Why did this happen?

[Woodworks]

This is the drive sprocket off our processor and a new one for comparison. They normally wear down evenly in the middle and last ages. This one was fine until a short while ago and then all of a sudden the chain kept wanting to run on one side of the sprocket and wrecked it in no time. They cost £70 each so it would be nice to know what was the cause before putting it back on the processor. Thanks

[Stubby]

26 minutes ago, Woodworks said:

This is the drive sprocket off our processor and a new one for comparison. They normally wear down evenly in the middle and last ages. This one was fine until a short while ago and then all of a sudden the chain kept wanting to run on one side of the sprocket and wrecked it in no time. They cost £70 each so it would be nice to know what was the cause before putting it back on the processor. Thanks

Could there be a problem with the bar causing the chain to pull to one side , in turn having this affect on the rim ?

[gary112]

Maybe bar slightly bent

[billpierce]

Have good look at the bar and chain

[Matthew Storrs]

Bearings that the sprocket runs on? If bearings are going I’d guess it would have this effect

[lurkalot]

Looking at that photo, it looks almost like the chain has never run on the left hand rail of that sprocket.  Does it run inline properly, is the chain wide enough to span both sides of the sprocket?  I know nothing about processors, this is just an observation.

[Woodworks]

Been out checking the bar and the spacer the goes with it. The bar is as flat as a pancake and dressed square but the grooves on the bar and especially the spacer are a little flared where the chain comes on and off. Not sure which came first though.

 

lurkalot. yes, the chain would normally run smack bang in the middle of the drive sprocket.

 

Matt. Hard to tell as it goes straight onto a spline attached to a hydraulic motor. I can turn it and it feels normal. 

[Ratman]

You fit a new chain recently?

[Woodworks]

6 minutes ago, Ratman said:

You fit a new chain recently?

Change chains all the time

[Ratman]

Change chains all the time

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.