A different way to sharpen a chain.

[N9WOS]

N9WOS, that is very impressive! Please continue, I'd like to read more. Do you change your rules from softwood to hardwood?

How you change the sharpening pattern from soft wood to hard wood depends on if you want the teeth to lift when they go through the cut channel.

The cutting point is elevated above the support point. The chain is flexible, so when it is in the cut, and there isn’t enough force to keep the cutting link seated, the front of the tooth will lift up until the rake is dragging the wood.

Non lifting. There is enough down force and downward travel to keep all the links with the teeth fully seated, and in full cut.

Full cut is where you can put more down force on the bar and it doesn’t bog down the motor any more, or increase the cutting speed. That means that all links are solidly seated in the bar, running solidly on the rakes and all teeth are getting there full 25 thou. That is what my first post detailed. A way to sharpen a chain to maintain an even full cut for maximum cutting speed.

Lifting. There isn’t as much force down, as there is pulling force. So the front of the cutting links start to come up off the bar.

The teeth take less of bite because they are only taking a fraction of the full 25 thou. Thus, not maintaining maximum cutting speed.

If you look at the layout of the teeth, you will see that when it’s new the teeth can lift up to 30 to 40 thou and still remain actively cutting. Any more than that, then the rake will come above the cutting edge, the tooth will lose contact, and the tooth will drop back down.

The links at the end of the bar close to the motor will tend to lift less because of the pull force from all the other links that tend to keep it fully seated.

The lifting action helps compensate for height differences in teeth when the chain is new.

But as teeth wear, the cutting edge moves back to the back end of the link. So, when the front of the link lifts, then the actual cutting edge (at the back of the link) no longer comes up with it. So it don’t make a difference if the links are lifting or not.

For soft wood that takes little pull force per tooth, then you assume no lifting. Thus my method of sharpening in the earlier post to make sure all teeth stay fully into the cut.

Hard woods that take a lot of pull per tooth, then you can sharpen for lifting when the chain is new and the saw doesn’t have enough gumption to pull the chain when the teeth are at full cut. For that mode of cutting, you can set the rake height based on the tooth behind it. (traditional method)

But as the chain comes to the end of it’s life, then you need to start setting the rakes based on the tooth in front of them. That is because the link doesn’t really have any lifting action.

For hardwoods with a chainsaw that can pull the chain in full cut, then you can go for the method in my first post.

 

[N9WOS]

Actually it's both:
Cutting speed is distance cut per unit time

"Inches of wood per layer x Number of layers or passes per unit time (rpm)."

I never read sharpening books either. I watched my Pa and did what I reckoned he did and he just slapped my hand when I did it wrong! I guess he never read any education books either, actually he did but later on in his life. . . .

Yes, but I am assuming for all practical purposes that the chainsaw is big enough to pull the chain at close to full speed, so travel speed down the bar can be ignored for practical purposes.

So the equation drops down to how much the teeth can remove each pass.

:sword:

 

[NDtreehugger]

Having ran chainsaws for over 16 years to cut firewood for are own consumption. Having never taken a chain in for sharpening in those 16 years. And having a dad to learn from that really never could sharpen a chain properly. And never having any books or the internet that told me how to sharpen a chain properly.

WTF

please make that a sixpack


Heres the way I look at Chainsaw Chain..

if its stihl use a grinder, if its a cheap chain use a grinder, if your in the field use a new chain and if it gets unsharp ues a new chain (thats the beer talking) then use a grinder then if you have a file and its a cheap chain ues a file the beer again. by the way I now cross eyed and out of beer so dmnit

 

[Crofter]

How you change the sharpening pattern from soft wood to hard wood depends on if you want the teeth to lift when they go through the cut channel.

The cutting point is elevated above the support point. The chain is flexible, so when it is in the cut, and there isn’t enough force to keep the cutting link seated, the front of the tooth will lift up until the rake is dragging the wood.

Non lifting. There is enough down force and downward travel to keep all the links with the teeth fully seated, and in full cut.

