# Drive link damage when chains pop off modern saws



## Curlycherry1 (Dec 17, 2009)

Ok I understand technology moves forward since I bought my last chainsaw (Stihl 051AV) in 1980. I have a brand new MS660 and my friend has a new MS362. While working cutting the other day his chain popped off and he commented that a few of the drive teeth got damaged and did not fit back into the bar slot. I had never heard of such a thing and I cut firewood professionally trough the 1970s and early 1980s and had probably 1000+ chain pop offs. Even just the other day while working with my friend my chain popped off my 051 and I put it right back on with no problems.

Then while working with my friend with my saw the chain popped off and when I went to put it back on several of the drive teeth were damaged and would not fit back into the bar slot just like he had observed.

So what the heck is causing the damaged? My old saws never, and I mean never had a problem like this and so it has to be something causing it that was not part of the saws in the old days. My brother says it is that metal clip under the bar by the sprocket and he says rip the darn thing out!

So what is causing the damage and how to prevent it? I do not like the idea of having to do a 15 flat file service job on the drive teeth in the woods just to get my saw back up and running.


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## blsnelling (Dec 17, 2009)

It would be very foolish to remove the chain catcher. Besides, it's made of aluminum and would never damage a chain. All you have to do is dress the nick off the DLs and the chain will be fine. I would suspect that the higher chain speeds of todays saw might be a contributing factor. The same B&Cs on his new saws will fit on your 056, so it has nothing to do with the B&C.


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## volks-man (Dec 17, 2009)

i'm with snelling, file it to fit!
high speed is most likely a factor in the damage.


side note: not to challenge someone with experience such as yourself... but i've never had or even seen a chain pop off. are you running them just a tad loose?


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## Evan (Dec 17, 2009)

ive had a few come off. i had one come off my 372 32" bar a few damaged drive links wouldnt fit in the bar groove so i adjust the chain loose enough i could just turn it by hand , then fired up the saw and gave it a few carfull wots. 
this knocked the few burrs of the drive links probly put allitle exscesive wear on the inside of the bar groove but got it going in a pinch


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## sneno77 (Dec 17, 2009)

Not that uncommon for a chain to come off. Esp if you're cutting trees w/ small, tough limbs and using the top of your bar. One trick that was taught to me during my years on the thinning crew was to put the chain back on and leave it fairly loose. Rev the saw up and the burs are taken care of. Tighten it back up and you're back in business. I realize this isn't the safest option, but it's always worked for me and it's a heck of a lot quicker than trying to use a flat file in the woods.


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## oldsaw (Dec 17, 2009)

File the burrs off and run the chain. If it comes off again, you may have another problem such as a bent bar or the sprocket not lining up with the tail of the bar somehow. Put the bar down on your workbench and put a straightedge on top of it. Also make sure that the grooves are clear on the bar, especially at the tail.


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## taylor6400 (Dec 17, 2009)

volks-man said:


> i'm with snelling, file it to fit!
> high speed is most likely a factor in the damage.
> 
> 
> side note: not to challenge someone with experience such as yourself... but i've never had or even seen a chain pop off. are you running them just a tad loose?



Never? I have had it happen a few times, and yep, usually cutting small stuff that is in a sideways bind and it just pops it right off. I always went for the file, but its always been just a few links...no big deal. I always figured what nicked the teeth was the bar itself...not the chain catcher.


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## pinemartin (Dec 17, 2009)

To answer your question, on older saws the drive gear is generally a spur type where the teeth are ridged and run the full width of the gear. On a newer saw the drive gear is usually the rim and drum type where the rim has the ability to float from side to side. When a chain comes off these rim and drum systems there is the possibility it can push the rim to one side then ride on the splines of the drum until the saw is shut down. That is the cause of your problem and when shut down quickly the reason there are only a few drive links effected. PS the chain catch is innocent, so listen to Brad and keep the chain catcher on your saw for safety sake.


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## WoodChuck'r (Dec 17, 2009)

A couple of months ago my chain swung off my 7900 due to an idiot move in pinching my bar. The chain hit the chain catcher and the drive teeth (about 12 of them) were garred up pretty bad....

I just filed the edges with my raker file, took about 20 minutes but after that she was as good as new.


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## blsnelling (Dec 17, 2009)

I always though the nicks were wear the chain crossed over the bar rail.


