Drive link damage when chains pop off modern saws

[bitzer]

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!

 

[Curlycherry1]

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.

 

[Curlycherry1]

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.

 

[pinemartin]

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...

 

[bitzer]

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.

 

[blsnelling]

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....

 

[Justsaws]

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?

 

[2dogs]

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.

 

[bitzer]

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.

 

[Grande Dog]

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

 

[barnumb]

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!

 

[Curlycherry1]

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.

 

[CGC4200]

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.

 

[smitty299]

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

 

[wigglesworth]

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.

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

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

 

[wheelman]

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

 

[Curlycherry1]

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.

 

[wigglesworth]

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.

 

[wigglesworth]

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!

 

[Curlycherry1]

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.