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

[MattyF]

 
Yep well it's personal choice how you run your gear but best practice is to change the drive rim and sprocket regularly as it leads to premature damage. Stihl and Oregon say you should, I say you should as I've seen the damage caused by not doing it - but it's a forum and things are up for debate... I see 2 to 3 bar failures a week and there is a common theme in what I believe has caused the damage in most cases.
 
 
 

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.

[Rob D]

1 hour ago, Stubby said:

Also its clear the bar has never been flipped . They do work with the writing upside down ! .

I don't think this was ever used long enough to flip it ie. damage done within 1 hour of using it..

[Rob D]

I do have some science to back up my conclusions and have been meaning to make a vid for a long time on this.I'm not saying I am right or wrong but if you approach this topic with an open mind.

 

As a rule of thumb:

1. Worn drive spur or rim
2. Worn chain
3. Worn bar

The above combo sort of works - it doesn't work like it should but it works.

 

• Change the chain [and keep old drive spur/rim and bar] - you'll have no issues - the worn drive sprocket peens the sides of the drive links but the bar groove is already worn wider by the last chain.
• Change the drive spur or rim [and keep old bar and chain] - you'll have no issues [that you'll notice] - the worn chain will wear the new drive spur/rim much much faster but you won't see anything
• Change the bar [and keep old drive spur/rim and old chain] - new bar [particularly the Japanese and Cannon bars] the rails are harder and the tolerances are tighter. The drive links on your chain are peened which makes them wider - they just about still fit but the friction especially on running it up is severe. Worst case it heats the bar massively and it's obvious something is wrong. Next worse case it heats the bar up a fair bit but sort of works but 2 or 3 weeks down the line a chip appears in the bar where the metal has got hot and become brittle.

 

 

[Rob D]

[Rob D]

If you check the above pic look at how [on the tie straps] the drive spur has got worn and is now pushing up into the tie straps and burring them over. This creates sharp metal where it should be smooth. These wear the bar on the top rail and create friction - so they get peened, go round the bar and drive sprocket, back round the spur and get peened again etc..

[Rob D]

All these examples are customers who came back after changing over to a new bar [and having issues straight away] but using the old chains and drive spur/rim.

 

 

 

 

 

 

 

 

[Rob D]

 

 

 

 

 

 

 

[Rob D]

 

 

 

[Rob D]

I have I think x18 or so examples - it's quite hard to collate and get pics off people...

 

All came saying they had premature bar failure, bar oiling was fine and they tested it with the bar off and they said oil hole was free [got no way to test this though..].

 

Mixture of bars effected from all main manufacturers but Sugi seem the most effected [but then that's what we sell most of].

[Khriss]

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 ) 

Edited August 19, 2020 by Khriss