Chain jumping off sprocket

[jack76]

I bought a husky288 and it came with a 20" bar. The bar had the same pitch and guage as the sprocket and my chain. When i went to cut the chain jumped the bar. I looked up the oregon number of the bar and found that the bar was for a eight toothed sprocket. The sprocket for the 288 was an 7 tooth. Could this have caused the chain to jump off? I have since bought the correct bar. I am milling with this saw on a logosol setup with a ripping chain and am new at it.
Hard telling not knowing why the chain jumped, ruined my first chain. Maybe sprocket is worn so I will invest in another??

 

[lone wolf]

I bought a husky288 and it came with a 20" bar. The bar had the same pitch and guage as the sprocket and my chain. When i went to cut the chain jumped the bar. I looked up the oregon number of the bar and found that the bar was for a eight toothed sprocket. The sprocket for the 288 was an 7 tooth. Could this have caused the chain to jump off? I have since bought the correct bar. I am milling with this saw on a logosol setup with a ripping chain and am new at it.
Hard telling not knowing why the chain jumped, ruined my first chain. Maybe sprocket is worn so I will invest in another??

Now and then they come off but not often. if it happens a lot something is out off true or wrong .Notice what causes this if you can was it loose when it happened?

 

[jack76]

jumping chain

chain was tight. I was only cutting for 30 seconds.
I will try my new setup tomorrow

 

[J.W Younger]

I doubt the smaller diameter of the drive rim caused it, maybe othe issues with it.
How about the fixture forcing the bar not straight?

 

[jack76]

I will check on that tomorrow..Thanks

 

[lone wolf]

The more I think about it if the chain came off that fast for no obvious reason maybe it was not on the sprocket to begin with.

 

[jack76]

Roger that

 

[jack76]

reply to lone wolf

Turned out the drum and sprocket were worn. I got another that was in better shape while I wait to buy a new one. I've been working on milling technique now. I also bought a new bar. The logosol timber jig takes some getting used to but each board comes out better.

 

[Philbert]

I . . . found that the bar was for a eight toothed sprocket. The sprocket for the 288 was an 7 tooth. Could this have caused the chain to jump off? I have since bought the correct bar.

As others noted, the number of sprocket teeth should not have made a difference if the sprocket is for the correct chain pitch. If Oregon referenced that particular bar for use with an 8 tooth sprocket, it probably had to do with specifying the correct number of chain drive links to use with that combination.

Philbert

 

[jack76]

chain drive links to sprocket

Thanks for the input...This site has great members