chain weight

[Fish]

Well, one could mount the bars on a car engine and go off in that direction, I guess.

But Carlton .050 ga. seems to be preferred by many of the
racing chain makers, definitely not .063 ga. in any brand.

 

[timberwolf]

If your not interested in suttle aspects of physics as it applies to a chain don't bother reading on!

I thought about aspects of the chain that are not covered by conservation of energy in movement.

Given that energy can not be created or destroyed, it can only be transformed from one state to another.

Two main areas come to mind.

1 direct transformations into heat due to friction - this would be evident in the friction between the bar and chain wich is dependant on the coeficient of friction and the forces pushing the chain against the bar. Another heat transformation is the friction generated in the flexing of the chain. the coeficient of friction and the tension forces within the chain play part in this. BOTH of these energy transformations due to friction and are directly proportinal to the mass of the chain being rotated.

2 indirect transformations into heat due to counteracting forces that load the engine and expel the heat energy into the power head. I can see two potential for this phenomina.

2.1 the first is related to the balance of mass above and below the rivet line of the chain. If there is more or less mass above the rivet line, as the chain link approches the tip section of the bar the section of the chain undergoes in increase in velocity, while the portion of the chain below the rivets is reduced in velosity. If for example ther is more or less mass above the rivets there would be an net increase or decrease in kinetic energy, this energy needs to come frome somewhere in the system. Note at the exit of the tip there would then be a counter surplus or deficet in energy, but the energy can not be transferd at 100% efficency due to the vectors that are created as the chain segments pass around the tip. The resultant vectors increase the force and ultimetly friction to the bar. Greater chain mass will excentuate this phenomina.

2.2 Changing rotational accelerations of individual chain links as they move around the bar. You need to look at each chain link from its center of mass located somewhere between the rivets. As the chain link moves along the flat of the bar it has no rotational energy. As the chain link reaches the start of the tip a rotational acceleration is imparted on the link. this occurs in a few 10,1000ths of a second. At the end of the bar tip this rotation must be returned to 0. This acceleration/ deceleration requires energy, some of this energy is transferd within the chain with losses to heat due to friction, but the better part of the energy must come from the engine. again this energy requirement is directly porportional to the weight of the chain. A more eliptical shaped bar with slower transitions between the flat and the drive/tip would reduce this factor, as does larger drive/tip sprockets.

I did some trial calculations and found that at 13500 rmp a 335 gram 20" chain was requiring about 500 watts or about 0.67 of a HP to overcome acceleration related losses. A 380 gram chain would require 600 watts or about .80 of a HP. This did not include friction losses that would also be directly related to chain weight..

Hey thats like having an extra 0.13HP


Timberwolf

 

[Crofter]

Wow

I felt these forces were actinhg here somehow but sure wouldn't have been able to describe it so. Think I can see why it has more effect on a racing situation since the chain speeds there are about double in the cut to what working saws might run. The fricional losses due to the difference in weight should go up as the square of the velocity so the losses would be 4 times as much if you double the chain speed. Good work.

Frank

 

[ricksvar]

Whatever gentlemen,

I do most of my cutting in the woods,not at the county fair.

Rick

 

[daveb]

WTF

 

[Crofter]

Daveb this is WTF its all about

I think its all part of the pool of knowledge here on this forum. Some things interest some people and not others.

Frank

Originally posted by timberwolf
Granted the mass of the chain likely only makes a small difference, so does a lot of other aspects like; polishing the ports, filing the gulets, thining the botom side of the top plated, using synthetic oil, filing back the tooth, replacing the choke plate with a primer, upgrading the air filter, various engine tweeks, ect ect ect........ 1% here 2% there. Many of the improvements are cumulative and even coumpouding to each other, and many are win-win with no apparent, relevent or unacceptable draw backs.

Building a winning race car is not just about building the best engine, it is considdering and maximizing all available potentials.
Don't forget many of the best consumer sports cars were developed for the race track. Speaking of race cars, why would they even considder using aluminum and magnesium wheels, drive lines and engine components if there was not an advantage in reducing rotational weight.


Sure it is only 10% more chain weight, but that make the diference between the power head of the saw moving 25 tons and 22.5 tons an hour.

Timberwolf

 

[Kneejerk Bombas]

This is one of the better threads I read here yet.

I wonder how many of the benifits of light chain weight is weight, and how much is reducing friction, as well as clearing a path for chips.

 

[Crofter]

Mike I think your suggestions that the smaller dimensions of the lighter chain that result in less friction and better chip clearance, could well have a greater affect on cutting speed than the effet of less weight in itself. I think most of the discussion was whether weight made ANY difference. Timberwolf came up with something like a tenth of a horsepower difference at an engine speed of 13,00 rpm in the cut. It would take a stop watch to tell the difference. You wont notice it up the tree. Its knowing and taking advantage of every one of the little details that makes a difference when someone elevates something like a chainsaw to the level of an art form. A lot of people would think us clean crazy!

Frank

 

[Crofter]

Chain weight for competition

The topic came up last weekend at Gypo's about chamfereng tie straps to shave weight but Ehp says he doesn't because in lots of competions now, altering the chain chassis is not allowed. Carlton seems to have a weight advantage over Oregon as Timberwolf noted at the start of this thread. Carleton is also what Art Martin favoured but I don't know if it was strictly from the weight angle. Oregon is slightly faster, new out of the box but when modified a bit this advantage is gone. What is being used the most on the competition circuit?

Frank

 

[ehp]

out in the east most chains are oregon, carlton is not used much here and most stores donot carry it.