Full cut is where you can put more down force on the bar and it doesn’t bog down the motor any more, or increase the cutting speed. That means that all links are solidly seated in the bar, running solidly on the rakes and all teeth are getting there full 25 thou. That is what my first post detailed. A way to sharpen a chain to maintain an even full cut for maximum cutting speed.

Lifting. There isn’t as much force down, as there is pulling force. So the front of the cutting links start to come up off the bar.

The teeth take less of bite because they are only taking a fraction of the full 25 thou. Thus, not maintaining maximum cutting speed.

If you look at the layout of the teeth, you will see that when it’s new the teeth can lift up to 30 to 40 thou and still remain actively cutting. Any more than that, then the rake will come above the cutting edge, the tooth will lose contact, and the tooth will drop back down.

The links at the end of the bar close to the motor will tend to lift less because of the pull force from all the other links that tend to keep it fully seated.

The lifting action helps compensate for height differences in teeth when the chain is new.

But as teeth wear, the cutting edge moves back to the back end of the link. So, when the front of the link lifts, then the actual cutting edge (at the back of the link) no longer comes up with it. So it don’t make a difference if the links are lifting or not.

For soft wood that takes little pull force per tooth, then you assume no lifting. Thus my method of sharpening in the earlier post to make sure all teeth stay fully into the cut.

Hard woods that take a lot of pull per tooth, then you can sharpen for lifting when the chain is new and the saw doesn’t have enough gumption to pull the chain when the teeth are at full cut. For that mode of cutting, you can set the rake height based on the tooth behind it. (traditional method)

But as the chain comes to the end of it’s life, then you need to start setting the rakes based on the tooth in front of them. That is because the link doesn’t really have any lifting action.

For hardwoods with a chainsaw that can pull the chain in full cut, then you can go for the method in my first post.

I see some food for thought here. The theory of how a chain actually cuts if you could be view it in 3D slow motion would be a lot different than we usually think of it. I think Z250 posted some video here a number of years back. I like to think of it as a string of cutting kites being pulled one behind the other with each one having some limited individual motion but still influenced by whatever its front and rear partners are doing. I think N9WOS has made some interesting observations that tie in with other things we have read like progressive raker lowering as the chain wears back and leverage and angle of attack change relationships. The chattering in hard wood with too much raker clearance is spot on.

The normal intermittent or bobbing action of each cutter can be influenced by raker clearance, chain tension, how far back the tooth is worn, amount of hook and sharpening angles, whether upcut or down, and by the amount of pressure applied to the saw. If you use anything within reasonable recommended dimensions and dont get ridiculously extreme in tooth sizes you may never in a life of cutting run into it or have to worry about why.

Some of those things become much more important if you are trying to make a competition chain but I guess if you do it right you really dont have to know why it works there either. One thing you will always see is the cutter taken back to the rear rivet.

Normally a cutter makes a bit of a scoop sideways at the same time it makes its shallow scoop downwards. How hard the chain is dragging its top cutter affects how much it skews out sideways too. I will attach a picture of different cuts in the same wood with only minor changes in raker and alteration of the side cutter that changed its way of cutting from intermittent to almost continuous pulls across the piece. The wood was red maple and the chain square ground. Just something I was playing with at the time. I can spend a lot of time trying to figure out what makes things tick, not that I have capitalized on much of it though.

I had not thought of the significance of the raker height of preceding same side cutter because I just dont get them that out of whack unless it is my stump and nail chain and it doesnt cut fast or smooth anyway! I think his hypothesis makes sense for a chain with higher rakers and being pushed on, more so than one with more aggressive raker and less chain pressure.

 

[Cedarkerf]

Sounds like must cost a lotta money for a chain to put this much thought into it. My Grandad dropped out of the sixth grade and figured out how to sharpen a chain well enough to cut this tree down in less than a day.

 

[cmetalbend]

Sounds like must cost a lotta money for a chain to put this much thought into it. My Grandad dropped out of the sixth grade and figured out how to sharpen a chain well enough to cut this tree down in less than a day.

