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Is what this fella is saying true about “tooth length”

Started by HemlockKing, September 23, 2021, 07:18:07 AM

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HemlockKing

https://m.youtube.com/watch?v=Ca-0Yd6uAKc  At 8:25 he mentions the tooth need to be the same? I kind of chuckled as doesn't a raker gauge fix that? Some of my chain tooth's are filed way down and some still 3/4 life, cuts great, all depends which teeth get damaged worse if I hit rock, i am correct in that it doesn't matter right? 
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teakwood

Quote from: HemlockKing on September 23, 2021, 07:18:07 AMSome of my chain tooth's are filed way down and some still 3/4 life, cuts great


then you will be amazed how great a chain cuts when you file it correctly!

the cutters should be all the same length, more or less, it's hard to achieve this. all persons have a strong and a weaker arm, i have to do one stoke more on the right side every second filing because my right files weaker than the left.
if one tooth is significantly longer than the others than this guy is pushed in alot harder in the cut and wants to do more cutting than the shorter tooth, result: a chain that doesn't cuts perfect.

if you hit a rock then you file all the tooth back to the same length of this shortened tooth  
National Stihl Timbersports Champion Costa Rica 2018

HemlockKing

Quote from: teakwood on September 23, 2021, 07:52:04 AM
Quote from: HemlockKing on September 23, 2021, 07:18:07 AMSome of my chain tooth’s are filed way down and some still 3/4 life, cuts great


then you will be amazed how great a chain cuts when you file it correctly!

the cutters should be all the same length, more or less, it's hard to achieve this. all persons have a strong and a weaker arm, i have to do one stoke more on the right side every second filing because my right files weaker than the left.
if one tooth is significantly longer than the others than this guy is pushed in alot harder in the cut and wants to do more cutting than the shorter tooth, result: a chain that doesn't cuts perfect.

if you hit a rock then you file all the tooth back to the same length of this shortened tooth  
Well I do go through chains fairly often so I know what a “new correct” chain feels like, I will need someone to explain the science on this, maybe it does make a difference and hurt performance but not enough to actually chase each tooth down to the lowest tooth? As that takes much more
Time

Edit: on second thought I can see how it would hurt performance, 2 high points, and a low tooth in the middle, skip chaining basically. Even if the rakers are filed the tooth would chisel the same depth but on a whole the smaller tooth will be lower profile. 
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teakwood

Quote from: HemlockKing on September 23, 2021, 08:03:09 AMI know what a "new correct" chain feels like


For all you guys out there, if you think a new out of the box chain cuts super fast then you haven't perfected your sharpening skills yet!

a chain filed properly cuts better than out of the box, at least the first third of its life. 
National Stihl Timbersports Champion Costa Rica 2018

mike_belben

what happens as the tooth shortens in length is that it also shortens in height.  now when the cutter hits fiber it curls back on its heel like a kid on a skateboard dragging tail, except instead of the tail being the angle limiter, in our case it is the raker.  the cutter point hits wood and tries to wheelie over backwards but the raker hits wood ahead of the cut and prevents it, holding that wheelie angle theoretically consistent so that the tooth angles become the best cutter point possible for the severing of fibers.  this is very similar to the fine angles on drill points, lathe tools, planer knives and so forth.  different angles are better at different things. a fine edge is a great cutter with short life.  a blunt edge isnt a great cutter but its slower to round over.  either way, they work best when hitting the wood at the right rake angle which is dictated by the height of the raker.  

now as your tooth gets shorter the raker has to get a lot shorter for the cutter point to hit the wood at the same attack angle as it did when new.  so the concept is adjusting raker height to make an old tooth still peel as efficiently as a new tooth.  race chain guys are probably the most qualified to tell you that a tooth can only get so sharp.  after that its clearance space to fit the curls of wood and blow them out of the kerf.  a chain is a cutter and a conveyor belt after all.


anyways, we could talk fine details all day on this and i predict at least 4 pages before food comes up...but the truth is -imho anyways- it dont really matter for most people. the chain and its filing is just one part of a web of details.  if youve got a few cutters that arent pulling their weight then the next one in line will and youll cut that tree 3 seconds slower.  there are guys who can win a hotsaw cookie contest and making a living selling ported jugs out of a shed yet probably  barberchair half the trees they fell and buck them all wrong.  there are guys who can slay prime veneer perfectly and probably dont fuss very much about the details, just cut a few seconds longer.  im sure theres every shade in between and what does it really matter?  in the grand scheme of things not very much.  if it bothers you fix it, if it doesnt keep sawing.  itll come down sooner or later. beavers dont worry about rake angles but not many trees escape their persistence. im sure many a felling axe had a chip in it but they slayed the giants to spite that chip anyway.

