How Sharp?

[stihlrookie]

You can get by without a vise. I just set the end of the bar down on a chunk of clean firewood. That will hold it in place adequately. I adjust to taste to get the height and resting angle I want. I can hit several cutters down the bar before picking up the bar tip with one hand and advancing the chain with the other.

Yes, I own a vise, I just don't bother. Learned to do it that way such a long time ago I just kept doing it, because it works out working on a stump/log/stack of chunks or off the tailgate on the truck, the two main places I sharpen.

Exactly my method I just put enough pressure on the bar with my left to have a cutter bite into some wood below and not move, works for me up to this point.

pic #39 shows alot of wear at the bottom of the chain, is your oiler working? I've got some old chains and I don't think they are that worn. You can see the rounded metal from the bar. I use a grinder and have only ground down the rakers on 1 chain just to see what difference it made. Didn't see a difference, guess I mustn't be grinding enough off the tooth.

Oiler is putting out sufficient oil, gas and bar oil levels are always just about the same when I refill or check. The pic is not the best quality and doesn't show as much detail obviously that you would see in person. What you are seeing in the pic is some oil/sawdust residue on drivers/cutters as well as some on the bar edge. The chain and the bar are both relatively new, I have cut 3 cords with that setup.

The Chain you show in the picture should cut.
Are you sure you aren't running the chain too tight?


Mike

I had an issue, I thought, with the saw when I first got it. I would set the chain tension I wanted and if I pulled the chain approximately 3" it would either be a bit slack or end up even tighter. I went round and round with Stihl about this but was told nothing was wrong and to keep the chain nice and tight, tighter than I had been. It pulls around freely by hand and I don't have any sag at the bottom, correct tension as far as I was told by a number of Stihl techs. I can usually tell when a chain is too tight when the saw is pulling it around, mine sounds as it should.

I spent the afternoon again working in my little shop/storage building. Almost finished my bench and working on some shelves.

 

[Terry Syd]

I've been thinking about side plate angles on the cutters and how much angle they need. When I look at a square ground chain I see the side plate angle is nearly vertical. Since square ground is a fast cutting chain, I wonder if the side plate angle has a lot to do with it.

I'm wondering if the more vertical angle allows the cutter to break the strong wood fibre sooner when cutting cross-cut. Once the wood grain has been severed, the cutter can more easily take out a chip.

Has anyone experimented with different side angles on the cutter?

 

[indiansprings]

I can't sharpen worth a sheet without a vice, even have a 2" receiver welded flush with the top of the trucks flatbed, a 20.00 5 inch lowes vice on a piece of 2" square stock where I can put it on the truck or take it off if it will be in the way, works perfect, right at standing height. In the shop I use one of them magnifying glass lamps, where you can really see what you are doing, at 50 and on a ton of predisone I don't focus as sharp as I use to. I use my saws enough to wear the paint off of them, even the Stihl ES's in a month or less so I don't have a second thought about clamping them in a vice.
I tried to teach many people to hand file, almost without exception none pick it up the first few times it takes practice, practice and more practice, they one day they magically get it right and from then on they have it down once they ot the magic touch. I'd like to learn how to file a good race chain.

 

[mtngun]

Has anyone experimented with different side angles on the cutter?

Yep. 50/25/0 cuts great on softwood. 40/5/0 is great for ripping.

The more aggressive angle takes bigger bites, but gets dull easier.

 

[David (saltas)]

Terry some simple maths for you

I've been thinking about side plate angles on the cutters and how much angle they need. When I look at a square ground chain I see the side plate angle is nearly vertical. Since square ground is a fast cutting chain, I wonder if the side plate angle has a lot to do with it.

I'm wondering if the more vertical angle allows the cutter to break the strong wood fibre sooner when cutting cross-cut. Once the wood grain has been severed, the cutter can more easily take out a chip.

Has anyone experimented with different side angles on the cutter?

Terry it is simple trigonometry, you are right. I'm not sure if you are used to the per unit value idea, engineers use it all the time to do the complicated maths example fault current calculations, this is done so you can state a per unit value for the type of fault and you just multiply this by the size of the transformer blah,blah.

anyhow if we say a saw has a per unit value of one applied to each side cutter in the wood when sin of 90deg = one

if the cutter is at 80 deg then the cutter side lenght x Sin of 80 =1
=> cutter side lenght = 1/ sin 80=1.015

this means that the force applied to shearing the wood fibers by the side of the cutter has been reduced to 1/1.015= 98.5% of what it was before.

the per unit value eliminates the need to know the hp of the saw the lenght of the cutter the type of wood size or any other factor and gives you an answer for the factor you are considering in isolation.

