Stupid amount of chain stretch?

[Westboastfaller]

Take a video and link here

We would have a hard time with the saw in our hands.
A video of what?

 

[magnus333]

Welp, just got back from the dealer after 2 trips. They didn't have anything in stock, so they ordered up a new drum and also a spur sprocket. The silver techs exact words were "I'm just as clueless as you" after messing with it for nearly an hour. They were able to observe the full rotation chain sag, even with a brand new chain and sprocket off their shelf.

I'm going to cut what I can until Monday when I bring it in again for service, this time the gold tech will be there. I'll update whenever there's progress.

Thanks again everyone for the great support, and have a great weekend!

 

[Westboastfaller]

I've only used stihl 7tooth until now. Though I had planned to try a china 8 tooth today.
I measured the distance from the inside to outside on the stihl rim sprockets just now and it was exactly 6mm on every tooth. They don't appear to be out of center visually or by measure.


Yes, using a new 8 tooth rim sprocket every rev the chain drops 1/8 off the bar for a single tooth worth of revolution and then comes back to snug immediately for the next 7. I don't have any new 7 tooth rim sprockets to test with, only worn ones, but it was similar with a warn one.



I loosely pushed the rim sprocket out towards the washer before running the test. If I really force it I can get the intermittent sag down to possibly 1/16th instead of 1/8th, but that's not 0.

My thought this morning was that it was the wrong washer since I saw some thinner looking ones on youtube and ebay but it appears to be correct when looking up the OEM part images. My washer is on the right. It's flat against a straight edge. The rim sprocket on the left has around 3-6 tanks of gas on it. I have no idea if that's typical wear for such little use, but I doubt it.
View attachment 873322
I did buy the saw new, no one else has ever used it. In fact, I've barely used it and I think I've had this issue since day one.

I'm going to head to the dealership today and grab a new bearing, drum, washer and see if they have a spur socket I could try. The only remaining thing that seems likely is the chain pulling the drum and leaning the sprocket. The STIHL rim sprockets do seem to have a lot of play (easily able to create an oval trajectory) but that should self-correct I would think. I carefully measured the drum spine but it was perfect.

I've bent a crank before and broken another on some mowers back when I had a lawn business years ago. That takes an extraordinary amount of force and the saw hasn't been exposed to anything even remotely like that so I don't know how that would have happened. I rotated the drum a lot by hand watching the gap between the plastic and drum and it never changed. I would think that gap would get bigger and smaller if it was a bent crank.

Thanks again for all the help!

K..just read the latest update
Looking forward.
Cut safe, our Brother.

____________


For the most part, I agree with much of what you have said above.
Unbelievable! 3 to 6 tanks on the one sprocket in the forefront? WOW! It LOOKS like somewhere up between 160 to 220 tank range. About where I would change it out after my second chain.

Good call going to the saw shop.
Hey, you have them intrigued, Man! You have the hook in 'em now. Get them to rob the part(s) to get you going? It' sounds very important. Get your azz back down there!

Enjoy your weekend.

 

[toadman]

Something is very wrong if that sprocket pictured has only 10 tanks through it.
My 661 has seen over 120 gallons, so lots more than 400 tanks (I think, not entirely sure on tank volume, I rarely run fully dry) and been my primary bucking saw running 12+ hr days cutting trash logs into firewood, only stopping for fuel ups & on occasion to go deliver wood in that span.
It still looks much better than that...
edit; I got that wrong.
My 3rd sprocket in that span, I have been swapping between a 7 & 8. I wore out the original 7 to the point the chain was binding. The second 7 looks about like that, with 100+ tanks, and my 8 is about to be replaced.

 

[HarleyT]

Take a pic of your rim sprocket sitting on the drum spline. In many cases Stihl has a different size spline than aftermarket rims, and the rim will have a large amount of slop on the spline, that might be what you are dealing with.

 

[Ol' Brian]

Years back I had my saw shop make me 4 loops of Oregon chain (don't remember what number) for my Husky 55. That chain did the exact same thing as what the OP is describing here, except without the "every revolution" thing. Stretched like crazy, couldn't get a full tank out of it without having to tighten halfway through the tank. Eventually ran out of travel on the adjuster, just like the OP.

