Stupid amount of chain stretch?

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magnus333

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Using a MS 661 and my chains (STIHL/Oregon) won't stop stretching until I run out of room on the bar. It's EXTREMELY excessive, as in I tighten the chain and make 5-7 cuts on a puny 8 inch tree and the chain is already sagging so low it's flopping off the bar at a 45 degree angle and I can fit a finger or two between the chain and bar. Stuff I've done:

1) Verified the chain is not getting hot. First, it doesn't have time to, I use it for 30 seconds and it's already sagging off the track but I also carefully measured with an infrared thermometer numerous times, keeping the chain between 85-95F (30-35C) while the bar pushed 115-120F (46-48C).
2) I pushed the pin in and jacked up the oil to max. It's running 1:1 with fuel and never goes dry.
3) Replaced the sprocket & chain. Sprocket looked pretty worn after maybe 10 tanks of gas. Brand new sprocket with a new chain did the same exact thing and is already starting to look worn after maybe 3-4 tanks of gas.
4) Replaced the sprocket & chain & bar. Switched from a stihl 28 to oregon 20. Same thing.
5) Sharpened every chain like a boss to the point of idiocy, as many as 6 times per tank of gas. It's not dull.
6) Tried loose, moderate and too-tight levels of tightening. As in 1/8" sag, just barely snug to the bar and snug + another quarter turn. Zero difference between the three levels of tightening. I got so desperate I even tried never tightening which delivered the... "expected" results of a chain flying through the air like it just didn't care.

The saw cuts like a dream, smooth as butter with no force necessary and it murders trees like those Murder Hornets murder bees, but I literally spend more time tightening than I do cutting. Meanwhile my cheap CHINESE-CHOPPA!, a no-name brand 45cc, doesn't have these issues and cuts just fine, giving me some assurance I'm not a complete idiot, but it's... TOO PUNY of a saw!

I read that really dirty wood can cause chain stretch, but I assumed that was from heat buildup and dullness? I'm cutting shaggy bark juniper in a super dry and excessively dusty environment so maybe that's it, but I don't understand the physics of this nor why it wouldn't apply to the China-Choppa. Nor what to do about it. I'm about to start removing links but that doesn't seem like it'll solve the problem, just delay an inevitable break.

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...
 
I had a little Forester B&C that I got cheep for MS180 that seemed like a rubber band.
Not sure if it was one or both but finally it found equilibrium.
I can say that I'd never seen anything stretch like it before, except for new nylon strings on my little guitar....
 
Do you hold up on the nose of the bar when you tighten the chain?
Yeah I always hold up the bar.

For oil I use the generic home depot stuff in bulk. I thought about straining some used motor oil I have kicking around as an experiment but again, if the chain isn't getting hot and isn't getting dull I don't see any reason it would make a difference. I sure as hell ain't no scientist, but I'll experiment with just about anything at this point.

The chains are a full comp stihl 28, full skip stihl 28 (a few of them), and oregon 20. The chains that don't stretch are china specials. Maybe I should buy a cheaper chain...?
 
When you say excessively dusty conditions, do you mean dust from dirt / sand? I would imagine that plus bar oil makes a pretty effective grinding compound. That could be the source of your excessive wear, which is what chain stretch is, wear in the links / pins.
 
The adjuster isn't backing off, the chain is stretching. A new one hangs about 1 inch lower on a nail compared to a stretched one.


Yeah the dust is from dirt, it's high desert here, nearly zero humidity. Every foot step kicks up a waft of dust. The trees are coated in it in addition to all the critter debris that get caught in the shaggy bark, also many trees have significant rot in the stumps (which I need to remove per my commercial permit specs). I didn't mention it before but cutting a decent stump (30-36"), even in a single short cut basically stretches the chain from perfectly tightened to falling off the bar in about 30 seconds and it doesn't come back from cooling (still only 95F after the cut). I try to sweep stumps off on the outside as much as possible, only to find a den of dirt and decomposed rot in the middle 65% of the time.

So that seems like it could be it. But what do i do about it. Maybe strained motor oil is the way to go and up my oil to gas ratio considerably coating the forest service in a thin layer of EPA approved sludge!??!
 
When you say excessively dusty conditions, do you mean dust from dirt / sand? I would imagine that plus bar oil makes a pretty effective grinding compound. That could be the source of your excessive wear, which is what chain stretch is, wear in the links / pins.

The adjuster isn't backing off, the chain is stretching. A new one hangs about 1 inch lower on a nail compared to a stretched one.


Yeah the dust is from dirt, it's high desert here, nearly zero humidity. Every foot step kicks up a waft of dust. The trees are coated in it in addition to all the critter debris that get caught in the shaggy bark, also many trees have significant rot in the stumps (which I need to remove per my commercial permit specs). I didn't mention it before but cutting a decent stump (30-36"), even in a single short cut basically stretches the chain from perfectly tightened to falling off the bar in about 30 seconds and it doesn't come back from cooling (still only 95F after the cut). I try to sweep stumps off on the outside as much as possible, only to find a den of dirt and decomposed rot in the middle 65% of the time.

So that seems like it could be it. But what do i do about it. Maybe strained motor oil is the way to go and up my oil to gas ratio considerably coating the forest service in a thin layer of EPA approved sludge!??!
Are shure you are using the corrcet pitch chian because there is 3/8 low pro and regular 3/8 pitch those can not interchange . Just something to check
 
How about taking the chain off and laying it out on a flat surface, push it together so it is as short as possible, then stretch it out. Measure the distance. Then use it like you say until a finger space hanging down, maybe twice, then measure again. This should give you an idea if the chain is really stretching or something else is going on. I would think there would be a big difference in the used chains and the new one. Oil slings off the end of the bar like the pictures in manuals?
 