Later you can use all of your per unit values for all of the changes you are considering.
This helps you evaluate the cost effectiveness of each element in a change to a system..blah blah blah

 

[Terry Syd]

OK guys, I'm not getting something, I'm still trying to figure out that vertical angle on the side plate. Perhaps my definitions are different from yours and we are talking at cross purposes. My definition of cutting the grains of the wood goes like this - for 'noodling' we are cutting with the grain; for 'cross-cut we are cutting across the grain, but alternating between the grains and the growth wood between the grains; for 'ripping' we are cutting across the ends of the grains.

So using that definition, Mtngun uses a lesser angle for ripping. - I see from the grinding charts that the angles are computed from the horizonal to vertical axis. In which case, the 40 degree angle is a sharper angle than the 50. To my mind the ripping action takes a greater toll on the edge of the cutter. It would follow that the ripping chain should have less of an angle in order to last longer. Perhaps the angle should be measured from the vertical to the horizonal.

Saltas, you've identified my point of interest in the angle of the OUTSIDE of the side plate. That is, the angle of the outside of the side plate relative to the horizonal. Here's where I come unstuck, on a round filed cutter the file cuts a curvature in the outside of the side plate. That curvature is initially, at the point, a steeper angle of attack into the wood than the near vertical side plate angle of the square ground chain.

Using Saltas 'fault current calculation' analogy, a square ground chain should cut faster with a vertical side plate angle of say 45 degrees - 1/sin 45. Likewise, it would also cut faster if the INSIDE of the side plate had the angle reduced from say 60 degrees to 50 degrees. (it would be interesting to see the difference in cutting ability between those two angles and which one deserves more attention)

I can understand that the square ground chain probably cuts faster primarily because of the reduced material in the corner of the cutter, but that does not explain why racers don't finish off the vertical angle with something like a diamond stone on the inside to put a curve on that vertical angle.

I'm wondering if there might also be some dynamic issue related to 'impact' on the grain of the wood rather than 'cutting' of the grain. Perhaps some wood grains part easier if instead of slowly cutting into the grain, the grain is hit with with a higher angle to help fracture it ??

Caveat: When looking at the vertical side plate angle, it should be remembered that when the cutter digs in and rocks back to the position allowed by the raker, that the 'cutting angle' will reduce the vertical side plate angle - in other words, a 5 degree cutting angle would increase the 80 degree vertical side plate angle to 85 degrees.

 

[Terry Syd]

Another observation. I suspect that when we are sharpening the top plate angle what we are really doing is sharpening the INSIDE angle of the side plate. In other words, when we put a 25 degree top plate angle on the cutter, we are also putting a 65 degree angle on the inside side plate angle. If we go to a 35 degree top plate angle, we are putting a 55 degree angle on the inside side plate angle.

I can't recall ever seeing 'glint' on my side plate cutting edge.

Perhaps if we want to 'improve' (sounds like my cartridge reloading days) the cutting ability of the cutter, a sharper inside side plate angle could improve the cutting ability. Maybe the use of a square file to reduce the angle slightly, without weakening the point, would improve the cutting so that both the top plate and side plate developed 'glint' at a more uniform rate.

 

[django]

I can't sharpen worth a sheet without a vice, even have a 2" receiver welded flush with the top of the trucks flatbed, a 20.00 5 inch lowes vice on a piece of 2" square stock where I can put it on the truck or take it off if it will be in the way, works perfect, right at standing height. In the shop I use one of them magnifying glass lamps, where you can really see what you are doing, at 50 and on a ton of predisone I don't focus as sharp as I use to. I use my saws enough to wear the paint off of them, even the Stihl ES's in a month or less so I don't have a second thought about clamping them in a vice.
I tried to teach many people to hand file, almost without exception none pick it up the first few times it takes practice, practice and more practice, they one day they magically get it right and from then on they have it down once they ot the magic touch. I'd like to learn how to file a good race chain.

Wow. Could have wrote that myself minus the Prednisone and the desire to file a race chain. I'd get done with the race chain and never use it because I had 5 hours in sharpening it!

With respect to the many paragraphs previously posted attempting to delve into the minutia of chain sharpening: I like a good "caveat" as much as the next guy

It is a fascinating subject, however, I believe for the singular purpose of the tool, we are applying a degree of precision not necessary or beneficial to the general task the tool is required to perform, when that task is to put wood in the truck. All different types of wood. In all types of weather.
In my experience, applying 200% of the appropriate time required to complete any task to achieve a 2% increase in "performance" is an exercise in diminishing returns unless you're in competition or a "chain geek". (I just made that term up. copyright Django 2011)

We can tie ourselves in knots over all of the geometry involved, and materials, and environmental conditions and media being processed, horsepower, torque, state of tune, fuel being used, 2 cycle oil, bar oil, bar type, chain pitch, chain configuration, etc...etc...All of this comes into play when you get down to what the "chain does".

It's all academic and tedious for the most part, and an exercise in futility, especially if all you want to know is the basic technique of sharpening your chain with a file so you can just go cut some wood. That is enough by itself.

Look at a brand new chain. Try to make your sharpened chain look like that. Simple.

