A different way to sharpen a chain.

[B_Turner]

If I want to look at a cutter that makes great looking shavings,chips, etc. I simply have to look at one of the cutters on one of my chains hot off my ProSharp.

Bottomline of efficient wood removal is sharpness and minimizing fibers severed per unit wood.

As one who makes wood shavings many hours a week, I believe the abovementioned cutters are a near practical limit in cutting efficiency for a sawchain.

As long as you are using a round file or wheel all the dolphins in the world won't swim near well enough to make up that difference in cutting ability. Relatively blunt side cutter and inefficient shape to cut wood.

 

[Crofter]

No doubt that if you go too far outside the normal tooth configuration you can start to see effects in isolation that usually are combined. That said, it appears that you have come to the conclusion that the chain cutters do not normally porpoise. That could be legitimate but it fles in the face of what others have observed. I suggest that some of your conclusions might be circumstantial and you have the cause and effect not entirely meshing. You have to be carefull with evidence that way. Also it is not the best idea perhaps, to state a hypothesis with too much authority until you cross check the conclusions many ways.
Not trying to discourage you from examining the nature of how things work; I have devoted more than a fair share of time to that myself. Just remember that without having total context,that it is easy to watch trees in a breeze and come to the conclusion that it is the waving of their branches that causes the wind to blow.

 

[N9WOS]

No doubt that if you go too far outside the normal tooth configuration you can start to see effects in isolation that usually are combined. That said, it appears that you have come to the conclusion that the chain cutters do not normally porpoise. That could be legitimate but it fles in the face of what others have observed. I suggest that some of your conclusions might be circumstantial and you have the cause and effect not entirely meshing. You have to be carefull with evidence that way. Also it is not the best idea perhaps, to state a hypothesis with too much authority until you cross check the conclusions many ways.
Not trying to discourage you from examining the nature of how things work; I have devoted more than a fair share of time to that myself. Just remember that without having total context,that it is easy to watch trees in a breeze and come to the conclusion that it is the waving of their branches that causes the wind to blow.

And how many car batteries have you ran down by leaving them sit on concrete?

The point is, sometimes I trust conventional wisdom as far as I can throw it. When setting a car battery on the floor, I have had more than the occasional person tell me that it will run it down if I leave it there. And some highly educated people too.

I am still far from sold on the jumping tooth idea. The physics just isn’t there.

Now rock back of the tooth makes sense, but actual liftoff doesn’t.

The only way for it to happen is for there is space for the rake to lift up, then there has to be a non continuous cut to give the tooth space for the angular momentum to launch it and come back down.

If there is no clearance for the rake to lift up on impact with the wood, and no clearance space after impact to come back down after impact and liftoff, then the cutter will remain fully engaged through the length of the cut. It may oscillate after impact and commencement of cutting, but it won’t disengage as long as there is wood in it’s clearance space.

The back end of the link may come off the bar for a split second after impact because of angular velocities, but the cutting force applied to it will quickly push it’s back end back down to the bar as the cut commences. That is with taking into account the need for clearance for it’s front end to start lifting off. If it enters the cut with zero clearance between the wood and the rake then the front won’t lift to allow it to jump in the first place.

Considering that 91 chain has a height from cut edge to pivot point of link of about. 0.3 and a length from rake to back of about 0.5

That gives a mechanical ratio of about 3/5. As long as you apply a down force equal to 3/5 of the chain pull force then the cutters will not lift. If they don’t lift then they can’t jump.

With a maximum mechanical advantage of 3/5 the pull from the engine has no way to lift the bar off the work piece when you are applying more than that amount of force downward. No amount of bouncing back and forth will amplify energy. Law of conservation of momentum comes to mind. The only energy there to lift up the bar is what the motor puts into the chain. If the motor can’t lift the bar of the wood, then the links have no space to bounce.

