N9WOS
ArboristSite Lurker
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.
Considering the fact that I haven’t frozen to death. That means that I have pretty much come up with my own system to sharpening chains.
I have looked back through the old post as far as I could find and I haven’t really seen anyone mention a system like my system, on this board.
So, if it will help anyone, I will stick my nose out and explain how I have learnt to sharpen chains to get smooth cutting, and consistent cutting speed.
Rules.
First rule. You are sharpening a chain, not individual teeth. The cutting that a tooth does, is more affected by the teeth, and the rakes on the links around it than it is by the rake on the link that the tooth is on it’s self.
Second rule. They move as a group, not as individual teeth.
Third rule. The cutting speed of all teeth is controlled by the tooth that cuts the slowest that is in the cutting channel.
Fourth rule. The incoming wood angle and The travel speed is the sum of the forward speed vector and the cutting speed vector.
Fifth rule. The cutting speed is more of the function of rake height compared to the tooth preceding it on the same side. Not the one following it (the one on the same link.)
The total downward travel speed (cutting speed) is controlled by the rake running in the cutting channel. And logic has it that it is running in the channel left by the preceding tooth. It can’t be running in the channel of the tooth that is on the same link, because it follows behind it .
So, if rake height is set 25 thou below the tooth height, when the chain travels a distance equal to the distance between two cutting teeth on the same side, then the chain will move down 25 thou.
The set of links that have the smallest difference between the rake height and the tooth preceding it will restrict the cutting speed of all the other teeth in the cut.
If you have one short tooth that is only 10 thou above the rake behind it, then all the rest of the teeth will be cutting 10 thou when it’s in the cutting channel. That is even when all the rakes are set to 25 thou below the tooth that is on the same link
The other thing to remember is sharpen each tooth based upon it’s wear, not the wear of any other tooth. You want all teeth to contribute equally to the cut. The wear will tell you if it is taking more or less out of the cut than the other teeth.
The wear can be determined by the flattened leading edge at the very front of the top of the tooth. When you look at it in bright light you will see the glint from it. Sharpen the tooth back till you remove that flattened edge.
If a tooth shows no sign of wear when you sharpen a chain, then don’t sharpen that tooth. Over time, the other teeth will come down to match that tooth. Then you can start to sharpen it as much as the other teeth when it starts to show as much wear.
Remember, we a sharpening a chain, not individual teeth. Just because you have the rake set 25 thou lower than the tooth doesn’t mean it’s going to do any cutting, if it is short enough that it can’t reach the wood.
Just because it’s a new chain doesn’t mean that all the teeth will cut evenly! There is manufacturing variations and tolerances. You will occasionally have a greedy tooth that cuts more than all the rest. That one will need to be filed down more than the other ones until they start wearing evenly as a set.
And some times you get a chain which has one side that has the teeth sticking out higher. So one side will have to be sharpened a little more each time you sharpen it until it starts evening out.
A good (accidental) rock grind is a quick way to find out which teeth are sticking out more. It’s obvious if you have any tall teeth after you hit a rock.
If you don’t want to take the time to set each rake by the height of the tooth in front, then it is easier to just grind the rakes down as a group. Not based on the height of the tooth in front of it.
I normally just sharpen the teeth based on wear until the chips start getting small, then I bring the rakes down as a set. Bring all the rakes down the same amount. Get the rakes about 30 thou below the average tooth height. If the chain has been sharpened evenly, then there should be little difference among the height of the teeth on the chain. Given the occasional rock damaged tooth that is shorter than the rest.
On the occasional rock damaged tooth, you probably want to take of a little on the rake following it so it won‘t slow down the cutting speed.
The cutting area is separated into three zones. The right tooth side, the left tooth side, and the overlap area. The right and left tooth side take 25 thou each pass, while the overlap area gets a 12 thou cut each pass because it is cut by both sides.
Lets look at the cutting done by a chain of teeth on one side.
Lets say you have all the rakes set to 25 thou below the tooth on the same link, but one of the teeth is 10 thou shorter than the rest.
N= normal
S= short
(amount of cut in thousandths)
N ,N ,N ,S , N , N , N
15, 15, 15, 5, 25, 15, 15.
