Rudolf73
Addicted to ArboristSite
I know there have been a lot of discussions/arguments on AS about running 3/8 instead of .325 chain on 50cc saws and the arguement has not been settled as far as I know. Lately I have been designing chain elevators at work which look pretty similar to chainsaw bars (with teeth etc.) and run 3" pitch chain. (Unfortunately I can't include any pics due to patent issues) So as a result I have been doing a lot of chain size and speed calculations. This got me thinking about .325 and 3/8 chain speeds and how they compare.
I did some calculations and without getting to technical here is what I have found...
- The calculations were done at 10000rpm to simplify things.
With a .325 7 pin sprocket at 10000rpm - Chain speed is 19.4m/s or 63.6f/s
With a 3/8 7 pin sprocket at 10000rpm - Chain speed is 22.4m/s or 73.5f/s
So then I converted these numbers to include the number of cutters per metre or foot and got the following results.
.325 - Number of cutters passing any given point in 1 second @ 10000rpm is 587.4
3/8 - Number of cutters passing any given point in 1 second @ 10000rpm is 588
So the actual difference in cutters passing a single point per second is 0.1% (Not a real big difference right?)
It turns out that 3/8 chain runs around 15% faster than .325, but .325 chain has about 15% more cutters per unit length than 3/8.
Now just to clarify - these numbers are all based on my calculations and I may have missed something when converting between imperial and metric and back again. It would be good if other members could check my numbers just to make sure, Thanks.
I did some calculations and without getting to technical here is what I have found...
- The calculations were done at 10000rpm to simplify things.
With a .325 7 pin sprocket at 10000rpm - Chain speed is 19.4m/s or 63.6f/s
With a 3/8 7 pin sprocket at 10000rpm - Chain speed is 22.4m/s or 73.5f/s
So then I converted these numbers to include the number of cutters per metre or foot and got the following results.
.325 - Number of cutters passing any given point in 1 second @ 10000rpm is 587.4
3/8 - Number of cutters passing any given point in 1 second @ 10000rpm is 588
So the actual difference in cutters passing a single point per second is 0.1% (Not a real big difference right?)
It turns out that 3/8 chain runs around 15% faster than .325, but .325 chain has about 15% more cutters per unit length than 3/8.
Now just to clarify - these numbers are all based on my calculations and I may have missed something when converting between imperial and metric and back again. It would be good if other members could check my numbers just to make sure, Thanks.