chain weight

[timberwolf]

I would like to bring the topic of chain weight and it's effects on performance up for disscussion. Sorry if this is a bit long.

I received a couple of loops of full chisel carleton chain as an early Christmas present from my dad, right away I noticed that it was lighter than the Stihl RS chain I have been. The tie staps were visually thinner on the Carleton chain, so I weighed the two chains.

Note both Stihl and Carelton chains were sharpend for ripping so they would have about an equal ammount of metal removed.

Stihl 3/8 full chisle 20" = 380 grams or 13.5 oz
Carelton 3/8 full chisle 20" = 335 grams or 11.9 oz

Wow 10% difference
On a 32" chain it's nearly 100 grams or about 3.5 oz difference, though I was compairing full comp to semi skip for the 32".

I tried to look at it from a mathmatical formula to determine how much energy is used in accelerating the extra weight around the tip of the bar and the drive sprocket, but the calculations got rather convaluted and would require other data like coefficient of friction (chain to bar) to get a quantative awnser. No matter how I approched the formula the mass of the chain always formed a direct relationship to the forces required or generated.

So my guess would be: That what ever the losses were asotiated with a given chain would be increased proportionatly with increased chain weight.
ie. 10% increased weight would increase related power losses by 10%, also 10% increase of forces exeted on centripitally related wear point of the bar and crank bearing.

Other interesting numbers I found while trying to support this hypothisis with calculatons. (based on 13500 rpm 8 tooth sprocket 3/8 chain)

Each drive link passing arround the bar places about 20 lb of outwar force at the tip, a 30 lb at the sprocket.
about 1400 teeth pass over the tip of the bar every second
about 15 lb of chain is slung around the tip of the bar every second. That is 85000 teeth weighing 900 lb a minute or 5.1 million teeth weighing about 25 tons an hour.


Anyone have Ideas on the real world impact of chain weight, or approches that could be used to calculate the therotical values.


This is likely theroretical and not a practical point, but it should be an interesting discussion.

Timberwolf

 

[Fish]

Time for everyone to put their hip boots on!

If you go back and look at the pics of Art Martin's racing chain,
I think that weight is a big factor, but I am no expert on the
matter.

 

[timberwolf]

Looking at the matter technically I think weight is significant, I wonder if it even is a hidden factor in why chains perform better with metal removed from the gullets and teeth that have been filed back to the witness marks. (the chain is made lighter in addition to other factors).

Timberwolf

 

[Crofter]

It takes energy to accelerate mass or change its direction. This is exactly what happens constantly at EACH end of the bar and any added weight will cause an additional friction loss into the bar. Are you sure though you havn't got a decimal point in the wrong place? I didn't realize it amounted to that many foot pounds per hour. I thought the racing fellows just wanted to save postage when they mailed those fancy racing chains around the country!

Frank

 

[fun_chopper]

just an un proven thought..wouldnt the inertia of the chain of greater weight as it is propelled outward be the same as the inertia of the chain traveling inward, be the same as the inertia of a lighter chain, given that the firction on the bar remains a constant, and the chain recieves the same amount of aerodynamic drag? I would think that chain weight in relationship to inertia, drag, and friction would be the same no matter the weight. The only difference I see is lighter chain will accelerate faster than heaver chain, because of the force required to send that chain into motion, but once propelled to a given speed, that object would remain at a given speed, no matter the weight. A heaver chain would remain closer to the baseline speed under a load, because the weight of the chain would help keep it at a given speed, due to the effects of inertia. So by establishing this in my own mind like this, all chains based on inertia, drag, acceleration, and friction seem to be created equal!-Have fun with this theory!!-Matt

 

[timberwolf]

Yes it does take energy to change the velosity or direction of an object, but it gets complicated with a chain. As I am understanding it, the chain is in some ways like a spinning object, because a significant amount of energy is transfered along the length of the chain the laws of conservation of energy come into play. as one part of the chain is accelerating (requiring energy input) another is decelerating and giving energy up to the system, much of the energy is transfered through the chain from high to low energy potentials.

And there is the centripital force also that wants to spin the chain into a circular shape rather than the elongated conture of the bar, this also puts load on the sprocket and tip. Hence any weight reduction would reduce friction, chain tension, and wear.


I think this gets complicated once you start to look at all the dynamics involved.

TW

 

[Crofter]

If the chain were rotating in a perfect circle like a flywheel it would take no additional energy to keep it going but with the configuration on a saw it has to be pulled from the straight run across the bar and be forced into the turn around the sprocket ,then straightened out again and headed back into the straight run across the bar in the opposite direction only to be repeated at the other end of the bar. The more energy the drive sprocket has to put into the chain, the harder it has to pull it against the bar, since the bar has at least a slight arc to it and doesn't come onto the drive sprocket in a tangent.

