Why did this happen?

[Woodworks]

1 hour ago, Ratman said:

I know nowt about processors but presumably you’ll resharpen chains etc as you would with a chainsaw. The wear on the sprocket is not central compared with the new one (meaning early stages of wear as opposed to the later where you have seen the chain ride sideways)
You got any broken/fractured links on your chain? This along with tension and pulling through the wood could cause the chain to deviate off centre.

 

The processor is no different to a Stihl saw really in that you have a sprocket floating on a spline so self-centers or should do. 

 

Will look to see if any of my chains have a damaged link but they have all been cutting fine up until the other morning when this all happened.  

[arboriculturist]

Less likely to be a single chain that caused this as due to nature of processing you change multiple chains rather than sharpen.  Bar check - done. Are you sure Bar rails are same height using a square especially at sprocket end? Have you checked sprocket Internal fit? How does it compare with the new one? Does it rock more? Are you sure bearing is 100% serviceable? 

[billpierce]

I think there is a chance the last chain you fitted wasnt on the sprocket proper and has been tension up running on the edge of the sprocket. I assume this has only happened once?

If you chain drive links generally look good with the exception of the one that came off it as you notice this sprocket I would say that's the bother.

[Woodworks]

1 hour ago, arboriculturist said:

Less likely to be a single chain that caused this as due to nature of processing you change multiple chains rather than sharpen.  Bar check - done. Are you sure Bar rails are same height using a square especially at sprocket end? Have you checked sprocket Internal fit? How does it compare with the new one? Does it rock more? Are you sure bearing is 100% serviceable? 

The underside of the bar is spot on but the fillet that sits on the top of the bar was out of square for the first few cm. Squared it up now. Not sure if this could have been the cause but something has brought this about. Bearing feels fine and no noticeable play or roughness 

[Woodworks]

15 minutes ago, billpierce said:

I think there is a chance the last chain you fitted wasnt on the sprocket proper and has been tension up running on the edge of the sprocket. I assume this has only happened once?

If you chain drive links generally look good with the exception of the one that came off it as you notice this sprocket I would say that's the bother.

2

Don't think you can get it to seat anywhere other than in the middle.

[woodwizzard]

Is there an inner and outer face of the sprocket, as in spaced out further if fitted on one way or the other?

[Woodworks]

19 minutes ago, woodwizzard said:

Is there an inner and outer face of the sprocket, as in spaced out further if fitted on one way or the other?

No, they are pretty much symmetrical (when new) and I swap them around from time to time.

[arboriculturist]

51 minutes ago, Woodworks said:

No, they are pretty much symmetrical (when new) and I swap them around from time to time.

I would fit the new one and a new chain, then closely monitor for evenness of wear.

If Spud sees this post he will probable diagnose the issue.

[spudulike]

Not really my thing but it looks like the chain has been jumping over the rim. The fella that said he reckoned the chain had be tensioned with the chain riding on the very edge of the rim is the most likely explanation and it would have dropped back in to the centre of the rim but be well under tension then it slipped round the rim.

Fit a new rim and chain then see how it goes. 

[ESS]

Not familiar with processor bars/chains , but.. has it run a chain that has had rakers lower at one side? that would kick the chain over.