none of us will be called up to judgement to give account on the sins of our saw chains.
Praise The Lord

HemlockKing

Quote from: teakwood on September 23, 2021, 08:34:24 AM
Quote from: HemlockKing on September 23, 2021, 08:03:09 AMI know what a "new correct" chain feels like


For all you guys out there, if you think a new out of the box chain cuts super fast then you haven't perfected your sharpening skills yet!

a chain filed properly cuts better than out of the box, at least the first third of its life.
Thank you teakwood. I've been humbled today  ;D I will try from now on to keep the same size tooth.
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HemlockKing

Quote from: mike_belben on September 23, 2021, 08:46:21 AM
what happens as the tooth shortens in length is that it also shortens in height.  now when the cutter hits fiber it curls back on its heel like a kid on a skateboard dragging tail, except instead of the tail being the angle limiter, in our case it is the raker.  the cutter point hits wood and tries to wheelie over backwards but the raker hits wood ahead of the cut and prevents it, holding that wheelie angle theoretically consistent so that the tooth angles become the best cutter point possible for the severing of fibers.  this is very similar to the fine angles on drill points, lathe tools, planer knives and so forth.  different angles are better at different things. a fine edge is a great cutter with short life.  a blunt edge isnt a great cutter but its slower to round over.  either way, they work best when hitting the wood at the right rake angle which is dictated by the height of the raker.  

now as your tooth gets shorter the raker has to get a lot shorter for the cutter point to hit the wood at the same attack angle as it did when new.  so the concept is adjusting raker height to make an old tooth still peel as efficiently as a new tooth.  race chain guys are probably the most qualified to tell you that a tooth can only get so sharp.  after that its clearance space to fit the curls of wood and blow them out of the kerf.  a chain is a cutter and a conveyor belt after all.


anyways, we could talk fine details all day on this and i predict at least 4 pages before food comes up...but the truth is -imho anyways- it dont really matter for most people. the chain and its filing is just one part of a web of details.  if youve got a few cutters that arent pulling their weight then the next one in line will and youll cut that tree 3 seconds slower.  there are guys who can win a hotsaw cookie contest and making a living selling ported jugs out of a shed yet probably  barberchair half the trees they fell and buck them all wrong.  there are guys who can slay prime veneer perfectly and probably dont fuss very much about the details, just cut a few seconds longer.  im sure theres every shade in between and what does it really matter?  in the grand scheme of things not very much.  if it bothers you fix it, if it doesnt keep sawing.  itll come down sooner or later. beavers dont worry about rake angles but not many trees escape their persistence. im sure many a felling axe had a chip in it but they slayed the giants to spite that chip anyway.

none of us will be called up to judgement to give account on the sins of our saw chains.
Thank you for the explanation. I'm learning some today. Basically try to keep the same length if you can help it, but don't let it bother you so much. I'm not into a race or anything, I can still cut fast. 
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HemlockKing

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Hogdaddy

My experience...  a new chain will not cut as well as a correctly sharpened chain by a right smart. Yes you need to keep everything equal on a chain, but teeth being shorter than the other teeth does not effect the cutting of the chain. Where you get into trouble is when you get your rakers out of sorts. And, I can get a chain to cut nearly just as well when almost used up, as I can a second or third sharpening. just my experience and my .02 worth 
If you gonna be a bear, be a Grizzly!

HemlockKing

I have only had 2 chains that I know of I had to sharpen out of the box, I inspect the cutters before hand, I know you can only see so much, but I throw it on the chips are large, the saw pulls, in happy enough
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Ianab

Mikes explanation of how the raker controls the tooth action is correct. There is some high speed video around showing how each cutting link "see saws" through the cut, basically bouncing off the raker and so pulling a chip every inch or so of it's travel as it rocks through the wood. If one tooth is a little shorter and lower, it's still going to have that rocking motion, and still pull chips, just maybe slightly less?


Now if everything on the chain is perfectly matched it makes sense that that chain can now be working at 100%. So if you are chainsaw racing, and spend an hour perfecting the chain sharpness to gain 1 second in the cut, then matching everything up perfectly might be what wins the competition.  A slightly mismatched set of cutters can still cut well, just not at 100%, so you come 2nd in the race.


