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Re: Chainsaw Tooth Velocity
[Re: MolaKule]
#4707864
03/26/18 07:13 PM

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cpayne5

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(2*pi*1.5)x(4300/60)
first part is circumference second is revolutions per second
full revolutions x circumference = inches traveled per second divide by 12 to get feet
Last edited by cpayne5; 03/26/18 07:14 PM.



Re: Chainsaw Tooth Velocity
[Re: jhellwig]
#4707868
03/26/18 07:15 PM

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Linctex

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Edit 3 I didn't do it right at all. 3377 ft per second.
3,300 feet per second is way faster than the speed of sound that's high velocity rifle bullet speed
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Re: Chainsaw Tooth Velocity
[Re: A_Harman]
#4707871
03/26/18 07:16 PM

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MolaKule
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What's the trick here? Are you going to nitpick about how tall the teeth are, which would change the tangential velocity. How long is the bar? What is the radius of the drive sprocket?
Am I biting on your hook? No trick just simple calcs and units conversions to get to: How far will anyone tooth travel in one second? Sprocket radius was given as R = 1.5" and I stated that the tooth velocity (for all practical purposes) is approximately equal to the tangential velocity of the sprocket. Bar length is immaterial. The linear velocity of the chain, which carries the teeth and links, is the key.
Last edited by MolaKule; 03/26/18 07:19 PM.
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Re: Chainsaw Tooth Velocity
[Re: MolaKule]
#4707879
03/26/18 07:24 PM

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MolaKule
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A_Harmon and JimPghPA showed the correct calculations so we're going to give each a set of virtual BITOG Piston Cup Cufflinks. Mr cpayne5 will receive a virtual BITOG coffee stirrer.
Last edited by MolaKule; 03/26/18 07:27 PM.
Charlie Eppes: "Larry, have a minute?" Dr. Larry Fleinhardt: "Yes. Because we all have exactly the same number of minutes at all times, do we not?" From NUMB3RS



Re: Chainsaw Tooth Velocity
[Re: MolaKule]
#4707919
03/26/18 08:06 PM

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Donald

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The teeth will travel far enough in one second to rip your skin apart big time.
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Re: Chainsaw Tooth Velocity
[Re: Linctex]
#4707937
03/26/18 08:26 PM

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jhellwig

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Edit 3 I didn't do it right at all. 3377 ft per second.
3,300 feet per second is way faster than the speed of sound that's high velocity rifle bullet speed Eh. I forgot to devide by 60. The first time for some dumb reason I calculated 1.5 like it was a quarter of the circumference.
Last edited by jhellwig; 03/26/18 08:28 PM.
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Re: Chainsaw Tooth Velocity
[Re: MolaKule]
#4707958
03/26/18 08:53 PM

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CR94

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Why such an easy question? A more accurate answer would require knowing the chain pitch (per link) and the number of teeth on the sprocket. Or you'd have to define sprocket effective radius in a particular way.
2011 Toyota Prius now at 109K 1981 Mazda GLC (323) retired at 606K 1972 Subaru DL retired at 190K 1954 Chevrolet retired at 121K



Re: Chainsaw Tooth Velocity
[Re: Donald]
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03/27/18 07:29 AM

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MolaKule
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The teeth will travel far enough in one second to rip your skin apart big time. This sprocket speed was my old Homelight Chainsaw's speed. Some chainsaws have a rotational sprocket velocity of 7000 rpm.
Charlie Eppes: "Larry, have a minute?" Dr. Larry Fleinhardt: "Yes. Because we all have exactly the same number of minutes at all times, do we not?" From NUMB3RS



Re: Chainsaw Tooth Velocity
[Re: CR94]
#4708251
03/27/18 07:34 AM

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MolaKule
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Why such an easy question? A more accurate answer would require knowing the chain pitch (per link) and the number of teeth on the sprocket. Or you'd have to define sprocket effective radius in a particular way. Apparently it wasn't that easy for everyone. Not sure I understand your comment. The sprocket rotates such that its Tangential Velocity is the equal to the chain's linear velocity, which is the same velocity for any tooth or link in the chain no matter where on the bar that tooth or link might be.
Charlie Eppes: "Larry, have a minute?" Dr. Larry Fleinhardt: "Yes. Because we all have exactly the same number of minutes at all times, do we not?" From NUMB3RS



Re: Chainsaw Tooth Velocity
[Re: JimPghPA]
#4708253
03/27/18 07:37 AM

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MolaKule
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4300 RPM/60 seconds per minute = 71.66 revolutions per second.
The circumference of a circle = pi X Diameter or pi X 2 X Radius
Circumference of a 3 inch diameter circle is 3 X 3.14 = 9.42 inches
71.66 revolutions X 9.42 inches circumference = 675.0372 inches per second.
Divide by 12 to get feet per second.
675.0372/12 = 56.2531 feet per second and 4300 rev/min x 2*pi radians/rev x 1 min/60 sec x 1.5 in x 1 ft/12 in = 56.28 ft/sec, or about 38 mph. Quite a few responders had done the calculations properly but for some reason I could not get a simple answer to: How many feet will any one tooth travel in 1 second?If the chain's linear velocity is 56.25 ft/sec then the distance a tooth will travel in one second is; 56.25 ft/sec X 1 sec = 56.25 feet.
Last edited by MolaKule; 03/27/18 07:48 AM.
Charlie Eppes: "Larry, have a minute?" Dr. Larry Fleinhardt: "Yes. Because we all have exactly the same number of minutes at all times, do we not?" From NUMB3RS