Using a MS 661 and my chains (STIHL/Oregon) won't stop stretching until I run out of room on the bar. It's EXTREMELY excessive, as in I tighten the chain and make 5-7 cuts on a puny 8 inch tree and the chain is already sagging so low it's flopping off the bar at a 45 degree angle and I can fit a finger or two between the chain and bar. Stuff I've done:

1) Verified the chain is not getting hot. First, it doesn't have time to, I use it for 30 seconds and it's already sagging off the track but I also carefully measured with an infrared thermometer numerous times, keeping the chain between 85-95F (30-35C) while the bar pushed 115-120F (46-48C).
2) I pushed the pin in and jacked up the oil to max. It's running 1:1 with fuel and never goes dry.
3) Replaced the sprocket & chain. Sprocket looked pretty worn after maybe 10 tanks of gas. Brand new sprocket with a new chain did the same exact thing and is already starting to look worn after maybe 3-4 tanks of gas.
4) Replaced the sprocket & chain & bar. Switched from a stihl 28 to oregon 20. Same thing.
5) Sharpened every chain like a boss to the point of idiocy, as many as 6 times per tank of gas. It's not dull.
6) Tried loose, moderate and too-tight levels of tightening. As in 1/8" sag, just barely snug to the bar and snug + another quarter turn. Zero difference between the three levels of tightening. I got so desperate I even tried never tightening which delivered the... "expected" results of a chain flying through the air like it just didn't care.

The saw cuts like a dream, smooth as butter with no force necessary and it murders trees like those Murder Hornets murder bees, but I literally spend more time tightening than I do cutting. Meanwhile my cheap CHINESE-CHOPPA!, a no-name brand 45cc, doesn't have these issues and cuts just fine, giving me some assurance I'm not a complete idiot, but it's... TOO PUNY of a saw!

I read that really dirty wood can cause chain stretch, but I assumed that was from heat buildup and dullness? I'm cutting shaggy bark juniper in a super dry and excessively dusty environment so maybe that's it, but I don't understand the physics of this nor why it wouldn't apply to the China-Choppa. Nor what to do about it. I'm about to start removing links but that doesn't seem like it'll solve the problem, just delay an inevitable break.

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...
Sprocket looks worn after 10 tanks? You sure you have yopur cains and bars matched to the right pitch?
 
Buy a new sprocket, chain and bar all the same pitch . put them on together, buy some good chain oil and cut wood.
a bad bar or gear will ruin a new chain about as fast as you start the saw. make sure the sprocket bearing is good and look at the crankshaft where the bearing rides
 
Wow lots of replies, thanks!

1) Everything is the regular 3/8, 0.050
2) I can try to take a video this weekend, I'll be out cutting every day. I was hoping to actually cut straight though the weekend since it's the last 3 days of my permit. There's 0 cell signal out there so may not get it uploaded till Monday.
3) I already measured the used chains and new ones and there is a huge difference as I mentioned before, used ones drop about 1 inch lower than new ones and that's after just a few tanks of gas. It's very clear that a new chain is way shorter.
4) Oil does spray off the bar per the manual. Lately I check it every other cut this has gotten so frustrating and there's a myriad of block letters drawn on various objects in my area. ;)
5) Crankshaft endplay! This one I have no idea about, I don't know what's normal or how to check it. Any tutorials or advise?
6) Already did the new sprocket chain and bar, all 3/8.
7) Sprocket bearing was new at the start of the season and I haven't checked it. Will do.
8) The oil doesn't have any specs on thickness, though it's pretty thick this time of year at 40-50F ambient. I was thinking super thin oil to wash it out, but you're saying thicker is better when cutting dirty? Either way, it's something new to try.

Appreciate all the help. I'll go look at it now.
 
Wow lots of replies, thanks!

1) Everything is the regular 3/8, 0.050
2) I can try to take a video this weekend, I'll be out cutting every day. I was hoping to actually cut straight though the weekend since it's the last 3 days of my permit. There's 0 cell signal out there so may not get it uploaded till Monday.
3) I already measured the used chains and new ones and there is a huge difference as I mentioned before, used ones drop about 1 inch lower than new ones and that's after just a few tanks of gas. It's very clear that a new chain is way shorter.
4) Oil does spray off the bar per the manual. Lately I check it every other cut this has gotten so frustrating and there's a myriad of block letters drawn on various objects in my area. ;)
5) Crankshaft endplay! This one I have no idea about, I don't know what's normal or how to check it. Any tutorials or advise?
6) Already did the new sprocket chain and bar, all 3/8.
7) Sprocket bearing was new at the start of the season and I haven't checked it. Will do.
8) The oil doesn't have any specs on thickness, though it's pretty thick this time of year at 40-50F ambient. I was thinking super thin oil to wash it out, but you're saying thicker is better when cutting dirty? Either way, it's something new to try.

Appreciate all the help. I'll go look at it now.
Idk I have never had a chain stretch that bad. If the dirt is clinging to the chain with a thick oil I would try atf. Where I live it can range from 30 degrees C down to -30C I have found if you use a light or some “all season” oil when it’s hot out the chain will stretch some. So I guy could experiment with a heavier and a lighter oil. I have cut dirty wood but I sounds like the dust you are dealing with is quite fine. Guy should make sure the air filter is clean and up to par every day. I know the fire crews have trouble with the stock filter not being enuf. You can get a oil-able foam pre filter for some saws.
 
I took my 311 out last weekend with a stihl 25" bar and chain that was on it when i got it. I had to tension it twice which is very odd...i normally don't have to touch a chain for a tank of gas. I put on my new Archer chain and it went a full tank and no stretch.

Personally i dislike stihl chains. When i worked at a saw shop years ago most of the chains that i had to take a link out of were Stihls.

Sent from my LM-G820 using Tapatalk
 
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