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## barnumb (Dec 17, 2009)

The chain catcher stops the chain immediately and the drive sprocket keeps moving and consequently damages the chain. I have seen this on both drive styles. On my husky 66 if the chain comes off you are filing down torn up drivers. A roller chain catcher seems to help.


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## Curlycherry1 (Dec 17, 2009)

volks-man said:


> side note: not to challenge someone with experience such as yourself... but i've never had or even seen a chain pop off. are you running them just a tad loose?



It popped off cutting some small brush, less than an inch in diameter. That is typically when it has always happened with me. Something in the pile catches it just right and off it goes. 

I do probably run a saw chain about 1/8 turn looser than some folks. It comes from what I was taught and what my brother has observed over thousands of cords run on his processor. He has seen that a tight chain wears the bar down faster than if you just back it off 1/8 turn. He of course does not have pop off problems because he never cuts anything but straight cuts.


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## Curlycherry1 (Dec 17, 2009)

oldsaw said:


> File the burrs off and run the chain. If it comes off again, you may have another problem such as a bent bar or the sprocket not lining up with the tail of the bar somehow. Put the bar down on your workbench and put a straightedge on top of it. Also make sure that the grooves are clear on the bar, especially at the tail.



Its a brand spanking new saw with 1.5 tanks of gas in it, but just to be sure I put a machinist's straightedge up against the bar while I had it in the shop. I always check my bars for flat when I get the chance to to check them. When I went to get a bar at the local Stihl shop the first one I picked off the rack had a 1/8" gap in the middle as I set it on the bench to pay for it. And it was still in the box! I took it out, laid it down and told the guy he had a problem and he agreed. I got another bar off the rack and it was fine.


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## pinemartin (Dec 17, 2009)

blsnelling said:


> I always though the nicks were wear the chain crossed over the bar rail.



I always thought the nicks were where the chain catcher stopped the chain and the splines on the drum flattened the face of the drive links. If it did happen when a chain crossed over the bar rail you would see this happen on all saws not just the ones with drive rims..


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## blsnelling (Dec 17, 2009)

I've not seen the face of the DL flattened. They were always nicks on the sides.


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## Curlycherry1 (Dec 17, 2009)

Evan said:


> ive had a few come off. i had one come off my 372 32" bar a few damaged drive links wouldnt fit in the bar groove so i adjust the chain loose enough i could just turn it by hand , then fired up the saw and gave it a few carfull wots.
> this knocked the few burrs of the drive links probly put allitle exscesive wear on the inside of the bar groove but got it going in a pinch



I'll confess, that is what I did. Where do I go to get my chainsaw abuser flogging? One quick spin and it dropped right into the track. A few revs and it was warmed up enough to get the perfect tension that I like to have. Adjusting tension on a cold chain is something I do not like to do because once warmed, it often is too loose.

Rant mode on: That chain catch under the bar is a useless part. I already said I had probably over a thousand pop off over my career but never so much as once did I ever have the chain contact my leg, ever. I would love to see any stats that show that was an actual problem.

Kind of like when I was the safety enforcer for my building at work. One day the fire marshall demands all solvent cabinets have self-closing doors. I then pointed out that in over several hundred monthly safety inspections there NEVER was a single case of the doors being cited from being open. Yet the company nurse had something like 18 incident reports of people getting gonked up side the head from cabinets with self-closing doors where their hands slipped and the door closed just as they were looking into the cabinet. Several folks had to get stiches because the lip on the door seal was sharp. That did not deter them and so we had to replace every non-self-closing cabinet, and I got two nice ones for home use for dirt cheap. 

I just have a suspision that this 'safety feature' is causing more problems than it is solving.


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## blsnelling (Dec 17, 2009)

Curlycherry1 said:


> Rant mode on: That chain catch under the bar is a useless part. I already said I had probably over a thousand pop off over my career but never so much as once did I ever have the chain contact my leg, ever. I would love to see any stats that show that was an actual problem.



Sounds like a good way to destroy a case or tank/handle. Chain catchers are cheap. Why not use them? Have you ever seen how mangled they can get from catching one chain? That energy has to go somewhere. Why not let if be absorbed by a cheap, inexpensive, replaceable part?


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## pinemartin (Dec 17, 2009)

IT IS NOT THE CHAIN CATCHER DAMAGING YOUR DRIVE LINKS. It is aluminum and only hits the front of the drive links, they are always damaged on the curved back side when the splines of the drum flatten them out. I have slow motion footage of this being the only cause. I don't mean to yell but the chain catcher is innocent.