I finally threw those loops away, replaced the rim sprocket and have had no problems like that since. I figure Oregon let a bad batch of chain get out the door.

Also, removing links from the stretched chain will not really help you, sure it will shorten the chain, but when it is that stretched, your pitch is so far off by that point that the chain is going to chew up your rim sprocket and nose sprockets. Best to just throw those chains away.

 

[farmguywithasaw]

I’m curios exactly how much is the saw oiling. I the tank empty when the gas is. Is the oil getting to the bar in the proper place

 

[Bwildered]

There's usually 3 reasons a chain will stretch like yours.
1. The chain is blunt
2. You think the chain is sharp
3. The chain is really really blunt

Heat is the main reason chains stretch, being blunt creates the heat.

 

[Ol' Brian]

There's usually 3 reasons a chain will stretch like yours.
1. The chain is blunt
2. You think the chain is sharp
3. The chain is really really blunt

Heat is the main reason chains stretch, being blunt creates the heat.

I'm not sure I'm following you... What do you mean by being "blunt"?

If the chain is sharp, and it's cutting good, and making good chips, how can it be "blunt"? To my way of thinking, if a chain is "blunt", it won't cut. Like after you hit a big spike nail square on while bucking a log blunt.

 

[farmguywithasaw]

Is this blunt lol nah I think means to say the chain is dull when you are bucking are you pushing really hard with the dogs because that can cause chain stretch as well. Oh and it’s perfectly legal in Canada

 

[SteveSr]

"Blunt" is south of the equator translation for "dull"...

 

[Okie]

Chain stretch that much that fast must be from grit.
You said it's not getting hot and you can see the stretch when you compare it too a new chain. What you say indicates that it's actually the link rivets wearing, not link and metal stretch due to heat. You need to keep in mind that when a chain stretches the drive links will runi/damage a sprocket fast.
You say it might be the shaggy bark dusty wood. (and it happens fast)
Why not do a cut test on another type wood?????
(or no wood at all, just keep piss revving the saw in the air for awhile then look at the chain then test on another type wood even a soft wood at first.)

You say: Please help me be less PUNY! I don't want my mom to like my brother better than me! I MUST CUT MORE WOOD THAN HIM!!! You are my only hope.

Maybe have your Bro and Mom operate your saw and see what happens.
(so as to rule out the possibility that it's the way you are holding your mouth and to make sure he is not better than you but do not let mom watch when Bro is testing YOUR saw so as mom would not think you are more PUNY.
Another thought: See if you can get Bro to test by cutting you a couple ricks of wood with your saw while you watch.

 

[Bwildered]

If the wood is really dirty, then it will blunten the chain first, heat will be generated so the oil will be insufficient to lubricate the rivets & they will wear, the OP just has to put up some pics of the chain after one of the chain stretching cutting sessions.

 

[kevin j]

You said the chain gets tight and loose with every revolution of the sprocket and clutch drum, is that correct? That would rule out a bad crank but it could be an out of round clutch or sprocket, which I think you are already checking. If the engine was turning over and getting looser and tighter the end of the crank could be bent from new. Try rotating the fly wheel and engine crank to different locations then moving the chain by turning the clutch at each of those locations. Would that make any difference in this loose tight scenario

 

[Bwildered]

"Blunt" is south of the equator translation for "dull"...

Just consider your vocabulary expanded one notch beyond planet America

blunt
/blʌnt/

adjective

1. 1.
   (of a cutting implement) not having a sharp edge or point.
   "a blunt knife"

sharp
Opposite
adjective

1 blunt

 

[HarleyT]

Take off the sprocket cover, and take a pic of the chain on the sprocket and chain/bar still in place.

 

[HarleyT]

Just consider your vocabulary expanded one notch beyond planet America

blunt
/blʌnt/

adjective

1. 1.
   (of a cutting implement) not having a sharp edge or point.
   "a blunt knife"

sharp
Opposite
adjective

1 blunt

I judge a man by the direction that his toilet swirls....

 

[deye223]

I judge a man by the direction that his toilet swirls....

Dunny does not swell in my country.

 

[BangBang77]

I had a similar issue this week that still has me puzzled.

