Canyon Angler
Addicted to ArboristSite
Airplane propellers break the sound barrier ... chainsaw chains, not so much. 
Chain Saw Math
- Thread starter Philbert
- Start date
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One thing I really like about Philbert's chain saw math is that he works with link dimensions and not geometric circle diameter, radius, and circumference. That seems to make it easy to convert the RPM to linear distance without using the constant, pi and other formulas. That being said, if you ever need to use the pi constant and don't have a scientific calculator handy, use the fraction, 355 / 113. It's 100,000 times more accurate than 22 / 7 and still rather easy to remember.
Where did I come up with that? Well, I used to program computers for a living back when no pi constant was built into the languages. I wrote a program to find the most accurate fraction that was better than 22 / 7 and discovered 355 / 113 was the best without getting too complicated.
Where did I come up with that? Well, I used to program computers for a living back when no pi constant was built into the languages. I wrote a program to find the most accurate fraction that was better than 22 / 7 and discovered 355 / 113 was the best without getting too complicated.
Saw Fixr
ArboristSite Operative
Philbert,
I didn’t check your math, but it looks reasonable. However I use the same 200rev/sec as an analogy, when I try to emphasize to a customer that there’s nothing “safe” about a ”safety” chain. Low/reduced kick back...maybe. Safe? Ahhh, No....
I didn’t check your math, but it looks reasonable. However I use the same 200rev/sec as an analogy, when I try to emphasize to a customer that there’s nothing “safe” about a ”safety” chain. Low/reduced kick back...maybe. Safe? Ahhh, No....
Same here: 'low kickback' or 'reduced kickback'. It will still cut your leg off as easily as a tree, and it won't feel bad about it.
Philbert
BUMP!
This came up in a conversation today. Still relevant.
Philbert
This came up in a conversation today. Still relevant.
Philbert
15 years have passed since post 1 was asking for someone to look over the data.
"3/8 pitch chain is not 0.375 chain, 1640 drive links per 100 feet.
A 20 inch called length loop to me means 72 drive links and 70 is some manufacturer bucking the trend. What is the most common dl count for 18"? In the 3/8lp it is generally 61 in Stihl and 62 in brand x. A full sized 3/8 bar is more I am confident; you still think 70 dl is 18"?
"3/8 pitch chain is not 0.375 chain, 1640 drive links per 100 feet.
A 20 inch called length loop to me means 72 drive links and 70 is some manufacturer bucking the trend. What is the most common dl count for 18"? In the 3/8lp it is generally 61 in Stihl and 62 in brand x. A full sized 3/8 bar is more I am confident; you still think 70 dl is 18"?
I rounded off numbers to keep the math simple for those following at home. Adjust as needed.
The actual length of the bar is irrelevant for the calculations . Only the number of teeth on the drive sprocket, the chain pitch, drive link count, and drive shaft rpms matter.
Philbert