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## bitzer (Dec 17, 2009)

Chain catchers are there to catch the chain. I think they do mess up the chain on occasions tho. Its metal to metal contact, it doesn't matter how soft the aluminum is. I don't throw chains often, but I've had some flat DL fronts and plenty of swells on the sides. I do like the roller chain catcher for the dual dawgs. It keeps the chain farther out. I've had them slap me in the leg several times, but no injuries. 


The easiest way to throw a chain are on what I call "chain skippers," Saplings and small stuff under 5" or so. You cut threw them and they like to push your chain out of the rails if you don't let off on the throttle before you get that far.

I also think the spur type sprockets throw chains more easily than rim. Much more side to side movement. 

File off the burs and run them. It sounds like the OP is running chains a little loose, throwing them all the time like that.


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## Curlycherry1 (Dec 17, 2009)

blsnelling said:


> Sounds like a good way to destroy a case or tank/handle. Chain catchers are cheap. Why not use them? Have you ever seen how mangled they can get from catching one chain? That energy has to go somewhere. Why not let if be absorbed by a cheap, inexpensive, replaceable part?



Like I said I would love to see the evidence that it actually does any good. Looking at my old 051AV I see no knicks in the cover where the chain would catch when it pops off. That saw has easily 2000+ face cords of wood it has eaten along with well over 2000 lumber log drop and tops. It has probably 5-600 pop offs in its career. Zero damage from chains hitting that part of the cover. 

I see on my 660 they have a rubber bumper in the cover in that region to protect the back of the saw should the chain pop off.

I'll leave the chain catch on but I am just not buying it that it is not causing more problems than it is fixing. As a scientist I do see an experiment coming where I might record what happens with it on and then take it off just to see if there really is damage. I just can't let things like this bug me without it being proven to me.


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## bitzer (Dec 17, 2009)

pinemartin said:


> IT IS NOT THE CHAIN CATCHER DAMAGING YOUR DRIVE LINKS. It is aluminum and only hits the front of the drive links, they are always damaged on the curved back side when the splines of the drum flatten them out. I have slow motion footage of this being the only cause. I don't mean to yell but the chain catcher is innocent.



They are not always damaged on the curved back side. I'd like to see the footage tho! It would be an interesting add to this thread!


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## Curlycherry1 (Dec 17, 2009)

bitzercreek1 said:


> File off the burs and run them. It sounds like the OP is running chains a little loose, throwing them all the time like that.



I had a lot, and I do mean a lot of handle bar time on my saws back when I cut and sold firewood. By the sheer number of hours I cut I had more stuff happen than a lot of folks typically do. And I admit I run my chains just a bit (1/8 turn) looser than recommended,and when I get cutting brush the chain pops off sometimes. It is not a big deal to me because I have never had damage happen before. 

As the shop I got my saws serviced said to me one day "rub your right hand hard across the counter top 20 times and then run your left hand across it lightly 20 times. Which hand is cooler? Before that point I would get a few months out of a bar before it was shot, after than I never bought a bar for my saw and that bar is still on my saw to this day.


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## Curlycherry1 (Dec 17, 2009)

pinemartin said:


> IT IS NOT THE CHAIN CATCHER DAMAGING YOUR DRIVE LINKS. It is aluminum and only hits the front of the drive links, they are always damaged on the curved back side when the splines of the drum flatten them out. I have slow motion footage of this being the only cause. I don't mean to yell but the chain catcher is innocent.



Ahhh but if the chain could pop out of the drive sprocket would the damage not occur? Seem to me the chain pops off, catches on the catch and then from that point to the sprocket the sprocket removes all slack in the chain. Now with the chain held tight between the catch and the slots in the sprocket, the only thing that can happen is the sprocket digs into the drivers of the chain, thus denting them.

Now if he chain had slack it would pop right out of the drive sprocket before any damage could be imparted on the drive links.

I have alot of brush to cut with my friend so I am seeing an experiment brewing in my head.


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## pinemartin (Dec 17, 2009)

Curlycherry1 said:


> Ahhh but if the chain could pop out of the drive sprocket would the damage not occur? Seem to me the chain pops off, catches on the catch and then from that point to the sprocket the sprocket removes all slack in the chain. Now with the chain held tight between the catch and the slots in the sprocket, the only thing that can happen is the sprocket digs into the drivers of the chain, thus denting them.
> 
> Now if he chain had slack it would pop right out of the drive sprocket before any damage could be imparted on the drive links.
> 
> I have alot of brush to cut with my friend so I am seeing an experiment brewing in my head.



