New bar and old chains... they don't go together!

[Rob D]

These are the obvious ones - but even slight damage seems to cause problems - this one was 'Cannon carving bars both in 10" and 12" on same saw getting very very hot. Saw oiling fine'.

 

You can see a ding in one part of the rim - this can be caused if you de rail a chain and then put it back on the bar, grease it up and force it to run. Because the drive rims get caught on the chain catcher and get burred and peened.

 

Much more subtle - and not sure of outcome yet ie. did dressing the bars/changing the rim and changing the chain sort it?

 

 

 

 

 

 

[Rob D]

In all the cases previous - changing the drive spur/rim and chain and bar sorted the problems [to my knowledge as didn't get confirmation in all cases]. So this then to me rules out any other causes you may think of.

 

Here's another:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

[Rob D]

Have a close look at your chains on your saws - are the under sides of the tie straps damaged? The drive links themselves?

 

It's the underside of the chain to look at not the top.

[Rob D]

9 minutes ago, Khriss said:

More importantly,  a rim sprocket exploding will bugger yr bearing on end of crank by jamming the chain in the side case, possibly ruining yr clutch also.  K

 

( basically it's neglect and penny pinching - that saw should be making you money hand over fist- if it ain't maybe a career in Arb is not fr you ) 

 

Yep - but I was equally guilty of above neglect when I was on the tools full time - it's only as I keep seeing people coming back asking ref warranty that I have seen a common problem. And getting pics and looking at them under the microscope figuratively speaking.

 

This is from home users and pros with 20 years under their belts.

 

It's a blind spot in the tool of our trade - you only have to look on this thread to see that - people are thinking all other reasons as to why bars fail. And they could be right - it could be a combo - but this area of not using old chains and old spurs/rims on a new bar is missed.

 

 

[Rob D]

Look at this chain - at a glance it's nearly new and looks fine - but it's not - if you look closely at the tie straps they are flattened which should not be anywhere close to this at this early stage:

 

[Rob D]

1 hour ago, MattyF said:

What sort of failures ? I have to be honest rob and think the sugi nose sprockets are to brittle , that is the only bar failure I’ve had and can’t see how that’s connected to worn drive sprockets.

 

Tolerances are tighter on the Sugi bars = more friction if anything is worn. Also the metal on the rails is harder so although over time they should last longer if they do get heated they suffer [oregon/husky/stihl do not take their rails as hard as Sugi or Tsumura and are more forgiving].

 

There is a direct correlation to bar failure [both on bar body and nose] to a worn drive rim or worn spur.

 

Sugi bars on less extreme worn chains and drive sprockets you tend to see chips  come out of the rail after a few months of use.

 

But that's not to say that caused the issues you may have had - it could well be a dud nose or a fault in the bearing... I'm saying that from what I have seen since taking over the calls and warranties the last 6 months there is a common element and none of the customers concerned have come back again with the same issue [again this is unconfirmed as I didn't call them to follow up].

 

 

 

 

[openspaceman]

1 hour ago, Rob D said:

 

 

This one strikes me as being caused by a worn drive link having peened a tie strap and making the joint too stiff to straighten as it comes off the sprocket. The original picture looked like blunt chain and too much pressure overheating the bar.

 

I would have liked to see the paint stripped off the bar to see how much of the blueing was caused by abuse and how much was from manufacture because some seemed to be at the groove bottom which might suggest a drive link bottoming out.

Edited August 19, 2020 by openspaceman
groovy spelling

[Rob D]

6 minutes ago, openspaceman said:

This one strikes me as being caused by a worn drive link having peened a tie strap and making the joint too stiff to straighten as it comes off the sprocket. The original picture looked like blunt chain and too much pressure overheating the bar.

 

I would have liked to see the paint stripped off the bar to see how much of the blueing was caused by abuse and how much was from manufacture because some seemed to be at the grove bottom which might suggest a drive link bottoming out.

 

The bar was pretty new so you would not have a drive link bottoming out. In pretty much all instances the bar is new or new ish hence I get called to ask about warranties.

 

The bar being forced to cut could well have been an issue - and also a slack chain - as the chain comes around the nose it slaps the bar just behind the nose sprocket.

 

 

 

[openspaceman]

2 minutes ago, Rob D said:

 

The bar was pretty new so you would not have a drive link bottoming out. In pretty much all instances the bar is new or new ish hence I get called to ask about warranties.

I take it you are referring to the your original picture here? I was considering why the blueing might be worse nearer the bottom of the bar groove, on the assumption that blue shows a higher temperature event than straw coloured.

2 minutes ago, Rob D said:

 

The bar being forced to cut could well have been an issue - and also a slack chain - as the chain comes around the nose it slaps the bar just behind the nose sprocket.

 

This too would explain the chipped nose in the picture I reposted.

[Rob D]

Almost forgot the 'best' picture of what a damaged or worn drive rim will do to the chain!