Yup.
Double the speed is four times the energy.
Ms660 with 6 k products 11 pin rim sprocket today
- Thread starter Spanky
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Double the speed is four times the energy.
I made a miscalculation recently on a thread calculating speed with a particular saw at power speed rpm.
I will have to correct. It should have been double of what I said. 120kph (76 mph) 7T 3/8
First off...
What I read from Carlton years ago was:
Chain pitch is the measurement from between three rivots then divided by 2.
Assuming that's true then the only way you could come up with pitch measurements would be to do just that.
This would mean one span is longer and the next span is shorter. (Looks like it)
Driver centre to driver centre would be exactly pitch x 2
One long span and half of a sort span on each end = one long span one short span (3rivots)
Your example is:
3/8 x 2 = 6/8 = .750" x 11 = 8.250" travel per revolution
OR
.375 x 22
--------------------------------------------------------
Revolution = 8.250" travel x RPM
Divided by 12 for FPM
5280 ft per mile
Your saw exceeded 2 miles a minute with over 10600 FPM.
X 60 for MPH = over 120MPH.
That crazy
My WCB approved bucking pants are only 3600 FPM
I/3 protection
Do you think they will stop it?
I'm going to try. I got nothing else to do....haha.
Spanky
ArboristSite Operative
That's why I think the formula just taking in the number of pins and not diameter is off a little
I'm not sure what part of square peg in round hole don't they understand.
Haha.
You mean you think finding the circumference is wrong?
All though the chain gives the appearance of contouring the circle, perhaps the ends float.
I'll work a 3/8 7T out both ways and see.
It has a 35 mm OD x PI /3.1415
Circumference = 109.9525
Haha.
You mean you think finding the circumference is wrong?
All though the chain gives the appearance of contouring the circle, perhaps the ends float.
I'll work a 3/8 7T out both ways and see.
It has a 35 mm OD x PI /3.1415
Circumference = 109.9525
109.9525 × 10,000RPM ÷ 1000mm = 1099.525m/min
109.952m per 1000 rpm
1KM, 99.525m
OR
1099.525m ÷3.37FT = 3705.39925 FPM
--------------------------------------------------------
.750 × 7 = 5.250" of chain per revolution
5.250" × 10000 RPM, ÷ 12 =
4375 FPM
670 FPM difference?
About 15% error on a small sprocket.
I tried to do it with getting the Dia of sprockets on line and matching what Husqvarna posted for specs but I couldn't get their numbers that way.
109.952m per 1000 rpm
1KM, 99.525m
OR
1099.525m ÷3.37FT = 3705.39925 FPM
--------------------------------------------------------
.750 × 7 = 5.250" of chain per revolution
5.250" × 10000 RPM, ÷ 12 =
4375 FPM
670 FPM difference?
About 15% error on a small sprocket.
I tried to do it with getting the Dia of sprockets on line and matching what Husqvarna posted for specs but I couldn't get their numbers that way.
Spanky
ArboristSite Operative
I just measureed my bar at 2.510 sprocket at 2.32 so it would be less than engine rpm but I need to do the math also by diameter as a belt and see what I get for fpm.
Spanky
ArboristSite Operative
12015 fpm at 13000 engine room usin heg sheeve diameter formulas . I'm sure the chains drag has some loss withers it's 151fpm I don't know but that math seams to fit my mechanical logical ability of comprehension .190 difference in diameter x13000 =10530fpm
D x π = C
2.3 × 3.1415 = 7.22545" circumference
7.22545" x 13000 RPM
= 93,930.85"
Divided By 12^^↑^^ for FPM
=7827.5708333 FPM At 1300 FPM
*I just noticed I did the Dia at 2.3 not 2.32
Your numbers are way off. Something went wrong.
Again, you can not measure from the circumference of a circle X revolutions.
On paper I gave the margin of error on last post with 3/8 7T in reality the margin would be much less due to different positions of the chain on the sprocket per revolution. However, driver center to centre distance X sprocket slots can not lie.
Not sure what the deal was about in regards to matching up the sprocket size to the tip size and measuring tip sprocket FPM differences? That was 'a little geeky'..even by my standards... Lol
2.3 × 3.1415 = 7.22545" circumference
7.22545" x 13000 RPM
= 93,930.85"
Divided By 12^^↑^^ for FPM
=7827.5708333 FPM At 1300 FPM
*I just noticed I did the Dia at 2.3 not 2.32
Your numbers are way off. Something went wrong.
Again, you can not measure from the circumference of a circle X revolutions.
On paper I gave the margin of error on last post with 3/8 7T in reality the margin would be much less due to different positions of the chain on the sprocket per revolution. However, driver center to centre distance X sprocket slots can not lie.
Not sure what the deal was about in regards to matching up the sprocket size to the tip size and measuring tip sprocket FPM differences? That was 'a little geeky'..even by my standards... Lol
Spanky
ArboristSite Operative
As posted before when working with belts and pulley the diameter of the drive pulley size in relationship to the driven pulley effect speed .of the driven The same can be said on a dirt bike with sprockets . The actual strobe fpm is 10640 fpm of the chain and the actual engine rpm is not 15000 it's less so the formula using just sprocket pins is wrong .Anyone with simple mechanical ability can figure that the rpm or fpm which is the same when the driven sprocket is same size as driver is going to be equall to engine rpm . The driver is .190 smaller than the driven . By taking .190 x 13000 engine rpm it's closer to the actual measured for than the pin formula . This is why we call our chainsaws kissin piston saws for the kiss method keep it simple stupid Everytime we try some fancy formulas they typically don't add up to actual test measured with appropriate testing equipment .
^^^ no ****..its a bullet proof system
Madsen's info screen shot.
I think we're being trolled here.
Canyon Angler
Addicted to ArboristSite
Lmao..OK I'll play
Pertaining to a saw ONLY here. You will get a different behavior with increased/decreased sizes within the tip area but you have not mention of this, only stating the obvious and that being: saw drive sprockets run at a different ratio than the tip sprocket. Heeello!
IF the measurement is correct from driver centers then how possibly could it be wrong. I can see error with using diameter to circumference as on paper if you drew 14 proportionate lines representing the base of the chassis around the circle and the circle representing the 7T sprocket then there is possibly 15% error. In a real application the error would likely be mainly arounding the back of the sprocket. Possibly 6% error.
Btw, the latter would give an extremely high rev to match your FPM count.
Show your work how you come up with over 10600+ at 13,000.
I'm interested.
I just thought that was common sense?
Who gives a flying phuck!
try the right formula next time.
the inertia must be incredible? 2" from the axis and all. Must need extra balancing too.
MG porting
ArboristSite Guru
That's a lot lot lot of rpm for a 660 not sure if I would ever run one that high. I'm sure it would make a great cookie cutting saw.
MG porting
ArboristSite Guru
If this is going to be a saw for competition I'd say OK but in real world use for logging or even bucking fire wood no thanks 7pin or 8pin are the best way to go a 11pin is just nuts.
MG porting
ArboristSite Guru
If you can time your cuts with the 11pin in some hard wood then put a 8pin on and do the same thing I bet you'll find that the 8pin will do better than the 11pin.just saying. 
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