Bucking Question

[Cold Logging]

. . The easiest way when Pre commercial tree thinning to put the top of the tree where you want it is to put the butt of the tree the opposite direction off the stump. Need lots of torque and speed to do it with a saw like a 242 Husky in 3-8" trees. . And a real sharp chain. Using the top of the bar gets them off the stump faster than the bottom of the
bar. . But I agree that part of it is that the weight of the saw aids in it. . I do think a saw looses some torque going over the nose of the bar. . Where's Stig or Holmen, they may know.

 

[CurSedVoyce]

I also think with back bar cutting, you are removing the chips from the kerf better, less build up to slow the chain.

 

[stig]

I've no idea, really.
I backchain as much as I can when limbing hardwoods, because with the bar lengths I run, I can point the saw almost straight down and it'll basically be weightless.
Makes a difference on the old back at the end of the day.

 

[murphy4trees]

Well maybe that's it.. its the weight of the saw adding to force applied on the chain..

 

[cory]

Could be, but back chaining seems better even when finishing cuts when you start in the kerf underneath the uncut wood and have to pull up on the saw

 

[Burnham]

I know that I don't know . I back chain when it is more useful, and don't when it isn't.

I define more useful from a largely ergonomic perspective, I think...though some bucking techniques (required by the situation) require it even when it's tougher on the body to perform.

 

[Marc-Antoine]

Aside of all that, I see a point in favor of the "it seems" :
When you are bucking on the ground, you automatically slows down to avoid going throw and burying the chain in the dirt.
But when you finish the cut upward with the log up side down, there is nothing to worry. So you cut with no hesitation, even if it isn't at full speed.

It isn't the case for the cooky cutters during their down-up-down cut though.

 

[Cold Logging]

When I'm actually cutting for Max scale per hour I don't get off the tree to do most of the bucking. I use the top of the bar a lot. . Ya gotta know what your doin and I don't clean the cuts off. But rather leave a little post at the heart that will break as soon as the.log moves. I will do that on root cuts plenty also. A friend of mine. Steve Crooks got killed by a root wad on a strip right above where I had cut. . If it'll drop and could get me I'll cripple the snot out of it and if I can drop the first log by morning usually the butt has dropped. Don't know how I got off on that tangent.

 

[Cold Logging]

Oh ya. When just bucking the full length of the bar with the top of the bar. I have noticed it isn't much faster. But it sure works the crap out of ya. . Holding 34" of bar into solid wood all day will cause ya to sleep real sound at night. Once you are in shape for it. Till then you need lots of ibuprofen.

It seems the top cuts faster than the bottom of the bar as long as the tip is exposed so the chips clear easily.

 

[sierratree]

The chain is actually running faster and more true, "out of the gate" with a pushing chain, than with a pulling chain. IMHO.

 

[stig]

You can't have one end of the chain running faster than the other. Not for very long, anyway.

 

[Marc-Antoine]

Actually, a saw chain is always pulled throw the kerf, either with the bottom or the top of the bar.
Really pushing the chain wouldn't work at all in a matter of cutting, it's like wanting to push a rope.

 

[gf beranek]

Whether cutting with the top of the bar, or bottom, the force delivered on the saw is either push or pull. The relativity of which has a very strong bearing on how we operate a chainsaw.

I've thrown far more chain while backchaining. Particularly with a loose chain. I have my own ideas on why this is so, but can anybody else here explain it?

It's not rocket science. I'm just curious to see how clear other sawyers in this forum understand the phenomena.

 

[MasterBlaster]

I toss em sometimes when I backchain, but it's usually because of the way the wood left the cut. I love backchaining - it keeps the crap off of me, which comes in handy when ants are involved!

 

[cory]

As far as throwing a loose chain, I would say it is because with backchaining, the sprocket is pushing the chain which causes a "bunching" force on the chain links, which would be particularly pronounced with a loose chain cuz there's no chain tension to prevent bunching, so any momentary misalignment between bar and chain could cause the loose, bunched up chain to be pushed out of the bar groove and thrown.

 

[MasterBlaster]

;>)

 

[woodworkingboy]

With hand saws you can get away with finer kerf saws that cut on the pull stroke, than ones that cut when pushing, for the reason that Cory explained. Not really bunched up with a hand saw, but the greater tendency to bend out of shape.and bind in the cut when pushing.

 

[squisher]

When cutting with the top of the bar if it isn't running/cutting straight or gets out of the groove slightly it flings off the tip. When cutting with the bottom of the bar if the same happens the lower guide helps it come onto the sprocket.