Good! take a few extra chains a flat file and a torks wrench to take off the chain catch and a camera...


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## bitzer (Dec 17, 2009)

Curlycherry1 said:


> I had a lot, and I do mean a lot of handle bar time on my saws back when I cut and sold firewood. By the sheer number of hours I cut I had more stuff happen than a lot of folks typically do. And I admit I run my chains just a bit (1/8 turn) looser than recommended,and when I get cutting brush the chain pops off sometimes. It is not a big deal to me because I have never had damage happen before.
> 
> As the shop I got my saws serviced said to me one day "rub your right hand hard across the counter top 20 times and then run your left hand across it lightly 20 times. Which hand is cooler? Before that point I would get a few months out of a bar before it was shot, after than I never bought a bar for my saw and that bar is still on my saw to this day.



I get what your saying. I don't run them that tight either tho, I just keep an eye on them and make sure they aren't slacking more than they should and oiling well. I spend at least a cummulative of four months out of the year felling, bucking, and limbing. I am not in production, but I do mostly land clearings that get used or sold as firewood and occaisonally a good saw log for lumber. I don't know how many how many hundreds or even thousands of hours I have running saws, but it seems like the op and his friend are throwing a lot of chains. How long have you had that last bar?


Whoops! Didn't realize you are the OP. Are you adjusting for stretch? Chains say they are pre-stretched, but they still stretch.


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## blsnelling (Dec 17, 2009)

Curlycherry1 said:


> Like I said I would love to see the evidence that it actually does any good. Looking at my old 051AV I see no knicks in the cover where the chain would catch when it pops off. That saw has easily 2000+ face cords of wood it has eaten along with well over 2000 lumber log drop and tops. It has probably 5-600 pop offs in its career. Zero damage from chains hitting that part of the cover.



I've seen plenty of damage caused to saws by thrown chains. Holes in tanks, broken cases, broken clutch covers....


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## Justsaws (Dec 17, 2009)

Curlycherry1 said:


> It popped off cutting some small brush, less than an inch in diameter. That is typically when it has always happened with me. Something in the pile catches it just right and off it goes.
> QUOTE]
> 
> Tighten up the chain. Are you stacking and slashing?


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## 2dogs (Dec 17, 2009)

blsnelling said:


> I've seen plenty of damage caused to saws by thrown chains. Holes in tanks, broken cases, broken clutch covers....



Yep. The chain catcher saves the saw. It is intended to be an ablative shield and absorb the energy from a thrown chain. Still if you don't like having one then take it off. Just don't expect to work for me. BTW the chain brake handle gets in the way too.


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## bitzer (Dec 17, 2009)

blsnelling said:


> I've seen plenty of damage caused to saws by thrown chains. Holes in tanks, broken cases, broken clutch covers....



:agree2: I bought a fleabay Stihl 044 once. I couldn't tell from the pics, but when I got it, everything inside the clutch cover and including the cover were destroyed. The catcher was gone except for the plate holding it to the case. The covers over the brake band were toast. The metal clutch cover had cracks and nicks and the studs that held the rubber insert at the back of the cover were completely gone. The guy left the saw in his truck often and didn't have any tools to tighten the chain I came to find out. He threw chains often apparently. Also the metal fuel tank guard behind the clutch cover was toast. If the guard had not been there I am sure there would have been a hole in the fuel tank.


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## Grande Dog (Dec 17, 2009)

Howdy,
Damage to the drive links can happen whether your running a spur, or a rim. It's just a mater of luck. With bad luck, when the chain comes off it stacks a loose loop around the sprocket. The sprocket will beat about 6-10 drive links pretty good.
Regards
Gregg


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## barnumb (Dec 17, 2009)

Grande Dog said:


> Howdy,
> Damage to the drive links can happen whether your running a spur, or a rim. It's just a mater of luck. With bad luck, when the chain comes off it stacks a loose loop around the sprocket. The sprocket will beat about 6-10 drive links pretty good.
> Regards
> Gregg



Bingo!


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## Curlycherry1 (Dec 17, 2009)

blsnelling said:


> I've seen plenty of damage caused to saws by thrown chains. Holes in tanks, broken cases, broken clutch covers....



