Bucking Question

[sierratree]

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

yes...you're probably correct..........an old timer passed this along to me. at the time it sounded good. but now after thinking about it, doesn't make much sense........

 

[HolmenTree]

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?"

Basically this whole thread was based on the OP [Coreys] question why is the up cut seem faster before I chimed in, I'm trying to get back to that original question with my answer on post#44
If you want an answer for Jerrys question about derailing, I'd say running long bars in the PNW would see a lot of derailing on back chaining with those long bars easily flexing and throwing their chains.........but I thought the original question why it seems easier to cut back chaining was more important so let's go back to my rope and pulley theory in post 44

 

[woodworkingboy]

I got a thing too about loose chain, it's like fingernails across a blackboard, but around here it sure doesn't seem to bother a lot of folks.

 

[MasterBlaster]

I hate it when clutchs go out...

 

[HolmenTree]

I got a thing too about loose chain, it's like fingernails across a blackboard, but around here it sure doesn't seem to bother a lot of folks.

I used to have an issue with chain derailing back in the 1970s/80s when the logging company I worked for forced us to use the small diameter safety nose bars, like the Oregon banana / Double Guard tips or the Windsor Mini Pro bars. When we were later allowed to run standard tips [after protest from Stihl and the majority of users] derailing was no longer an issue.

Longer bars means more chance of chain derailing, probably the reason why back chaining is regulated in the B.C. forestry industry. Too many barber chair accidents due to chain derailing on the back cut with those long bars.

 

[cory]

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.

So Gerr, what is your theory on this?

 

[gf beranek]

The slack build up on top of the bar while back-chaining is the leading culprit to the chain running off the tip. Happens most frequently while back-chaining limbs and brush. That's my take on it, Cory.

Though I must add, one time I had a chip in the rail my bar and it would lead my chain off the tip every time I back-chained, and let off on the cut. It took me a few minutes to figure out what the hell was going on. I turned the bar over and the problem was fixed.

Funny all the situations we get into and learn from. The simple ones are the most enlightening sometimes.

 

[Tucker943]

The slack build up on top of the bar while back-chaining is the leading culprit to the chain running off the tip. Happens most frequently while back-chaining limbs and brush. That's my take on it, Cory.

Though I must add, one time I had a chip in the rail my bar and it would lead my chain off the tip every time I back-chained, and let off on the cut. It took me a few minutes to figure out what the hell was going on. I turned the bar over and the problem was fixed.

Funny all the situations we get into and learn from. The simple ones are the most enlightening sometimes.

That is EXACTLY what I was trying to explain. Jerry was able to orate it in one sentence. Jerry if you thumb back to my explanation, you'll see we are on the same page.

 

[gf beranek]

Yes, indeed, Tucker. Over the years I've watched it happen numerous times. A slow-mo video of it would be neat to watch, I think.

 

[squisher]

I'm not seeing it myself. If slack builds up on the top of the bar while cutting with the top. Why wouldn't it still build up while cutting with the bottom of the bar? And why not more so as there would be more chain available on the top to build up what slack could develop?

 

[Marc-Antoine]

It's difficult to tell without slowmotion, but I think there are probably some sort of waves and resonance in the chain's motion. Simply by that, with enough slack, the drivers could repeatedly jump out of the groove (at least, partially) and go back in. A slight lateral movement of the bar or wood, and the drivers can't found the groove again and slide out of the bar (or is more easily pushed out sideway).

The chain is straightened between the wood and the sprocket, as the sprocket pulls the chain and the wood keeps holding it.
With wood on the lower side, the straightened portion of the chain is short, say 1/4 of the total chain's length. The slack is spread on the 3/4 length between the sprocket toward the wood. So there is less slack per driver, aka less possibility for this one to jump out of the groove.
With wood on the upper side, the straightened portion of the chain is long, like the 3/4 chain's length, going around the bar nose. In this case, the slack is confined only on 1/4 of the length, each driver in this area has more liberty and is more prone to wobble / jump out of the groove.

It's only a thought, I don't have evidence of that.

 

[Tucker943]

YES. This is what I was laughed at for suggesting.

 

[Andyshot]

I know this is an old post, but what is missing in the equation is friction and oil. The top of the bar gets the oil first before it flings the excess off of the tip. Less friction equals more force to the teeth for cutting. The drier bottom track has hardly any friction since it’s just hanging in the groove.

 

[Nutball]

Good thought, it all adds up. I know burying the bar can be the hardest part if the tip is always trying to pull opposite of the cut.

 

[Tree09]

Welcome Andy!

 

[MasterBlaster]

Welcome to the TreeHouse, Andy! Make yourself at home!

 

[flushcut]

Welcome!