I always loosen b&c after operation.....Right?

[Lakeside53]

Call it 11 ppm... say 100 degrees rise C (way more than reality.....)

11x10E-6 x 100 x 50 inches... = 0.055 inches growth in a 50 inch chain inches..


A 150 inch chain.... 0.165 inches.. now that's a lot of molecular forces that have to go somewhere..

Check my math though...

 

[Lakeside53]

Yeah, I didn't know what the figure was. I thought the expansion rate was more than that. What do you think; are bent cranks and ruined seals an old wives' tale?

nope... if the chain is real real tight, as it cools it has to move something or "stretch". It does both... and the bearings take it in the shorts.

Just run them a bit loose - like you're supposed to anyhow...

 

[NPKenny]

That's super strange and I'd like to see some feedback from the Tech's on this... I've NEVER loosened a chain when done for the day or week or however long. I've never had a bearing go bad either. As far as the chain stretching, Stihl chain and the Oregon LGX I have NEVER had stretch a bit no matter the heat conditions... Some of the other Oregon and Carlton I noticed would loosen up a couple times before being consistent, but never the 2 aforementioned... If a chain really stretches, wouldn't that be dangerous? How exactly and what exactly stretches on a chain. I doubt the links can, I don't think the pins that hold the links together can.?.? Which means by my guessing maybe the drive links and how they sit on the clutch??? Explain exactly what stretches eh?

opcorn:

In relation to the Stihl Chain stretching...I had never noticed any chain stretch with a 20" bar on my 361. I put the same bar and chain set-up on my 660 with an 8-pin sprocket for about 4 tanks. That chain in now noticibly more relaxed and maxes out the adjuster on my 361, to the point that I may need to run and 8-pin sprocket on the 361 or pull a link from the chain.

I have seen a chain cinch up as well, so as a precaution, I always take the tension out of the chain before putting the saw to bed. It is just like my wife loosens her bow after she has smoked it on her fiddle.

 

[Lakeside53]

Chains don't permanently stretch... the bearing journals of the links wear... each tiny wear x the links = growth.

 

[GASoline71]

I have never, ever loosened a chain at rhe end of a day of cuttin'.

Usually too tired to give a crap...

Gary

 

[ciscoguy01]

sooo

nope... if the chain is real real tight, as it cools it has to move something or "stretch". It does both... and the bearings take it in the shorts.

Just run them a bit loose - like you're supposed to anyhow...

Have we decided it stretches alot or just a little??? And is the amount it does stretch enough to cause it to go through say 2 or 3 tightenings??

opcorn:

And is 5/100 of an inch enough to cause chain tightening??? I can see say 1/4", but 5/100??? I'm not sure about that... Great info though...

Don't Stihl chains come pre-stretched???

 

[Lakeside53]

It does not STRETCH.... It increases/decreases in length proportional to temperature.. and it's "a little", but if the chain is banjo-string tight, a little is a lot.

 

[spacemule]

I have never, ever loosened a chain at rhe end of a day of cuttin'.

Usually too tired to give a crap...

Gary

Ah, a Stihl user I see. . .

 

[gink595]

Think of it this way, say you have a sheet of steel that is cut to 20'X40'. That means when heated this sheet is now 20'5" X40'10". In all actuality, thats' no where near possible I don't believe.

Thats interesting you mentioned that well to me. I work for a steel building manufactuer (Nucor Building Systems) I just referenced my detailing manual and for our standing seam metal roof for every 200' of roof run from eave to peak we install a step in the roof or expansion joint. Here is what my manual says:
"CFR roof system is a raised seam metal roof which is designed to “float” to
accommodate thermal expansion and contraction. This is accomplished with
concealed sliding clips which allow for up to 3” of expansion and contraction"

I know this has nothing to do with chain saws but still has some value and thought some would find interesting. I've seen this work first hand while on some of this roofs it's unbelievble the movment of hot steel.

 

[kevlar]

If you adjust your chain when it is warm and you make it tight I believe there is a possability it could hurt your bearings,seals crank etc...With that being said who runs there chains that tight? and if you do loosen them after cutting!

 

[ciscoguy01]

Cool

Thats interesting you mentioned that well to me. I work for a steel building manufactuer (Nucor Building Systems) I just referenced my detailing manual and for our standing seam metal roof for every 200' of roof run from eave to peak we install a step in the roof or expansion joint. Here is what my manual says:
"CFR roof system is a raised seam metal roof which is designed to “float” to
accommodate thermal expansion and contraction. This is accomplished with
concealed sliding clips which allow for up to 3” of expansion and contraction"

I know this has nothing to do with chain saws but still has some value and thought some would find interesting. I've seen this work first hand while on some of this roofs it's unbelievble the movment of hot steel.