That is interesting because I have never been touched by a saw chain coming off and I have never seen any damage due to a chain coming off. Keep in mind though I am working with a knowledge base that is a few decades in the past. From 1984 though to just recently I did virtually no cutting. From about 1973 to 1984 I lived with a saw in my hands. And my 051 is one of them old beasts made out of metal. Not all this aluminum and plastic like the new saws. Of course at ~25#+ I know what it is made out of every time I pick the darn thing up.


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## CGC4200 (Dec 17, 2009)

*drive link damage*

I have seen this twice this fall, once on a saw I have with a rim
sprocket & the other on a friends saw with a spur. They were both new
chains still stretching/breaking in. I ground off the burs with a grinder
bit in a dremel type tool to fix. I was blaming chain catcher, but after
reading this thread, I agree that still spinning sprocket was probably
to blame. In my case I probably kept saw WOT a fraction of a second
before noticing something was not right.


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## smitty299 (Dec 17, 2009)

I don't understand how anybody could blame the chain catcher it cant even touch the drivers its on the outside of the loop where the cutters are


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## wigglesworth (Dec 17, 2009)

Curlycherry1 said:


> I had never heard of such a thing and I cut firewood professionally trough the 1970s and early 1980s and had probably 1000+ chain pop offs.





Curlycherry1 said:


> It has probably 5-600 pop offs in its career. Zero damage from chains hitting that part of the cover.





Curlycherry1 said:


> I do probably run a saw chain about 1/8 turn looser than some folks. It comes from what I was taught



So your saying that you have had over 1,000 chain derailments in your career. It sounds like that "1/8 looser" is biting you in the butt. LOL


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## wheelman (Dec 17, 2009)

smitty299 said:


> I don't understand how anybody could blame the chain catcher it cant even touch the drivers its on the outside of the loop where the cutters are



I am with Smitty


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## Curlycherry1 (Dec 17, 2009)

wigglesworth said:


> So your saying that you have had over 1,000 chain derailments in your career. It sounds like that "1/8 looser" is biting you in the butt. LOL



I would rather have a pop off or two and have my bars last a lot longer. I am using the tension the mfg rep suggested for my brother's wood processor and that runs 3-4 cuts per minute, 8-12 hours/day, 6 days per week and bars last almost 6 months. When he tensioned tight as recommended by the chain manufacturer, they lasted about 1.5-2 months. Friction is bad for any two metal surfaces that rub together, and more friction makes metal heat up and wear down faster. There is a fine line between being tight enough to work, and too tight to cause premature wear.

As I said I have never had a problem with chain pop off being an issue. Put them back on and go. Now with the damage I am seeing I should take the chain off, file the damage away and put it back on. If I were in production, that is wasted time and time = money.


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## wigglesworth (Dec 17, 2009)

Curlycherry1 said:


> I would rather have a pop off or two and have my bars last a lot longer. I am using the tension the mfg rep suggested for my brother's wood processor and that runs 3-4 cuts per minute, 8-12 hours/day, 6 days per week and bars last almost 6 months. When he tensioned tight as recommended by the chain manufacturer, they lasted about 1.5-2 months. Friction is bad for any two metal surfaces that rub together, and more friction makes metal heat up and wear down faster. There is a fine line between being tight enough to work, and too tight to cause premature wear.
> 
> As I said I have never had a problem with chain pop off being an issue. Put them back on and go. Now with the damage I am seeing I should take the chain off, file the damage away and put it back on. If I were in production, that is wasted time and time = money.



Chain pop off is a pretty big issue, most especially if it has happened to you thousands of times. Besides that, it damages the drivers  I have had a chain pop off on me 1 time in my small amount of time behind a saw, and it was an old hardnose bar running the chain too loose and pinched the bar tip in a cut. Simply put, I would *think* it is hard to pop a chain off if everything was tightened properly.


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## wigglesworth (Dec 17, 2009)

Straight from the oregon site...



> For a sprocket nose bar, turn your saw's tension-adjustment screw until the bottoms of the lowest tie straps and cutters come up and contact the bottom of the bar rails, then turn your tension-adjustment screw an additional 1/4 turn. Also, on sprocket nose bars, the snap test should be performed. Grasp the chain along the bottom of the bar, pull down, and let go. The chain should snap back to its original position, solidly contacting the bottom of the bar rail.
> 
> 
> For a solid-nose bar, turn your saw's tension-adjustment screw until the bottoms of the lowest tie straps and cutters come up and contact the bottom of the bar rails. Chain tension on a solid-nose bar should be adjusted looser than on sprocket nose bars. Regardless of your bar type, your chain should move freely around the bar.
> NEVER TENSION CUTTING CHAIN WHILE IT'S HOT!