That's interesting, What type of tree is that? Think I'd need a little more than my 280 echo for that. LOL

 

[Cedarkerf]

Douglas Fir. Orygun 1950s

 

[N9WOS]

Here is a start on the illustrations.

How a lifting tooth works.

The example link in these pics is really small compared to the cut. It’s only 210 thousandths long and 120 thousandths tall, with a 25 thou cut. That way it magnifies the angles to make it easier to see.

Tooth- New tooth 25 thou cut

Old tooth- end of life tooth with same 25 thou cut.

Lift- new tooth close to maximum lift of 43 thou. 7 thou cut in that position.

Old tooth lift. Old one close to maximum lift of 19 thou. 7 thou cut in that position.

If you have the too low of angle on the cutting face then when the tooth lifts, the angle will go vertical and the chain will start jumping.

 

[Stihl 041S]

How do you keep the lift constant? It would change with load, chain temp, sharpness of the cutters,amount of oil.........

 

[Crofter]

How do you keep the lift constant? It would change with load, chain temp, sharpness of the cutters,amount of oil.........

And chain tension, up cut / downcut etc. Probably, no, certainly more of theoretical than otherwise and I cant see a lot of people applying it in the field, but I do find it interesting.

Kind of like discussing all the things that can contribute to causes or cures of chatter in machining.

The only time I have really come across some weird chain tooth configurations is when someone was trying to compensate for a running off cut and was not attacking the real cause. I have not tried it myself but have seen it claimed that a chain could have longer cutters one side than the other and as long as the rakers were set proportionally it would still cut straight.

 

[Stihl 041S]

Crofter;
I'm running a machine as I read this thread. Machine variables made me think of such things. Insert companys take all things and give us a workable average.
Good reamers have uneven spacing on the teeth to keep vibration down. Formula in the Machinery Handbook for it.
.
You can't cover all the fine points and make money.

 

[ray benson]

Took this off the Carlton site.

 

[777ER]

You mean like in the way the attached image shows?

Also see page 19 and 20 of this link:
http://www.sawchain.com/images/complete book.pdf

I think what you're talking about is relative to the hinge point of the cutter itself.

 

[Slamm]

Thinking of the chain as a "team" and now Dolphins in the ocean. Perfect.

It's all getting clearer ...... no really it is, LOL.

Sam

 

[bigjake]

Man my brain is smokin. The last pic did clear it all up .And how many people
here are wearing tin foil hats LOL or 10

 

[Tzed250]

The OP is smart, but making guesses.

I do have the video that Frank mentioned, but I have never been able to post it here(still VHS).

The video shows the cutters diving in and out of the fiber in a sine wave motion. They do not stay seated on the bar rail.

Let's not forget that the real work done by the cutter is done with the side plate, not the top plate.

Pulling the fibers away from each other is easy. Severing the fibers is much harder.

 

[Tzed250]

Crofter;
I'm running a machine as I read this thread. Machine variables made me think of such things. Insert companys take all things and give us a workable average.
Good reamers have uneven spacing on the teeth to keep vibration down. Formula in the Machinery Handbook for it.
.
You can't cover all the fine points and make money.

Haha!!! Me too!!!

Surface speed X feed/tooth= feedrate

 

[777ER]

The video shows the cutters diving in and out of the fiber in a sine wave motion. They do not stay seated on the bar rail.

So this brings up a issue about chain tension.
Like does a slightly loose chain cut more and does 'dolphins swiming' on a larger scale?
On the other hand, a loose chain can also create problems staying on the bar or has a tendency to throw itself off.
Where a chain too tight will do less cutting as a loose one?

 

[Stihl 041S]

Tzed250;
You mean all you got to back up you hair brained ideas is a bunch of facts?????




Well okay then, very nice post. mongo sorry.

 

[stihl only]

I only use the Stihl 33SSC chain. It is a greatly improved design with shark swimming cutters!