And as for as deep patterns in the side and clearance of the bar, I was going on the actual drive dogs and the channel size. But the teeth are above that, so it give them more room to move. Actual measured top end (tooth area) play on a new bar an chain is over 50 thousandths which is consistent with even the deepest groves in the wood face. So the chain doesn’t have to come out of the bar even to make the deepest ones I have seen

Considering the normal down force used for normal cutting, the idea of a bounce space is not something I am inclined to believe in.

Just because someone captured an image of a chain doing something under abnormal conditions (very light down force with a bouncing chain) don’t mean that it is how the chain works under normal use.

Just because someone left a battery on concrete and it died, doesn’t mean that the concrete caused the battery to die.

The more I look at the way the teeth cut, the more I am getting the idea that bouncing/jumping teeth are just a wise tale that has been accepted as fact.


:sword:

 

[reachtreeservi]

I thought the first rule of chain sharpening, was that you don't talk about chain sharpening.

LOL.....

 

[056kid]

Whack thread..

 

[Crofter]

Your statements and method of experimenting seems to be a bit short on objectivity! You are attempting to find everything pointing against an intermittent cutting action or porpoising of the cutters.

I agree that it does not have to exist as the only means of having a chain cut wood. I know how I can make a chain cut in that mode but it is not anywhere representative of normal chain.
The first few teeth to contact the wood do not have to rear back to cut! Mark that down! They can each cut the thickness allowed by the raker clearance and in a fraction of a second will have created all kinds of space for the following teeth to start to porpoise between bar and wood. In fact if chain speed is high enough the centrifugal force will be pulling the chain outward with enough force that the chain need not even touch the belly of the bar. Another poster here, timberwolf has a high speed, stop motion photo of a chain showing the drive tangs entirely up out of the groove, and that on a 16 inch bar. There is all the space and more needed to allow for what you insinuate is not possible. Mark that down also!

Now on to your analogy about batteries cement floors and folk lore! That is a perfect parallell to the tree branches and wind! A lead acid battery has a self discharge rate from internal local activity that will cause it to go dead over a period of time whether it is connected to anything or not. It does not discharge through its case so it does not matter whether it sits on a floor, a piece of rubber mat or whatever. Down on a cool floor at a lower temperature will slow the self discharge somewhat compared to a higher room temperature. If a battery sits for any length of time with less than full charge, sulphation of the plates sets in which is practically a permanent limitation of its ability to take a subsequent charge; Perfect example of mis-attributing cause and effect.

To suggest that there is as loose a connection with fact, regarding the cutting action of a chainsaw chain, is a bit of a stretch! Because some people obviously did not understand the lead acid battery does not in itself lend any weight to the argument that the accepted action of a chain saw chain is therefore likely to be incorrect.

 

[Nailgunner]

keep it sharp, keep the angles right, keep it sharp, gauge the rakers now and then and keep them the right height, keep it sharp, Plenty of oil, keep it sharp, Avoid rocks and thereby keep it sharp; Done! No point wearing out the ends of your fingers beyond that. Any questions?

 

[StihltheOne]

:agree2:

 

[N9WOS]

They can each cut the thickness allowed by the raker clearance and in a fraction of a second will have created all kinds of space for the following teeth to start to porpoise between bar and wood.

Once there is space and the teeth are no longer in continuous contact, then where is the down force that you are applying to the bar dissipated? The down force wants to close the gap. The only thing that holds it open is the force on the rakes. Once space is cleared, there is nothing to hold back the down force, so the bar drops to close the space.

In fact if chain speed is high enough the centrifugal force will be pulling the chain outward with enough force that the chain need not even touch the belly of the bar.

The force is experienced where the chain goes around the sprockets. It does not pull outward on the spans of chain in between. They are going in a straight line. When the chain tries to pull out at the ends, it increases the tension on the chain in-between. The chain going around the sprocket on the end is exactly balanced out by the pull from the chain going around the sprocket at the engine.