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## Curlycherry1 (Dec 17, 2009)

wigglesworth said:


> Simply put, I would *think* it is hard to pop a chain off if everything was tightened properly.



A loose to even slightly loose chain being swung around in brush and small stuff and it can pop off fairly easy. Keep in mind that what I used to do was not the weekend warrier poking around in the woods. I was in full production mode and so slashing and trashing of brush and tops was common. Just get the junk out of the way as fast a possible so as to get to the wood that needed to be cut was priority #1. Not always safe by some standards, but I was young and needed to get wood out.


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## Curlycherry1 (Dec 17, 2009)

> For a sprocket nose bar, turn your saw's tension-adjustment screw until the bottoms of the lowest tie straps and cutters come up and contact the bottom of the bar rails, then turn your tension-adjustment screw an additional 1/4 turn.



I use 1/8 turn and not 1/4. I guess when I cut brush and these small things I am currently working on I should tweak it up that full 1/4. I have never cut this much brush before. I am helping a friend clear the lot for building a house and we need it clean for layout and planning. If it were a real job those twigs would be ignored and driven right over with the tractor or skidder. They would never even be given a second thought.


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## J.W Younger (Dec 17, 2009)

Curlycherry1 said:


> I'll confess, that is what I did. Where do I go to get my chainsaw abuser flogging? One quick spin and it dropped right into the track. A few revs and it was warmed up enough to get the perfect tension that I like to have. Adjusting tension on a cold chain is something I do not like to do because once warmed, it often is too loose.
> 
> Rant mode on: That chain catch under the bar is a useless part. I already said I had probably over a thousand pop off over my career but never so much as once did I ever have the chain contact my leg, ever. I would love to see any stats that show that was an actual problem.
> 
> ...


keep in mind tank assemblys are no easy piece to find used and expensive new.With no chain catcher you will eat up a gas tank pretty fast if you toss a lot of chains


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## Steve NW WI (Dec 17, 2009)

Here's some tossed chain carnage for you, 261 Olympik clutch cover with most of the bottom broken off.

Most of the cover's I've found on Ebay, etc for this saw look the same way, so it may be a weak spot in the design, but damage from a thrown chain nonetheless.


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## davec (Dec 17, 2009)

bitzercreek1 said:


> I don't know how many how many hundreds or even thousands of hours I have running saws, but it seems like the op and his friend are throwing a lot of chains. How long have you had that last bar?
> 
> 
> Whoops! Didn't realize you are the OP. Are you adjusting for stretch? Chains say they are pre-stretched, but they still stretch.



I'm the other half of the Chain Throwers Anon support group. But it's only happened once so far.  I'm new to chainsaws, but been around a lot of other professional power tools for years, so I'm not unaccustomed to the Way of The Tool, just not chainsaws. I threw one chain last weekend - my first. Ever. It was a new chain, and I had tensioned it before use, but should have been watching the tension more closely as it was brand new (something I knew from reading here, but didn't apply well enough). It was on a small 1-2" tree that was in a mess of other stuff that I had thought was going to be a potential pinch hazard, but it still had to be cut. Well it got cut and pinched the chain and threw it. That was when I found the issue with driver dings and I didn't have a backup chain with me (another lesson). New to me, of course. Reasons it happened: 1. probably too little tension after a bit of use on a new chain. 2. small tree/pinch grab etc. I'll work on better tensioning now 

But the question my friend the OP has is still a legitimate one. Does the chain catcher contribute to this damage? I am a big advocate of safety gear, but I also know that liability concerns can drive companies to do things at times that are safety related but are not really worth the trouble they cause. Being new to all this, I'm asking the same question. Sounds like several of you are saying without it, especially on the new saws with their much higher rpms, you risk at least severe saw damage and possibly injury. Makes sense. But just asking the question is not a bad thing, now is it? 

Now it's almost Sat, so I get to try it again, learning from last week... 