Neat info dude... But think about that, 3" in 200'. That's like .01% which is what I'd expect from something metal. I was thinking of it this way. I used to cut plate for heat exchangers. Sheets for them were 2"X8'X24'. Our tolerance was at +/- 1/32. Can you imagine what would happen if they were welded together and they would exchange heat at say 5 or 600 degrees, with expansion of even 2" on 24' that would be crazy. That would cause some serious issues, hence why I said I doubt it's possible if that could happen with that much expansion... That was mostly with Alloy plate, but they'd also use a carbon steel also such as 1045 sometimes also. They never used things like 1018 which is what standard carbon steel flats and rounds are like you'd use to weld your frame or general things...

opcorn:

 

[stevethekiwi]

never have loosened my chains. never will. never had an issue. end of story.

if your bearings fail because of the chain, you need a new bearing supplier or you bought a chinese saw.

 

[oneoldbanjo]

I don't automatically loosen my chain after every use - but I do make sure that there is just a bit of slack when I put them away in my heated basement. If the days cutting didn't provide some slack - then I will loosen the chain a bit.

I suppose the problem situation and the reason it is recommended to loosen the chain is that the Operators Manual has to account for every possible condition that your saw could experience - in all parts of the world that the saw is distributed. You could be cutting on a nice balmy day with a slightly dull chain (or some condition that has gotten the chain warm) and you have adjusted the chain for that condition - then you put your saw away in the barn and the temperature drops to 25 below. The chain could have gone through a temperature difference of 100 degrees or more - which could create a whole lot of tension on the chain.

 

[ropensaddle]

I don't know about the rest of you, but I have to adjust a time or two
in the day but never at the end. I have saws with many many hours on them, have not burnt the bearings yet! I do notice some people overtighten their chains,I run mine just snug.

 

[Lakeside53]

I don't automatically loosen my chain after every use - but I do make sure that there is just a bit of slack when I put them away in my heated basement. If the days cutting didn't provide some slack - then I will loosen the chain a bit.

I suppose the problem situation and the reason it is recommended to loosen the chain is that the Operators Manual has to account for every possible condition that your saw could experience - in all parts of the world that the saw is distributed. You could be cutting on a nice balmy day with a slightly dull chain (or some condition that has gotten the chain warm) and you have adjusted the chain for that condition - then you put your saw away in the barn and the temperature drops to 25 below. The chain could have gone through a temperature difference of 100 degrees or more - which could create a whole lot of tension on the chain.

But... The bar also contracts when the temp drops...

 

[spacemule]

But... The bar also contracts when the temp drops...

You seem to know a lot about things contracting.

 

[Zodiac45]

It certainly can't hurt, thats true. I've never done that to any of my saws and have never had any problems, but I tend to run a hair looser than tighter. But! On all of my stringed instruments, it's common practice too loosen the strings for storage of any length of time. Relieves stress on the neck.

 

[046]

sure I've adjusted a time or two in middle of the day. but I made sure bar/chain was cooled down before touching.

otherwise a new chain comes out, oiler checked out, etc. to find out why chain stretched out as to need adjusting.

please note, my chain is never tighten too much. chain has to move freely on bar, preferably with no sag. I might tighten a brand new chain a crack tighter on it's first use.

final tightening procedure is critical to chain maintaining it's tension.
what I'm referring to is pre-setting your bar's tilt.

BEFORE you tighten down bar nut(s). tighten chain taking out almost all chain sag, making sure chain still moves freely.

then with chain adjusted, bar tighten down, but still barely move. place your hand below bar, lift up taking out all tilt movement. then tighten bar nut(s) while supporting bottom of bar.

if you don't do this, no matter how tight your bar nuts are. Bar will tilt up loosening up chain tension. by the way... this is why some folks strip out bar nut studs.

I don't know about the rest of you, but I have to adjust a time or two
in the day but never at the end. I have saws with many many hours on them, have not burnt the bearings yet! I do notice some people overtighten their chains,I run mine just snug.

 

[oneoldbanjo]

Lakeside:

If the chain and the bar are the same temperature when you were running the saw and last tightened the chain - I suppose they pretty nearly expand and contract at the same rate as the air temperature changes when the saw is in storage. I don't know if the chain and bar both get hot at the same rate when they are being used. I had a really awful Mini Mac for a while and the manual oiler barely worked, and I seem to remember that as the chain got hot it got loose and when I tightened the hot chain while the bar was still relatively cool - the chain would get tight as it cooled off and transferred heat to the bar. I used the saw for cutting Honesuckle bushes that grow like weeds around here and the wood is very hard and really likes to pull chains off if they are a bit loose.

Under normal operatiing conditions I don't know if the chain and the bar stay the same temperature while they are being used. I do admit the difference should be pretty small.

 

[wood4heat]

I must be in opposite world, my chain gets tighter as I cut. After a little cutting I have to loosen my chain, after I've finished and it's cooled down the chain will literally be hanging off the bar. I tighten it before I use it again because I'm afraid it will come off it's so loose.