I feel better now.

 

[J.W Younger]

Another observation. I suspect that when we are sharpening the top plate angle what we are really doing is sharpening the INSIDE angle of the side plate. In other words, when we put a 25 degree top plate angle on the cutter, we are also putting a 65 degree angle on the inside side plate angle. If we go to a 35 degree top plate angle, we are putting a 55 degree angle on the inside side plate angle.

I can't recall ever seeing 'glint' on my side plate cutting edge.

Perhaps if we want to 'improve' (sounds like my cartridge reloading days) the cutting ability of the cutter, a sharper inside side plate angle could improve the cutting ability. Maybe the use of a square file to reduce the angle slightly, without weakening the point, would improve the cutting so that both the top plate and side plate developed 'glint' at a more uniform rate.

You ever use a goofy?

 

[Terry Syd]

Nope never used a goofy file. Perhaps with a semi chisel chain a smaller round file would work well on the inside of the cutter.

I'm not looking to make a race chain (not yet anyway), however if I can discover the various principles in chain sharpening, perhaps I can dress up my work chain to get better performance. There are 'little' things to learn about chains, like a progressive raker plate, that make chain maintence a lot easier and the chain more efficient.

 

[J.W Younger]

Nope never used a goofy file. Perhaps with a semi chisel chain a smaller round file would work well on the inside of the cutter.

I'm not looking to make a race chain (not yet anyway), however if I can discover the various principles in chain sharpening, perhaps I can dress up my work chain to get better performance. There are 'little' things to learn about chains, like a progressive raker plate, that make chain maintence a lot easier and the chain more efficient.

Yep, similar concept. Thing is with the goofy you can go with a lesser angle on the top plate and still get a sharp angle on the side plate. Less set in the cutter angle along with a sharper corner and side plate will cause less dive into the sides of the cut. Less wood removed, less friction etc.

 

[Terry Syd]

Can a goofy be used on semi chisel?

Edit: I've been thinking about that 'dive into the sides of the cut' and it makes a lot of sense. A lesser angle would create less resistance and create less 'dive' for a thinner kerf. Sounds like a good concept to work on.

 

[J.W Younger]

Can a goofy be used on semi chisel?

I just did but have not cut enuff to know how well it stays sharp. It does cut well even tho it definitly looks "goofy"

I'm thinkin it will not hold an edge any better than round chisel which kinda defeats the purpose. Its smoother tho.

 

[Terry Syd]

Well, there's another item I have to purchase to see if I can make another small improvement on my work chains.

 

[J.W Younger]

Well, there's another item I have to purchase to see if I can make another small improvement on my work chains.

I'll see if I can get a picture up later, having trouble locating my charge cord.

 

[Terry Syd]

Thanks, looking forward to the picture/s.

 

[Fish]

You ever use a goofy?

Once... I didn't call her that though......

 

[mtngun]

In which case, the 40 degree angle is a sharper angle than the 50. To my mind the ripping action takes a greater toll on the edge of the cutter. It would follow that the ripping chain should have less of an angle in order to last longer.

The idea is too maximize cutting speed, not maximize time between sharpenings. :smile2:

In practice, the 40 degree grind seems to last just as long in clean wood as 60 degree grind, even though theory says it shouldn't. But, it does not tolerate dirt.

Sharper angle cuts easier, faster. Axe cuts easier than splitting maul.

Ripping chain dulls on the edge of the top plate. Never see glint on the side plate.

If ripping chain is ground 0 degree top plate, glint on dull chain will be uniform across top plate, suggesting cutting action is spread evenly across top plate. Top plate is doing most of the work.

Conventional chain dulls at the corner first, suggesting corner does most of the work.

 

[Terry Syd]

The glint across the cutter on the ripping chain sounds consistent with the cutter having to cut the wood fibres, while the side plate has an easier task of cutting with the grain. For cross-cutting the side plate will spend a lot of time cutting through the fibres, however I have yet to notice any glint on the side plate. Having said that, since the glint shows up on the top of the corner first, that is what catches my eye and tells me the chain could use a touch up.

If a reduction in angle of the side plate will both reduce the friction of cutting and the dive of the cutter into the side of the kerf, I may be able to work with that concept to dress up a better working chain.

It takes a fair bit of work to get an engine to produce 10% more power, but if I could dress up a chain and get 10% faster cutting I would consider it a win - it would also be knowledge I could transfer to other saws.

One thing that occured to me during this discussion was the fact I have never eye-balled the bottom of the kerf. It may be that if I stopped the chain in the cut, backed it out and then cut away the sides, that I could look at the way the wood chips were forming. The wood might tell me what is really happening in the cut, versus my assumptions of what I think is happening.

 

[David (saltas)]

Terry I like the way you think, not always easy to get more hp from a bike with the limited things you are allowed to do.But making the bike roll easier can be cheap if we are talking a 4 lap sprint.