-Dave


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## Curlycherry1 (Dec 17, 2009)

Steve NW WI said:


> Here's some tossed chain carnage for you, 261 Olympik clutch cover with most of the bottom broken off.
> 
> Most of the cover's I've found on Ebay, etc for this saw look the same way, so it may be a weak spot in the design, but damage from a thrown chain nonetheless.



I am not trying to be difficult here, but I have seen that kind of damage on a few saws and I can say in all the cases that I saw it (on Homelites) I knew for 100% certainty what caused it (see below). 

Now that said, how can the side of the cover break off if the chain is being thrown off the bar? How can a chain develop that much side force to crack and break that metal? The forces of a chain coming off is exactly parallel and in alignment with the axis of the bar. So damage shold be behind the bar under the saw. I find it hard to believe that a chain could jump off the track, swing over ~3/4-1" and break off that much metal.

I do know with my old Homelites if they got banged around in the back of a truck with a peavey or a splitting maul or two, then those covers snapped right off like twigs and the damage would look just about like that. Or if they got dropped on their side onto any kind of hard surface. Of course I never did that to my saws, no never did that, no personal experience here.


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## Steve NW WI (Dec 17, 2009)

CC, the pic I posted is off a project saw torn apart in the basement. This weekend I'll get a pic of my 271, fully assembled. I can assure you that that chain cover looks similar to the one in my pic, and that the chain caused it, because it happened while SOMEONE (who shall remain nameless) was using it.

Think on this, your straight line logic doesn't hold water. If the chain were still traveling in a straight line, inline with the bar, it would still be ON the bar, not tossed. Every chain I've tossed has come off the bar and wound up at the powerhead, not off the powerhead and still on the bar. That energy is hitting something, and I'll guess that magnesium will be more brittle with age, as aluminum does, and voila' broken clutch cover.

IIRC, the chain catcher on these was mounted to the side cover, which would be a good bit weaker than if mounted to the engine. This could be a contributing factor here.

On the original subject, I'm in the higher chain speed train of thought. I never had a damaged drive link on the older slower saws, and the first time it happened to me was on my 7300 Dolmar. I just swapped chains, and dressed up the dinged chain with a light sanding from a die grinder with a sanding pad on it.


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## Curlycherry1 (Dec 17, 2009)

Steve NW WI said:


> Think on this, your straight line logic doesn't hold water. If the chain were still traveling in a straight line, inline with the bar, it would still be ON the bar, not tossed. Every chain I've tossed has come off the bar and wound up at the powerhead, not off the powerhead and still on the bar. That energy is hitting something, and I'll guess that magnesium will be more brittle with age, as aluminum does, and voila' broken clutch cover.



Your logic makes sense and I was not thinking that once it was popped then it would travel in the opposite way it was pushed off the bar. Makes sense. 

And if your nameless friend can vouch for that damage then I guess we can trust him. 

The old Homelite XL12s and 925s that I used had covers that were so brittle it was amazing they lasted at all. I dropped one on a concrete floor once in my basement while putting a new chain on and the cover shattered like glass.  They also seemed to get a lot of damage, especially cracks, from being tossed onto the top of a load of wood at the end of the day. I would nestle them down between some blocks so the saws would not come off but the wood would pinch the cover and do damage. When I assembled my large truck for hauling I put a slot in the rack right behind the cab so I could stick the saw bar down into the slot and the powerhead was at the top of the woodpile and in front of the entire load. The saws got far less damage up there and I did not have to get them off the wood before dumping it.


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## davec (Dec 18, 2009)

> The old Homelite XL12s and 925s that I used had covers that were so brittle it was amazing they lasted at all. I dropped one on a concrete floor once in my basement while putting a new chain on and the cover shattered like glass.



Sounds like cast aluminum... badly cast alum. Aluminum does not cast well, especially if you are not midful of the process. Lots of porosity and inclusions that make it weak. But forge it or do something like hot rolling or pressing and it improves greatly.


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## bitzer (Dec 18, 2009)

smitty299 said:


> I don't understand how anybody could blame the chain catcher it cant even touch the drivers its on the outside of the loop where the cutters are




How long of bars do you run? The chain will swing around and get tangled up and kinked an all kinds of messed up stuff. I would say most of the dl damage is the sprocket, but there is a lot going on. It depends on where the chain skips off the bar as well.