Re: Chainsaw Tooth Velocity
[Re: MolaKule]
#4708276
03/27/18 08:10 AM

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MolaKule
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Another way of approaching the problem is:
Data: Sprocket RPM is 4300, Sprocket Radius is 1.5".
Anything touching the outer portion of the sprocket will by necessity have to attain a velocity equal to the Tangential Velocity of the sprocket.
The chain effectively "translates" the rotational motion to Linear Motion.
Vt = w*R, where Omega w is in radians/sec, R is in inches.
There are 9.55 RPM/Radian. (One radian is 57.3 degrees of rotation of a full circle, or 0.1592 of a circle).
1/0.1592 = 6.28; 6.28 is 2*Pi.
w = 4300 RPM / (9.55 RPM/Radian) = 450.3 Radians/sec.
Vt = w*R = (450.3 Radians/sec) * 1.5" = 675.5 Inches/Sec.
(675.5 Inches/sec) / 12 inches per foot = 56.28 Feet/Sec.
56.28 Feet/sec. X 1 sec. = 56.28 feet.
Last edited by MolaKule; 03/27/18 08:25 AM.
Charlie Eppes: "Larry, have a minute?" Dr. Larry Fleinhardt: "Yes. Because we all have exactly the same number of minutes at all times, do we not?" From NUMB3RS



Re: Chainsaw Tooth Velocity
[Re: MolaKule]
#5208441
09/09/19 10:50 AM

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jakewells

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How many pins are on the rim? That would determine the speed of the chain instead of just noting the size of the rim it comes in either 6, 7, 8, 9, 10, pin.
Also i prefer using a non tacky oil in any chainsaw.
2001 Mercury Cougar base 2.5l CD4E automatic.



Re: Chainsaw Tooth Velocity
[Re: jakewells]
#5208689
09/09/19 05:42 PM

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MolaKule
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How many pins are on the rim? That would determine the speed of the chain instead of just noting the size of the rim it comes in either 6, 7, 8, 9, 10, pin.
Also i prefer using a non tacky oil in any chainsaw.
It doesn't matter, as the linear velocity of the chain is a function of the Tangential Velocity of the sprocket. Put a red paint dot on any one tooth and find out how far it will travel in one second. If any one tooth is moving at a linear velocity of 56.28 Feet/sec. then in 1 second it will travel. = 56.28 feet. Data: Sprocket RPM is 4300, Sprocket Radius is 1.5".
Anything touching the outer portion of the sprocket will by necessity have to attain a velocity equal to the Tangential Velocity of the sprocket.
The chain effectively "translates" the rotational motion to Linear Motion.
Vt = w*R, where Omega w is in radians/sec, R is in inches.
There are 9.55 RPM/Radian. (One radian is 57.3 degrees of rotation of a full circle, or 0.1592 of a circle).
1/0.1592 = 6.28; 6.28 is 2*Pi.
w = 4300 RPM / (9.55 RPM/Radian) = 450.3 Radians/sec.
Vt = w*R = (450.3 Radians/sec) * 1.5" = 675.5 Inches/Sec.
(675.5 Inches/sec) / 12 inches per foot = 56.28 Feet/Sec.
56.28 Feet/sec. X 1 sec. = 56.28 feet.
Last edited by MolaKule; 09/09/19 05:44 PM.
Charlie Eppes: "Larry, have a minute?" Dr. Larry Fleinhardt: "Yes. Because we all have exactly the same number of minutes at all times, do we not?" From NUMB3RS



Re: Chainsaw Tooth Velocity
[Re: MolaKule]
#5208845
09/09/19 09:27 PM

Joined: Mar 2016
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CR94

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[quote=jakewells]How many pins are on the rim? That would determine the speed of the chain instead of just noting the size of the rim it comes in either 6, 7, 8, 9, 10, pin. It doesn't matter, as the linear velocity of the chain is a function of the Tangential Velocity of the sprocket. ... It does matter, because the most relevant tangential velocity (that equals the chain speed) is that at the effective pitch radius of the sprocket, not at its overall outer radius. Small difference, perhaps, but significant.
2011 Toyota Prius now at 109K 1981 Mazda GLC (323) retired at 606K 1972 Subaru DL retired at 190K 1954 Chevrolet retired at 121K



Re: Chainsaw Tooth Velocity
[Re: MolaKule]
#5209419
09/10/19 03:54 PM

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MolaKule
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I think the difference is going to be very small: For a sprocket (from the rim toward the center of the bore) you have an Outside (or Outer) Diameter, a Pitch Diameter, and a Bottom Diameter. See Page 3 of: Martin Sprocket EngineeringYou made me open up my old HomeLite Timberman ChainSaw but hey, it needed cleaning anyway. I put the sprocket measurements and calculations into MatLab and here are the Results: Here are the measurements of the ChainSaw drive sprocket: OD = 1.25" BD = 0.75" PD = 1.125" Sprocket RPM = 9000 Linear Velocity using OD = 1.25" Sprocket RPM = 9000 49.1 ft./sec = 49.1 feet linear travel in 1 second; Linear Velocity using PD = 1.125" Sprocket RPM = 9000 44.2 ft./ sec. = 44.2 feet linear travel in 1 sec. A difference of 10%. You still need those safety Chaps and HD Gloves! BTW, I need to sharpen the chain on this puppy as well.
Last edited by MolaKule; 09/11/19 10:00 AM.
Charlie Eppes: "Larry, have a minute?" Dr. Larry Fleinhardt: "Yes. Because we all have exactly the same number of minutes at all times, do we not?" From NUMB3RS