I run a 20" Sugihara on my 461 most of the time. Typically RS chain unless I'm in something nasty. I was at my dad's farm last week cutting wood (red oak). Dropped 3 trees on the ground and bucked the main trunk with my 066 and grabbed my 461 to finish out the bucking. I couldn't get the chain to tension up? I ran the adjuster to the full end of travel and still had excessive slack/sag with a fairly new RM chain. I had plenty of remaining slot left so I know it wasn't butting up against the bar stud like you see with an excessively worn chain. Sprocket looked good but I threw a new one on there and grabbed a BNIB RS chain and attempted to re-tension. No dice - still at the end of adjuster travel with chain slack. Tried a few different chains with the same result.

I then grabbed a 460 to see if I could duplicate the failure mode. Same problem. I then threw a 24" Sugihara on both the 461 and 460 and it tensioned up perfectly. Finished out the day with the 24".

When I got home, I checked everything again. Clutch, drum, drum bearing, sprocket, bar alignment, bar sprocket, various chains, etc. Same dang problem. I tried the 20" bar on every saw I have that runs a 3003 mount - 026s, 360s, 261, 460, 461, 066. Same problem on every saw.

Finally overlaid the Sugihara bar over a BNIB Stihl 20" ES bar and found the tensioner holes on the Sugi to be about .250" - .375" closer to the tip of the bar. This isn't uncommon when comparing different manufacturers though. I did the same with a BNIB Cannon 20" Superbar and the adjuster holes were very close between the Stihl ES bar and the Cannon.

At the end of the day, I overlaid the Stihl ES on the Sugi and clamp it down on my bench. Transfered the Stihl holes to the Sugi bar with a transfer punch and drilled new adjuster holes with a .250" carbide bit on my drill press.

Everything works as it should now but I'm not sure why I needed to drill new adjuster holes at all. I've been running this 20" Sugi bar for over a year now with no issues.

It Stihl has me scratching my head...

 

[Westboastfaller]

I had a similar issue this week that still has me puzzled.

I run a 20" Sugihara on my 461 most of the time. Typically RS chain unless I'm in something nasty. I was at my dad's farm last week cutting wood (red oak). Dropped 3 trees on the ground and bucked the main trunk with my 066 and grabbed my 461 to finish out the bucking. I couldn't get the chain to tension up? I ran the adjuster to the full end of travel and still had excessive slack/sag with a fairly new RM chain. I had plenty of remaining slot left so I know it wasn't butting up against the bar stud like you see with an excessively worn chain. Sprocket looked good but I threw a new one on there and grabbed a BNIB RS chain and attempted to re-tension. No dice - still at the end of adjuster travel with chain slack. Tried a few different chains with the same result.

I then grabbed a 460 to see if I could duplicate the failure mode. Same problem. I then threw a 24" Sugihara on both the 461 and 460 and it tensioned up perfectly. Finished out the day with the 24".

When I got home, I checked everything again. Clutch, drum, drum bearing, sprocket, bar alignment, bar sprocket, various chains, etc. Same dang problem. I tried the 20" bar on every saw I have that runs a 3003 mount - 026s, 360s, 261, 460, 461, 066. Same problem on every saw.

Finally overlaid the Sugihara bar over a BNIB Stihl 20" ES bar and found the tensioner holes on the Sugi to be about .250" - .375" closer to the tip of the bar. This isn't uncommon when comparing different manufacturers though. I did the same with a BNIB Cannon 20" Superbar and the adjuster holes were very close between the Stihl ES bar and the Cannon.

At the end of the day, I overlaid the Stihl ES on the Sugi and clamp it down on my bench. Transfered the Stihl holes to the Sugi bar with a transfer punch and drilled new adjuster holes with a .250" carbide bit on my drill press.

Everything works as it should now but I'm not sure why I needed to drill new adjuster holes at all. I've been running this 20" Sugi bar for over a year now with no issues.

It Stihl has me scratching my head...

I have to assume the 24" sugi. Has
the adjuster hole 'the same' as the Stihl 3003 and not the same as the 20" sugi"?
Maybe it's something they have changed to be more suited to the Stihl instead of an 'inbetweener' design?

If you can confirm that then I can offer you some possibilities regards to as why it worked for a year without issue?