Comparing Chainsaws Mathematically

 Last fall, after everything flooded, there were tons of logs left all over the beach, the river banks, and even in the ponds.  I'd see men head over on their ATV's pulling trailers, head over, pull out their chainsaws, to cut the logs into usable pieces for heating during the winter.

Chainsaws are important up here in Alaska because so many houses use wood burning heat to supplement the oil heat and they use wood when they take a steam.

So I developed a math exercise so students can learn to compare power to weight ratios, find toque, and discover how fast the chain itself is going.  I had fun researching it as I don't usually use a chainsaw.

Formulas you will need.

1. Power to Weight ratio where you divide the Horse power number by the dry weight.  The Power  to weight ratio tells you how much power it has for each horsepower.

2. Torque is (Horse power x 5252)/RPM.  Torque is a way of talking about the work a machine does. 

3. Speed of motor turning is to take the RPM/60 gives you revolutions per second. 

Take the answer 

4. Speed of the chain.

Step 1.  Top RPM x number of teeth.

Step 2.  Take answer from step 1 x (.375 + 3.75)

Step 3.  Take the answer from step 2 x 60.

Step 4.  Take the answer from step 3 / 12

Step 5.  Take the answer from step 4 / 12 

Step 6.  The answer from step 5 is the speed of the chain in mph.

Place the answers in the following table

Chain saw	STIHL MS 271	Husquava 455 Rancheer.
Power to weight ratio
Torque
Speed of motor
Speed of chain

Compare and contrast the power to weight ratio, the torque, speed of motor, and speed of chain.

Please answer the following two questions.  Write in complete sentences.

1. Based on the answers, which chainsaw would you recommend?

2.  Based on personal experience, which one would you recommend?

I've shared this with you so if you want to try something like this during this time of distance learning, go a head.  I had two teachers tell me they were trying the outboard motor exercise I shared this past Friday.  They found it fun and enjoyed it.  Let me know what you think, I'd love to hear.  Have a great day.