Husqvarna 357 rebuild

[Toad]

I was having a little think about chain speeds in relation to my initial question about going with a .325 or a 3/8 chain over the last few days and sat down last night to work them out. 

 

Basing the calculations on the quoted max power engine speed of 9600rpm

 

A .325 chain with a 7 tooth rim has a chain speed of 18.49m/s

A .325 chain with an 8 tooth rim has a chain speed of 21.13m/s

A 3/8 chain with a 7 tooth rim has a chain speed of 21.34m/s

A 3/8 chain with an 8 tooth rim has a chain speed of 24.38m/s

[peatff]

How does pitch affect chain speed ?

[Toad]

11 minutes ago, peatff said:

How does pitch affect chain speed?

It's the length between the drive links essentially. The chain speed should be distance between drive links x no. Of teeth x engine speed/60

[peatff]

8 hours ago, Toad said:

It's the length between the drive links essentially. The chain speed should be distance between drive links x no. Of teeth x engine speed/60

Thanks for that info.

[bmp01]

12 hours ago, Toad said:

I was having a little think about chain speeds in relation to my initial question about going with a .325 or a 3/8 chain over the last few days and sat down last night to work them out. 

 

Basing the calculations on the quoted max power engine speed of 9600rpm

 

A .325 chain with a 7 tooth rim has a chain speed of 18.49m/s

A .325 chain with an 8 tooth rim has a chain speed of 21.13m/s

A 3/8 chain with a 7 tooth rim has a chain speed of 21.34m/s

A 3/8 chain with an 8 tooth rim has a chain speed of 24.38m/s

Thanks for that eye opener, had blindly believed chain speed was function of engine speed and no. of teeth on sprocket. But now  you come to mention it .... 

[Toad]

23 minutes ago, bmp01 said:

Thanks for that eye opener, had blindly believed chain speed was function of engine speed and no. of teeth on sprocket. But now  you come to mention it .... 

 

I hadn't appreciated the difference between the chains. 

 

I know in the real world a saw with a .325 chain may well end up holding higher rpm in the cut than one with a 3/8 chain, but I thought it was really interesting when looking at 7 pin and 8 pin sprockets vs different chain pitches.

[Heavy Oil Saw]

It's the length between the drive links essentially. The chain speed should be distance between drive links x no. Of teeth x engine speed/60

Where did you get the 60 from? I ain’t much use at maths, so not questioning your method, just curious.

[Toad]

Just now, Heavy Oil Saw said:

Where did you get the 60 from? I ain’t much use at maths, so not questioning your method, just curious.

Engine speed given in RPM, chain speed in metres per second.

[Heavy Oil Saw]

@Toad Sorry, I meant in your original equation “distance between drive links x no. Of teeth x engine speed/60”. You’ve divided by 60 at the end of multiplying, where did the 60 come from?

[htb]

Changing from minutes in revs per minute to meters per second.