Frank

 

[fun_chopper]

Energy is lost, there is no dispute however, velocity keeps the chain moving despite the shape of the bar, and the engine keeps the chain at a constant speed. The weight of the chain forces it forward on top, and aft on the bottom even after power inputs have ben removed. I would think that friction, and weight of a chain have very little to do with each other in this senerio, because the friction and weight are all constant. Friction is relative to weight. Inertia is not relative to weight, therefore a heavier chain has more inertia than a lighter chain. Thats where the difference is to me..With all of these variables, you are talking about such variations that a user wouldnt notice.

 

[tony marks]

more wt takes more to attain speed,
but also seems it would take more resistance to slow it dn.perhaps equealing the two .if u was gonna hit a deere would u rather hit it with a dump truck or a ford escort. man, i done turned this into rocket science aint i.

 

[Crofter]

Fun Chopper

I had a theory once that if I put my fathers big satety toed miners rubbers on and overcome their inertia got them up to speed their weight would be no handicap and their momentum would allow me to beat my brother in a short foot race. The Problem that I hadnt forseen was at the end of the race when I had to bush her to get stopped !

Frank

 

[Crofter]

Carlton Chain Lighter

TW

are the drive links .50 gua. througout their lengt or are they just reduced to .50 on the drive tang as in the Oregon. does most of the difference seem to be in the width and thickness of the tie straps or is it a little bit everywhere?. It would probably be difficult to time the difference in spoolup time of the different weight chains on the 066 but I bet if you put that 32 inch bar on the 026 you could time the difference with the different chains . Hard to judge how much difference in cutting performance is caused by the weight and how much is different shapes angles etc. between Oregon and Carlton

Frank

 

[Gypo Logger]

I think the weight of a chain is inconsequential in all cutting applications except racing, although the relative weight of a chain may have something to do with the gauge or how well it was made. Cutting speed can best be attained by a strong motor, sharp chain and raker height and sprocket size that match.
John

 

[dbabcock]

I agree with John on this one. Mass and acceleration are linked at the hip. If you're not worried about how fast you can get the chain from 0 to whatever speed (as in a dead start race), then the weight of the chain really doesn't get into things unless perhaps the greater inertia a heavier chain carries at a constant speed. I would think that the inertia thing is probably a small part of a lot of other things going on as well, however.

 

[Crofter]

Aw Doug I think you just want to agree with Gypo. Sur we are talking about something that is probably more than a little hypothetical, and as Gypo says probably only noticeable in racing. You wont notice it on your Pullon. However the ongoing parasitic energy loss in a constantly directional changing assembly is not the same thing as a constant rpm fixed shape like a solid flywheel.

Xander where are you?

Frank

 

[Fish]

I agree that the common user would not notice much difference
on cutting times, but on hotsaw contests, weight would be
a major factor on times.
I first started this fight long ago over the difference in gauge vs.
performance, and I purported that gauge would have no
performance difference in normal use, then Walt jumped in.....
In normal use, is one thing... In racing is another....
This thread is just starting....

 

[timberwolf]

Might be in left field here, but I don't think that chain inertia is very significant in terms of keeping the chain speed constant or to prevent bogging, here is why

the inertia is far greater from of all other parts that are rotating at 12000 rpm (the crank, clutch, sprockets, piston, conecting rod, fly wheel....) Noted: Piston only provides momentary inertia during stroke.

If inertia added performance, they would not be trimming fly wheel weights to bare minimum, and maybe thay would even add tiny lead weights to the chains, or better yet even tungsten.
Is this is why carbide chains are better? LOL

Take a 5 lb brick and tie it to a rope, them swing it above your head in a circle til your tired, then take a 10 lb brick and do the same thing, your tired much quicker as more effort is exerted.

TW

 

[dbabcock]

Yeah, you're right Crofter, I just wanted to patronize Gypo, my mentor. Yes, I agree that the radial acceleration of the chain will be a nonzero quantity due to differing radiuses, but I still suspect that it's effect on different mass chains would be a rather weak second order one.

 

[Newfie]

But both of those bricks are gonna hit ya in the head.

 

[Crofter]

Sure, like I suggested earlier, Art Martin only removes mass from his chains to save postage not horsepower! And I am just stirring the pot, Timberwolf started this mess just to see if he could get you squabbling,

Frank

 

[Tony Snyder]

I suspect the flywheel has much more affect than the chain. Rotational inertia once set in motion would be use full, but with all the friction and two turnarounds; I wouldn't think the chain inertia would add or detract significantly. But, the racers ought to already know the answere from experiences.

Where are KD and Dennis on this?