New chain compared to resharpened? It's certainly possible to resharpen a chain "better than new". The chain is mass produced, and may not be perfect out of the box. Also the exact geometry of the cutter for a certain cut will depend on the saw (power and bar length) and the wood (hardness and log size etc). While the factory chain is set up for some average situation. It will work pretty well in most cases, but again that doesn't mean it's perfect, and can't be improved a little. 


My take on sharpening is you should always be able to get the chain "good as new", and keep it that way for most of it's life. An Expert sharpener is someone that can get it to cut Better than new.  I'm not overly worried about having cutter lengths exact, I don't think it makes enough difference to justify the time it takes. That doesn't mean the guys matching their cutters up are wrong, they likely DO get slightly better cutting performance, but is it enough to justify the time spent?
Weekend warrior, Peterson JP test pilot, Dolmar 7900 and Stihl MS310 saws and  the usual collection of power tools :)

ehp

Believe me when I say on race chains its for sure not an hour to sharpen , on a 88 driver high tooth bike chain its hours and hours    on a single chain and your not going to gain a second , your looking for .1 of a second over the other chains . There is alot of theory in on how to make a chain cut better , some of the better race filers believe that every 6 tooth should be different on each side to stop the wave the chain gets when every tooth is the same and by making the 6 tooth different it does stop the wave . There is a lot of other stuff that goes into it as well 

teakwood

Quote from: HemlockKing on September 23, 2021, 08:58:35 AMThank you teakwood. I've been humbled today   I will try from now on to keep the same size tooth.


It wasn't my intention to humble you, we all learn something new every day. i still have a hard time to make a chain cut right when there is only a third of the cutter left, something is off, maybe my angles or cutter length, i don't know for sure.

If i damage on tooth on the chain i won't file down the whole chain, that just doesn't makes sense and takes way too long. normally when you hit a rock it will damage at least 4 tooth on one side, if you need 6 strokes to get them to cut again then i give all the others 4 strokes, normally i get away with 2 or maybe 3 strokes to touch up a chain.  As mike explained, the chain still cuts very good.
National Stihl Timbersports Champion Costa Rica 2018

Ed_K

 Ok splain this to me, if you hit a rock and when you get the teeth sharpened enough to cut again and you look down the bar from the power head and all the teeth on the left side are a 1/32 shorter, won't the cut into a log curve to the right? Or is the chain really cutting crooked or is the bar not level 90° to the side of the bar?
Ed K

beav

Also when you file a chain way down the cut width decreases so theoretically it should cut a little faster as the saw is cutting a narrower kerf

Skeans1

Brand new off the roll chain is slow the first thing I'll do is grind the cutters to more acceptable angles and drop the depth gauges. As the teeth get shorter the depth gauges have to get shorter but one thing that's overlooked is the gullet of the cutter as well it has to be cleaned out to allow full cutter engagement.

 

 

This last one on the saw bar you can see how much the tooth has been ground vs the depth gauges, personally I like a very aggressive self feeding chain I don't want to have to work any harder then I need to well falling timber.

mike_belben

When youre getting down near the nubbins just knock the rakers down low (i tap them with a grinder) and call it your dirt chain. Hang in on a nail for that blowdown stump in the dirt problem.


Next time you put on a new chain, tighten it up and lay a straight edge over the points on two lefts or two rights, (but not both) then you can use a feeler gauge to see how many thousandths below the cutter point that raker top is. Lets call that raker clearance.  As your tooth gets shorter your raker clearance needs to grow larger to maintain the original skateboard wheelie angle.  So to just say "lower your rakers" or "maintain that clearance mike just made up" isnt enough.  Its not 1:1 with the cutter height, the ratio becomes greater than that as the cutter shrinks.  The cutter point doesnt just get lower, it also moves back away from the raker so geometry is changing with wear. If you had .040" new you might need .070 or .090 by the end.  Just making up numbers there for illustration.  I dont remember the gap size anymore, i just sharpen by hand and eyeball to make a mean corner point and throw a large chip. Good enough for me.