Another poster here, timberwolf has a high speed, stop motion photo of a chain showing the drive tangs entirely up out of the groove, and that on a 16 inch bar.

That is a good indication that the chain needs tightened :greenchainsaw:

 

[parrisw]

Here is my theroy.

Make the dam chain sharp with the right raker clearance and go cut some DAM WOOD!!!!

They guys I cut with are usually in awe in how my saws always cut really fast. I just know how to sharpen a chain better then they do. At the end of the day, they are always handing me their chains to sharpen up. I guess sometimes it helps that I'm running a saw with 30-40 more cc though, ha ha ha ha ha.

My test is, if its throwing big chips, I did a good job getting it sharp.

 

[litefoot]

What's the porpoise of this thread? And is porpoise a verb?

 

[Justsaws]

It is interesting that all of the chain manufactures have conspired to mislead poor working folks into believing that the product they sell and have sold for decades does not function the way it was designed to function and that their recommended techniques for maintenance are wrong and ineffective.

Do you use a breaker bar on your nuts?

Do your oils and fuels have to be special in order for your saw to function?

Have you ever found yourself asking,"If you could only be a genius then the chains might cut wood?".

Oregon Vanguard?

 

[pgg]

Well, there's still a bit more to this equation, if you're cutting with the top-side of the bar, the chain cuts smoother and cleaner than it does when you're using the bottom-side of the bar. You'll notice it when cutting through branches, use the bottom-side of the bar and the edge of the cut will be rough and 'feathered'. Use the top-side of the bar and the chain leaves a clean smooth non-feathered edge, centrifugal force is affecting the chain and the way it cuts too

 

[Justsaws]

The O.P.s technique is not new or different, it is how the typical chainsaw owner sharpens a chain. He just took the time to rationalize it, for that, I thank you. Do you at least use the correct size file or are you one of those smaller files makes for sharper longer lasting chains people?

Batteries, aquatic mammals, and typical redefined as different, just another day in chainsaw heaven.

Someone needs to blame the Chinese or at least George Bush, mention the 361's ability to never go dull, and ask about modding the muffler so the chain stays sharp longer and this thread will have it all.

I already asked about his nuts, fuels, and oils. Those are covered.

 

[MCW]

I like to get down to the nitty gritty on how things work too, however quantum molecular pythagoran micro physics generally doesn't apply to sharpening chains.....or so I thought.....
Maybe you'd better put the chainsaw sharpening theory to the side for a moment and approach NASA for a job?
If you sharpen a chain and you're happy with the way it cuts, then that's all that matters, no matter how bad it is

 

[John Henry]

This guy is clearly identified as someone who has never had a date.

By the way your statement

QUOTE]The cutting speed of all teeth is controlled by the tooth that cuts the slowest that is in the cutting channel.

seems to be a little off since all cutters are moving at the same speed since they are all attached together. One tooth can't cut slower than the next.

As in all scientific theory, if one of the fundamental assumptions is wrong, the remaining jibberish is to be discarded.[/QUOTE]

He's talking about cutting speed perpendicular to the chain (i.e. depth speed).

I am not about to get into any theories of chain cutting, since I simply don't know a lot about it, but wanted to comment that you all seem a little hard on this guy. And you are doing it without making any objective statements that either agree with or contradict the things he's saying. If there's gibberish in what he's saying, tell us where it is and why it is.

I'm interested in learning about this topic, so was hoping that some of the experts on this stuff come out with some comments one way or the other.

 

[Tzed250]

And how many car batteries have you ran down by leaving them sit on concrete?

The point is, sometimes I trust conventional wisdom as far as I can throw it. When setting a car battery on the floor, I have had more than the occasional person tell me that it will run it down if I leave it there. And some highly educated people too.

I am still far from sold on the jumping tooth idea. The physics just isn’t there.

Now rock back of the tooth makes sense, but actual liftoff doesn’t.