The only tooth that is cutting the full 25 thou is the one behind the short tooth. Cut speed is set by the by the smallest difference in height, that is between the short tooth and the rake on the one behind it. That is 15 thousandths per chain travel equal to the distance between the teeth on the same side.
If you set rake height based on the tooth preceding it. Then this is the cutting pattern.
N ,N ,N ,S , N , N , N
25, 25, 25, 15, 35, 25, 25.
Considering the wear will eat away at the tooth following the short one, and the short one will wear less, then after sharpening, the cutting pattern will start to look like this.
N ,N ,N ,S , N , N , N
25, 25, 25, 17, 31, 27, 25.
Then
N ,N ,N ,S , N , N , N ,N
25, 25, 25, 20, 27, 27, 26, 25
All the time maintaining a constant average of 25 thou per tooth, cutting speed.
If you sharpen based on wear with all the rakes set to the same height then cutting speed will be limited to the shortest tooth. But as you file down based on wear, then all the teeth should get close to the same height above the rakes and wear/cut evenly.
All you have to pay attention to is a short (previously damaged tooth) that you will have to cut the rake down behind it a little more than the rest so it don’t affect cutting speed when it is in the cut channel.
As I previously stated.
“I normally just sharpen the teeth based on wear until the chips start getting small, then I bring the rakes down as a set. Bring all the rakes down the same amount. Get the rakes about 30 thou below the average tooth height. If the chain has been sharpened evenly, then there should be little difference among the height of the teeth on the chain. Given the occasional rock damaged tooth that is shorter than the rest.
On the occasional rock damaged tooth, you probably want to take of a little on the rake following it so it won‘t slow down the cutting speed.”
The reason I state “Bring them down the same amount” instead of worrying about measuring their height compared to anything else is…… The rake that rides the wood the most, and slows down the cutting speed the most is the one that wears the most. So, after a good amount of cutting, then all the rakes should be close to the same height below the preceding tooth. You want to keep the height difference the same from set to set, so you just bring all them down the same amount. (The same number of passes with a flat file.)
I can make up a couple pictures to illustrate what I am talking about if anyone wants.
Considering the fact that I haven’t frozen to death. That means that I have pretty much come up with my own system to sharpening chains.
I have looked back through the old post as far as I could find and I haven’t really seen anyone mention a system like my system, on this board.
So, if it will help anyone, I will stick my nose out and explain how I have learnt to sharpen chains to get smooth cutting, and consistent cutting speed.
Rules.
First rule. You are sharpening a chain, not individual teeth. The cutting that a tooth does, is more affected by the teeth, and the rakes on the links around it than it is by the rake on the link that the tooth is on it’s self.
Second rule. They move as a group, not as individual teeth.
Third rule. The cutting speed of all teeth is controlled by the tooth that cuts the slowest that is in the cutting channel.
Fourth rule. The incoming wood angle and The travel speed is the sum of the forward speed vector and the cutting speed vector.
Fifth rule. The cutting speed is more of the function of rake height compared to the tooth preceding it on the same side. Not the one following it (the one on the same link.)
The total downward travel speed (cutting speed) is controlled by the rake running in the cutting channel. And logic has it that it is running in the channel left by the preceding tooth. It can’t be running in the channel of the tooth that is on the same link, because it follows behind it .
So, if rake height is set 25 thou below the tooth height, when the chain travels a distance equal to the distance between two cutting teeth on the same side, then the chain will move down 25 thou.
The set of links that have the smallest difference between the rake height and the tooth preceding it will restrict the cutting speed of all the other teeth in the cut.
If you have one short tooth that is only 10 thou above the rake behind it, then all the rest of the teeth will be cutting 10 thou when it’s in the cutting channel. That is even when all the rakes are set to 25 thou below the tooth that is on the same link
The other thing to remember is sharpen each tooth based upon it’s wear, not the wear of any other tooth. You want all teeth to contribute equally to the cut. The wear will tell you if it is taking more or less out of the cut than the other teeth.
The wear can be determined by the flattened leading edge at the very front of the top of the tooth. When you look at it in bright light you will see the glint from it. Sharpen the tooth back till you remove that flattened edge.
