Ironworker
Addicted to ArboristSite
Which gives more torque on a ported 70cc saw 7 or 8 pin.
7 or 8 pin
- Thread starter Ironworker
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DrewUth
Jack of all trades, master of none.
I would think it was like gearing down your motorcycle- smaller drive sprocket = more torque. Right?
Rx7man
Cattle Rubbing Post
it would be the 7 pin
You have no use for torque though, Piltz says chain speed is GOD.. use a 12 pin if you can get one
You have no use for torque though, Piltz says chain speed is GOD.. use a 12 pin if you can get one
Is this a trick question? The torque output at the sprocket is the same in foot pounds regardless of what sort of sprocket is installed. The tension achievable at the chain will be higher with the smaller sprocket.
Which sprocket makes the saw more likely to operate at a higher torque or a higher hp revolutions per minute is another way to look at the question in post 1.
Which sprocket makes the saw more likely to operate at a higher torque or a higher hp revolutions per minute is another way to look at the question in post 1.
Rx7man
Cattle Rubbing Post
Good point... I just take it to mean "will the 7 pin make the saw feel more torquey", which would be true.
PA Plumber
Addicted to ArboristSite
Ported? Don't know. Stock?
An 8 pin and long bar really get "doggy" in Eastern Hemlock. Seems like it wouldn't be a lot different on a ported saw.
An 8 pin and long bar really get "doggy" in Eastern Hemlock. Seems like it wouldn't be a lot different on a ported saw.
Rx7man
Cattle Rubbing Post
If you like leaning into it, the 7 pin will work well, 8 pin if the chain is sharp and you let the saw do the work.
A 7-pin sprocket will always have more torque than an 8-pin on any and all saws. It's a simple matter of gearing. Which one will cut faster depends on the saw. In the case of a 70cc saw, stick with 7-pin.
Rx7man
Cattle Rubbing Post
Wouldn't that depend a lot on the wood you're cutting? a 70cc saw cutting 12" stuff would certainly be faster with an 8 pin... go up to 30" wood and the 7 pin will probably be easier on the saw.
FrankyK is right though.. the saw always makes the same torque, but pull on the chain will change depending on the gearing
Torque output to the chain will vary by gearing. Imagine a 10-Speed bicycle. It's ALWAYS easier to pedal in first gear, no matter how strong the rider. How fast can the bike go in 10th gear depends on the rider and the grade of the surface.
Again, torque to the chain will always be greater with the 7-pin. Chain speed will vary depending on wood and power head.
Again, torque to the chain will always be greater with the 7-pin. Chain speed will vary depending on wood and power head.
Rx7man
Cattle Rubbing Post
I understand you, but the amount of torque *you* produce on the bicycle pedals doesn't change with the gearing.. the torque you get at the wheels does.
It's really a matter of splitting hairs and terminology.
It's really a matter of splitting hairs and terminology.
You're defining power, not torque. Power does not change. Torque does. Torque is a function of the length of the lever arm, ie the diameter of the sprocket.
http://mechanicalmania.blogspot.com/2011/07/how-does-gear-ratio-affect-torque.html?m=1
https://en.m.wikipedia.org/wiki/Torque
http://mechanicalmania.blogspot.com/2011/07/how-does-gear-ratio-affect-torque.html?m=1
https://en.m.wikipedia.org/wiki/Torque
jmssaws
Addicted to ArboristSite
I don't think there's a flywheel horse power on a saw its a to the tires type deal, only thing that matters is turning the chain. The tourqe at the crank won't change but it does at the chain. Your saw may run your chain with a 8 but need a 7 to run mine or vise versa, to many variables to say one is better than the other across the board.
Rx7man
Cattle Rubbing Post
Chain has linear motion, so it doesn't have any torque (torque is force around an axis).. it has a certain amount of pull.. the saw's engine makes torque, and a bigger or smaller sprocket doesn't change how much torque the engine can produce, but a smaller sprocket will increase the pull on the chain... I understand anyone who calls that torque, and say it myself, even though scientifically speaking.
It's inverse is a wrench on a bolt... you can only pull so hard, but you can increase the torque you apply to the bolt by using a cheater or longer wrench
It's inverse is a wrench on a bolt... you can only pull so hard, but you can increase the torque you apply to the bolt by using a cheater or longer wrench
Get some big wood , do some timed cuts with both keeping a good load on the saw with both and report back, most likely the 7 pin will cut faster unless your one that lets the saw scream way out of the peak HP RPM. Steve
Why are 8T sprockets even made if they are slower and supposedly harder on a saw ?
jmssaws
Addicted to ArboristSite
I have a couple saws that will run a 36" full comp very well with a 8 in hard wood but there not 70 cc and there's not much difference between a 7 or 8 on them. If your saw turns 10500 with a 8 in the wood maybe it will turn 11500 with a 7, wich one is faster?
cus_deluxe
Commie Satan turd
Whydo people port saws? Not necessary but cool and stuff. And seriously, think of it this way. An 8 tooth rim is physically bigger than a 7 pin, meaning bigger diameter. Which as brad said earlier is part of the definition if torque. Bigger diameter rim=bigger lever= Less mechanical advantage for crank vs smaller rim.
