing out.

 

[SteveSr]

How about a survey. Are there any other stihl owners with the same issue? Does the adjustment slot look normal the same way?

How about put up some better photos of your stretched chains from both side and top showing the cutters? BTW, what are you using for sharpening? Hand file, jig, grinder?