 

[HolmenTree]

I'll let all you guys on something.......Think of the bar and chain as a rope and pulley.
We all understand the labor saving benefit of lifting a weight with a rope on a pulley, now think of a chainsaw drive sprocket pulling a chain over the sprocket nose [pulley] and the cutting effort on the opposite side [push] is reduced.
Here's an old photo of my buddy Oregon field engineer Gary Walrath in 1984 when he held the world record with his 75 H.P. Yamaha hotsaw . Notice his chain is running backwards on the down cut, his chain is throwing chips in a rooster tail for over a 100 feet. Great cutting action with the unobstructed chip flow allowing the best cutting action. Only downfall with the backwards chain rotation is poor ergonomics, Gary wouldn't have able to handle that saw if he wasn't 6' 4", 275 lbs.
Gary was taking a chance if that big ole 1/2" chisel chain was to break or derail, his big black glove on his left hand was padded with lots of Kevlar.

I had my Yamaha hotsaw cutting backwards too but switched to left hand drive with the correct rotation because of difficulty making multiple up down cuts.

 

[Tucker943]

I believe that the chain jumps the bar more easily while backchaining for this reason. The bottom of the bar has chain in motion that are being pulled towards the head of the saw. Like a train pulling its cars from the front. The chain on top of the bar is being pushed. Similar to a line of train cars being pushed from the rear. Now picture resistance at the front of the line of cars. In the case of a chainsaw, that resistance is teeth touching wood. Those cars want to jam up because of the slack in them. They are being slowed by resistance, but continue to be pushed from behind. Those cars will jump the track more easily. Those same cars can have lots of slop in their linkage but when dragging them, that slop is pulled taught. When pushing forward on them, they will want to "bunch up". In the case of a bar rail, they cant bunch up sideways, but they can rise out of the track they're on if the resistance they meet is farther forward on the bar, such as starting to backchain with a portion of the bar up by the sprocket. Now tilt the saw sideways to back chain out a face cut. Those links can rise out of the bar rail and also have a touch of sideways play as the chain technically has the ability to form a sideways belly in it due to some gravity.

Another idea is the fact that on long bars especially with loose chains, the bar gets a droop in it. If the chain hit woods and has slack in it, while the bar is drooped, well, you get the rest.....

 

[HolmenTree]

Forget the rail cars
Even with droop in the chain at WOT the endless loop of chain tightens up, only when a pinch or rotation kick back occurs the chain can derail.
A chain is not only "pushed" it's evenly "pulled" as well.

 

[Tucker943]

I would give a little more thought to what I suggested before denying it. When the chain meets resistance on top of a bar with slack in the chain, a motor pushes the chain forward while wood attempts to slow it. Take a twig and put and index finger on the butt of each end and push gently. Notice it bow. (top side of bar while backchaining).

Take a piece of bowed twig and pull on each end. That illustrates the bottom side of the bar with a loose chain in wood.

Yes, a chain is pushed as hard as it is pulled. But put wood fibers between the push, and the pull, and you create a traffic jam of links in the case of back chaining. If loose chains didn't cause an issue, we would all run them loose.

 

[Tucker943]

Also, a loose chain can jump off a bar without being in wood. Ive have revved a saw with a loose chain many times and had the chain jump. Granted, it has to be a very loose chain, but it can and does happen.

 

[HolmenTree]

Proper chain tension is everything and keeping it sharp by constant touchups. I will run very little slack, like I said earlier only enough where at WOT will keep it tight by the slack being taken up by rolling over the rim onto the bars tail. But tension is very importent to me so I don't mess with a drooping chain if possible and stop to touch my cutters up.
Stihl chain with it's .063 top of the drive links keeps stretching down, Oregon .050, .058 I tension tighter then normal under tough conditions.

 

[Tucker943]

Whether cutting with the top of the bar, or bottom, the force delivered on the saw is either push or pull. The relativity of which has a very strong bearing on how we operate a chainsaw.

I've thrown far more chain while backchaining. Particularly with a loose chain. I have my own ideas on why this is so, but can anybody else here explain it?

It's not rocket science. I'm just curious to see how clear other sawyers in this forum understand the phenomena.

Willard, this is what we are discussing. Feel free to tell both Gerry and I we are delusional if you believe we are. The riddle at hand is "what are some ideas about why its easier to throw a chain while back chaining with a loose chain?"