If a tooth shows no sign of wear when you sharpen a chain, then don’t sharpen that tooth. Over time, the other teeth will come down to match that tooth. Then you can start to sharpen it as much as the other teeth when it starts to show as much wear.
Remember, we a sharpening a chain, not individual teeth. Just because you have the rake set 25 thou lower than the tooth doesn’t mean it’s going to do any cutting, if it is short enough that it can’t reach the wood.
Just because it’s a new chain doesn’t mean that all the teeth will cut evenly! There is manufacturing variations and tolerances. You will occasionally have a greedy tooth that cuts more than all the rest. That one will need to be filed down more than the other ones until they start wearing evenly as a set.
And some times you get a chain which has one side that has the teeth sticking out higher. So one side will have to be sharpened a little more each time you sharpen it until it starts evening out.
A good (accidental) rock grind is a quick way to find out which teeth are sticking out more. It’s obvious if you have any tall teeth after you hit a rock.
If you don’t want to take the time to set each rake by the height of the tooth in front, then it is easier to just grind the rakes down as a group. Not based on the height of the tooth in front of it.
I normally just sharpen the teeth based on wear until the chips start getting small, then I bring the rakes down as a set. Bring all the rakes down the same amount. Get the rakes about 30 thou below the average tooth height. If the chain has been sharpened evenly, then there should be little difference among the height of the teeth on the chain. Given the occasional rock damaged tooth that is shorter than the rest.
On the occasional rock damaged tooth, you probably want to take of a little on the rake following it so it won‘t slow down the cutting speed.
The cutting area is separated into three zones. The right tooth side, the left tooth side, and the overlap area. The right and left tooth side take 25 thou each pass, while the overlap area gets a 12 thou cut each pass because it is cut by both sides.
Lets look at the cutting done by a chain of teeth on one side.
Lets say you have all the rakes set to 25 thou below the tooth on the same link, but one of the teeth is 10 thou shorter than the rest.
N= normal
S= short
(amount of cut in thousandths)
N ,N ,N ,S , N , N , N
15, 15, 15, 5, 25, 15, 15.
The only tooth that is cutting the full 25 thou is the one behind the short tooth. Cut speed is set by the by the smallest difference in height, that is between the short tooth and the rake on the one behind it. That is 15 thousandths per chain travel equal to the distance between the teeth on the same side.
If you set rake height based on the tooth preceding it. Then this is the cutting pattern.
N ,N ,N ,S , N , N , N
25, 25, 25, 15, 35, 25, 25.
Considering the wear will eat away at the tooth following the short one, and the short one will wear less, then after sharpening, the cutting pattern will start to look like this.
N ,N ,N ,S , N , N , N
25, 25, 25, 17, 31, 27, 25.
Then
N ,N ,N ,S , N , N , N ,N
25, 25, 25, 20, 27, 27, 26, 25
All the time maintaining a constant average of 25 thou per tooth, cutting speed.
If you sharpen based on wear with all the rakes set to the same height then cutting speed will be limited to the shortest tooth. But as you file down based on wear, then all the teeth should get close to the same height above the rakes and wear/cut evenly.
All you have to pay attention to is a short (previously damaged tooth) that you will have to cut the rake down behind it a little more than the rest so it don’t affect cutting speed when it is in the cut channel.
As I previously stated.
“I normally just sharpen the teeth based on wear until the chips start getting small, then I bring the rakes down as a set. Bring all the rakes down the same amount. Get the rakes about 30 thou below the average tooth height. If the chain has been sharpened evenly, then there should be little difference among the height of the teeth on the chain. Given the occasional rock damaged tooth that is shorter than the rest.
On the occasional rock damaged tooth, you probably want to take of a little on the rake following it so it won‘t slow down the cutting speed.”
The reason I state “Bring them down the same amount” instead of worrying about measuring their height compared to anything else is…… The rake that rides the wood the most, and slows down the cutting speed the most is the one that wears the most. So, after a good amount of cutting, then all the rakes should be close to the same height below the preceding tooth. You want to keep the height difference the same from set to set, so you just bring all them down the same amount. (The same number of passes with a flat file.)
I can make up a couple pictures to illustrate what I am talking about if anyone wants.
woah i just throw em on the grinder at my dads lol. welcome btw
opcorn: 