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## bitzer (Dec 18, 2009)

davec said:


> I'm the other half of the Chain Throwers Anon support group. But it's only happened once so far.  I'm new to chainsaws, but been around a lot of other professional power tools for years, so I'm not unaccustomed to the Way of The Tool, just not chainsaws. I threw one chain last weekend - my first. Ever. It was a new chain, and I had tensioned it before use, but should have been watching the tension more closely as it was brand new (something I knew from reading here, but didn't apply well enough). It was on a small 1-2" tree that was in a mess of other stuff that I had thought was going to be a potential pinch hazard, but it still had to be cut. Well it got cut and pinched the chain and threw it. That was when I found the issue with driver dings and I didn't have a backup chain with me (another lesson). New to me, of course. Reasons it happened: 1. probably too little tension after a bit of use on a new chain. 2. small tree/pinch grab etc. I'll work on better tensioning now
> 
> But the question my friend the OP has is still a legitimate one. Does the chain catcher contribute to this damage? I am a big advocate of safety gear, but I also know that liability concerns can drive companies to do things at times that are safety related but are not really worth the trouble they cause. Being new to all this, I'm asking the same question. Sounds like several of you are saying without it, especially on the new saws with their much higher rpms, you risk at least severe saw damage and possibly injury. Makes sense. But just asking the question is not a bad thing, now is it?
> 
> ...



You are right asking the question is not a bad thing at all. Those saplings are the worst for throwing chains, that and limbing under pressure. When you cut through a sapling they like to slide off and take your chain off with it if you don't let off on the throttle or are not on top of it. The catcher is there for good reason. I would use it regardless if it mess the chain up or not.


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## slowp (Dec 18, 2009)

Hmmm. This explains my puzzlement a bit. When I ran a saw on a thinning crew, I was the newby and got the last pick of the saws. The one that I finally ended up running would only run with the chain loose. The saw threw off the chain at least a couple times a day, but no problem, I just slapped it back on and went back to work. That was a 1970 something Mac. 

Flash forward to the now. I'v thrown chains on the Barbie Saw and Twinkle. Each time, the drive things were damaged and I had to file them down. The worst one I had to put on reading glasses and use the Dremel to repair. 

Twinkle threw a chain one day that thumped me in the thigh pretty good. It missed my chaps but hit the rivet on my Carhartts. No cut, just some inefficient language and a little bruise. Wouldn't you know, there was an audience too?


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## MCW (Dec 18, 2009)

pinemartin said:


> To answer your question, on older saws the drive gear is generally a spur type where the teeth are ridged and run the full width of the gear. On a newer saw the drive gear is usually the rim and drum type where the rim has the ability to float from side to side. When a chain comes off these rim and drum systems there is the possibility it can push the rim to one side then ride on the splines of the drum until the saw is shut down. That is the cause of your problem and when shut down quickly the reason there are only a few drive links effected. PS the chain catch is innocent, so listen to Brad and keep the chain catcher on your saw for safety sake.



I agree. I've had the chain stop solid on the catcher and the damage is caused by the sprocket. Rim sprockets in my experience do tend to cause more damage with a thrown chain but my spur sprocket saw experience is limited to smaller saws with 3/8"LP and gutless 029's.
I just think a rim sprocket has a lot better purchase on the drive links hence more damage when something goes wrong.


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## McLeach (Jan 8, 2023)

Figured I'd post a picture of drive link damage, cause everyone needs pics in their life. 

As a side note. This chain is off the homemade chainsaw. I did the build thread on here. What I can say, is that the chain never came off. Derailed, or any of that. It ran great until it ceased itself in the bar. 

It's possible it could have been caused by no oil. It ran out way faster than I expected, plus I didn't realize that tipping the saw over with the clutch facing up, to inspect it, was draining the oil back through the exhaust tube. (Oil is run by exhaust pressure) It was a learning experience. The saw is made to side cut clutch down anyway.

The main factor that caused the damage, I believe, is mostly being the narrower gage drivers. Its .404/.058 on a 15 hp saw. 10 tooth rim sprocket. I dressed the links back down and will give it another shot.


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## singinwoodwackr (Jan 8, 2023)

McLeach said:


> Figured I'd post a picture of drive link damage, cause everyone needs pics in their life.
> 
> As a side note. This chain is off the homemade chainsaw. I did the build thread on here. What I can say, is that the chain never came off. Derailed, or any of that. It ran great until it ceased itself in the bar.
> 
> ...


I would think .063 would be better for that saw anyway.
cool build? 
have you inquired on the hotsaw page about special chain that might better handle the higher rpms ?


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