The only way for it to happen is for there is space for the rake to lift up, then there has to be a non continuous cut to give the tooth space for the angular momentum to launch it and come back down.

If there is no clearance for the rake to lift up on impact with the wood, and no clearance space after impact to come back down after impact and liftoff, then the cutter will remain fully engaged through the length of the cut. It may oscillate after impact and commencement of cutting, but it won’t disengage as long as there is wood in it’s clearance space.

The back end of the link may come off the bar for a split second after impact because of angular velocities, but the cutting force applied to it will quickly push it’s back end back down to the bar as the cut commences. That is with taking into account the need for clearance for it’s front end to start lifting off. If it enters the cut with zero clearance between the wood and the rake then the front won’t lift to allow it to jump in the first place.

Considering that 91 chain has a height from cut edge to pivot point of link of about. 0.3 and a length from rake to back of about 0.5

That gives a mechanical ratio of about 3/5. As long as you apply a down force equal to 3/5 of the chain pull force then the cutters will not lift. If they don’t lift then they can’t jump.

With a maximum mechanical advantage of 3/5 the pull from the engine has no way to lift the bar off the work piece when you are applying more than that amount of force downward. No amount of bouncing back and forth will amplify energy. Law of conservation of momentum comes to mind. The only energy there to lift up the bar is what the motor puts into the chain. If the motor can’t lift the bar of the wood, then the links have no space to bounce.

And as for as deep patterns in the side and clearance of the bar, I was going on the actual drive dogs and the channel size. But the teeth are above that, so it give them more room to move. Actual measured top end (tooth area) play on a new bar an chain is over 50 thousandths which is consistent with even the deepest groves in the wood face. So the chain doesn’t have to come out of the bar even to make the deepest ones I have seen

Considering the normal down force used for normal cutting, the idea of a bounce space is not something I am inclined to believe in.

Just because someone captured an image of a chain doing something under abnormal conditions (very light down force with a bouncing chain) don’t mean that it is how the chain works under normal use.

Just because someone left a battery on concrete and it died, doesn’t mean that the concrete caused the battery to die.

The more I look at the way the teeth cut, the more I am getting the idea that bouncing/jumping teeth are just a wise tale that has been accepted as fact.


:sword:

Interesting.

I'll tell you what isn't a wise tale.

Victory.

Since you seem to have made some kind of quatum leap in the understanding of wood cutting, it is time for proof that your theories are correct.

You believe that you have a much better understanding of the mechanics and function of a saw chain, it should be easy for you to file a chain that will cut measurably faster than any other.

Bring a 60 or 72DL chain to a GTG and run it against another chain, on the same saw, in the same wood. If your chain is faster then you might be on to something.

If your chain is not faster then it doesnt matter what you think about how a chain works because all you know how to do is file a slow chain.

Hypothesis-experiment-proof

Are you a Scientist, or a Mad Scientist?




.

 

[MCW]

The more I look at the way the teeth cut, the more I am getting the idea that bouncing/jumping teeth are just a wise tale that has been accepted as fact.
:sword:

You must have better eyes than mine

As Tzed250 said, PROVE IT. There are a lot smarter people than you involved in chain development, testing, and design. Thats not me being negative mate but no matter how smart you think you are, there will always be someone smarter - and they probably work at Carlton, Stihl, Oregon etc etc.

 

[Tzed250]

.


You guys are gonna make me get that video on here aren't you...


.

 

[Crofter]

The force is experienced where the chain goes around the sprockets. It does not pull outward on the spans of chain in between. They are going in a straight line. When the chain tries to pull out at the ends, it increases the tension on the chain in-between. The chain going around the sprocket on the end is exactly balanced out by the pull from the chain going around the sprocket at the engine.




That is a good indication that the chain needs tightened :greenchainsaw:

Well that statement is a good indication that you are either trolling or your powers of observation are such that you are going nowhere with this.

John Henry, your sympathies are rather easily aroused; perhaps your bladder is close to your eyes!