Also your raker needs a rounded nose to glide across wood.  Just wacking it down square with a flat file will have the corner of that square scoring wood and messing up the cutter's behavior.
Praise The Lord

mike_belben

Praise The Lord

ehp

as the tooth is filed back the number of thousands you set the racker at increases , .030 on a new chain for racker height is not the same as .030 racker height on a chain thats pretty well worn out , as the tooth sets back to cut the greater the distance between the tooth and racker changes the racker height and on how the tooth feeds into the wood , another thing is the more you file the tooth back the lower the tooth becomes and the lower the tooth causes the amount of chip wood it can put below the tooth to change , lower the tooth the smaller amount of wood chip can be held .  If you make the rackers to low on a chain it will cut smaller wood better than big wood as once the tooth channel is full the tooth just skips along until it can clear the wood under the tooth , Also the type of wood your cutting has the biggest effect on how the chain cuts 

kantuckid

I can file a chain to cut well but I still grind them after a bunch of filings and rock or soil encounters. That said I am a long ways from suggesting that i can file one to cut better than a new chain. As for narrower='s faster, hp & all the other chain stuff enters into that reality. My MS241 is a small pro saw with a narrow kerf and reality says that such narrow kerfs as for less power but to maintain the reality over many cuts is tough to do vs. a true larger saw chain as a FT logger uses. With the little skinny ones everything has to be damned near spot on to cut fast!
Kan=Kansas;tuck=Kentucky;kid=what I'm not

John Mc

Quote from: Ed_K on September 24, 2021, 08:56:53 AM
Ok splain this to me, if you hit a rock and when you get the teeth sharpened enough to cut again and you look down the bar from the power head and all the teeth on the left side are a 1/32 shorter, won't the cut into a log curve to the right? Or is the chain really cutting crooked or is the bar not level 90° to the side of the bar?
It depends on how you are setting the raker heights. If you are using a raker guide or method that measures the height by measuring down from two or more adjacent teeth, you do need to have the teeth more or less the same length for best performance. This is because the raker height is set in relationship to two teeth, rather than customized specifically for the tooth that follows it. A depth gauge tool that looks like the following, (similar to checking heights by laying a straight edge across multiple teeth) does depend in having the teeth the same length - which due to the fac tthat the teeth are sloped means the same height. Otherwise, if the teeth on one side are shorter than the teeth on the other, one side will have its rakers to low and the other too high in comparison to that raker's associated tooth, and the other side will have them too high.

A progressive raker gauge avoids that problem by customizing the raker solely to its associated tooth. The tool rests on the top of the tooth and angles down over the raker with the end resting on the body of the chain, rather than on top of the next tooth. This method of setting the raker height is far less susceptible to problems with teeth of unequal length.

When using a progressive type gauge, I still make an effort to keep teeth in the ballpark for length, but if I damage one side on a rock, I don't have to take every tooth down to the same size in order to have the chain cut straight.
If the only tool you have is a hammer, you tend to see every problem as a nail.   - Abraham Maslow

Old Greenhorn

Well written John and exactly what I was thinking of when this was mentioned previously but I didn't have time to respond at that time and forgot later on. I use that exact tool for mine (except mine is for .325 and that one shown is for .375 as I use on my 372). The only other part of this is that as the chain progresses through a cut if one tooth is long, and therefore a little high, and the next tooth is short and therefore a little low, that low tooth may not even take a cut or hit the wood. SO there is that. But in reality that chain is moving pretty fast and and we are talking about very small differences in height here. No I haven't measured it, that would be very tricky but I would guess it is around .002-.005".
 Rain day tomorrow, so maybe I will mess with this just for my own education.
Tom Lindtveit, Woodsman Forest Products
Oscar 328 Band Mill, Husky 350, 450, 562, & 372 (Clone), Mule 3010, and too many hand tools. :) Retired and trying to make a living to stay that way. NYLT Certified.
OK, maybe I'm the woodcutter now.
I work with wood, There is a rumor I might be a woodworker.

jimbarry

Some great info been posted. I just got some sample chains and bars to try out. A booklet came with it, two pages below. The image of the chain rocking up to make the cut and engaging the raker may aid in a visual to the excellent text written so far.



 


 

HemlockKing

I wasn't even originally gonna post this thread but really glad I did now. Been lots of good information, hopefully it can help future folks understand too if they come across this thread from a google search. 
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Dom

Great info. I don't use my saw often, but try to read on how to sharpen. I used to think I was good until I met a retired logger in Clare Nova Scotia that sharpened my saw. When we tested it he warned me that it would pull. Yup, nearly pulled the saw out of my hands.  :D  

When I get home I'll see if I can put to use some of the knowledge shared in this post.

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