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What do dull cutters feel like compared to sharp cutters?

Robert P

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How would you describe what a sharp vs. dull chain feels like to the touch? Does the edge of the cutter feel obviously different if you run your finger over/against it? Is there some test you use or do you go strictly by saw performance?
 

flushcut

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Delavan, WI
Sharp cutters = happiness
Dull cutters = sadness
Rakers are dependant on wood type.
The cutters feel sharp like a knife. I like to preform cataract surgery on a gnat with mine.
 

lxskllr

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A sharp cutter feels like it'll bit into your finger when you run your finger across it, but the real test for me is in wood. I use the finger test if I haven't used the saw in awhile. I typically sharpen it last thing after a session, but not always, so the finger test helps tell me where I stand.
 

Tree09

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Long time no see Robert! It's a visual thing, if you can see the edge it's dull, just like a knife. In wood if you are making dust rather than long chips it's really dull.
 

frans

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Combination of looking and touching I suppose. I generally simply rub the top to clean is so I can visually inspect. Making a slice in the tip of your finger sucks. Gets infected and drips blood all over the place.
Instead of rubbing your finger on the cutting edge, look closely at the tooth.
Is the leading edge a bright clear edge?
Look at the top flat part of the tooth. If you see worn marks extending over back towards the back of the tooth that means that the outer layer of hardened chrome is worn back from the leading edge.
This is a dull tooth.
The reason why a cutter tooth can be sharpened at all with a file is because that electroplated thin chrome layer is very hard, while the body of the tooth is soft steel. So the file bites into the 'gullet' of the tooth and leaves the chrome layer alone. That chrome layer needs to be the leading edge, or first to come in contact with the wood. The rest of the tooth, essentially, carries away the cut wood.
When filing you may see that chrome layer peel back from the leading edge. If you are paying attention. You can flick off the curled chrome with your finger. Once the chrome layer is again 'proud' to the leading edge, your tooth is sharp. ( well, that is the main thing, there are a few other factors as well)

So if your tooth shows wear on the outer layer, the tooth is dull and must be filed.

Then there is the angle(s) of the tooth, the rakers, the bar groove, the oiler, etc etc. All must work together to cut.

When filing a chain you should rotate the chain to the worse/dullest/ shortest tooth. Sharpen that tooth, then make all the others match

I have noticed that people who sharpen their own saw chain are a lot more careful with how the saw is used.
A pro sawyer is very particular how their saw is used. It's a scaple and even tho it sorta looks like miniature ditch witch, it's really not.

Round ground is more forgiving than chisel cut. We only use round ground because most of our trees are dirty back yard trees and we cut low to the stump.
Pro sawyers/ loggers usually cut higher well away from dirt.
 

SeanKroll

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Oct 13, 2016
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Olympia, WA
Use the zoom in your phone camera.

You can expand the picture in your photo gallery.

I could see the tip was still bent by the shine of the sun, with a naked eye. IMG_20200506_154238062.jpg


Compare a new chain to a dull chain to a partially sharpened to a fully sharpened chain.
This cutter is pretty close to sharp.
 

Marc-Antoine

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If the cutters are covered with crap, usually they are dull. That's because the unwanted friction heats the cutters and some debris melt/dry and stick on the metal. A sharp cutter stays clean most of the time. The dull cutter feel smooth under the finger because its edge is rounded. It catches the light and looks shiny.

By filing, you want to suppress the rounded part to come back to the straight adjacent surface. But you need to remove all of it, or the edge just slides on the fibers instead of biting them. Problem, the finger can feel an acute edge and be happy with that, even if there is still a bit of worn area. So, the finger isn't a good test. It's more accurate to try to catch a light reflect on the edge. Move around the bar to vary the angle from the light source. You see something, a tiny bright spot, file more. You can see nothing, that's good, go to the next one.
The saying "that will be good enough" doesn't work too well here.
Of course, if you have to wear prescription glasses, do it.
Be sure to use a sharp file, otherwise the burr may give you a wrong indication (plus that doesn't cut well).

If the chain hit some metal or a stone, the damages to the cutters can be massive. The edges are abraded, crushed, bent...
If they slide on a stone embedded in the stump during a few seconds, the cutter's top is heavily abraded and the loss of metal can extend way back behind the edge. If you want to save that chain, you need to remove all that damaged area. That could be so much as 1/8" to file on each tooth. A lot of file's strokes.
 
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lxskllr

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If you want to save that chain, you need to remove all that damaged area. That could be so much as 1/8" to file on each tooth. A lot of file's strokes.
If I only have a couple wrecked teeth, I treat them like the rest, and give them a few file strokes and call it good. The rest of the teeth will eventually catch up, and in the meantime, I'll have a semi skip chain. No point in removing a bunch of life for little gain.
 

Frankie

I Build and Run Ported Saws !
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Feb 28, 2019
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Buffalo NY
I call them razor-sharp if they catch my thumb-nail when lightly dragging it across ... A sharp chain and a ported saw makes for quick cut-cut . You must also set the raker height for EACH tooth the same (regardless of the tooth length) for a superior cutting experience. Stock saws 30degrees leading edge and a .026 raker is a good place to start and will give satisfactory performance on most east coast hardwood (ash , oak , hard maple) ... Ported saws have more balls and can pull a lower raker without bogging/stalling the saw
 

Bermy

Acolyte of the short bar
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Tasmania
You can have about three short cutters in a loop of chain if they are the most damaged, rather than file all of them to the shortest/most damaged...I suppose how many total depends on the length of your chain.
I used to file ALL my cutters to the length of the shortest one, don't do that any more, takes too long. Saw still cuts fine.
 

Burnham

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Robert...it's really easy. Sharp cutters feel sharp, like a well honed kitchen knife. Dull cutters feel dull, like a kitchen knife that won't slice a tomato cleanly. The former will slice your finger at the most gentle of strokes across the top angle...or passing said finger down the length of that sharp kitchen knife. The latter won't cut anything.

Even the most dull-eyed cull can see the difference, if one would prefer to not bleed from experimenting with finger flesh :).

This inquiry reminds me again how generally unsuited it would seem to be that you are to tree work. But I'll give you much credit for persevering through it all. I wish you luck...you need it, sir.
 

Robert P

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  • Thread Starter Thread Starter
  • #13
Even the most dull-eyed cull can see the difference, if one would prefer to not bleed from experimenting with finger flesh
There are degrees of tactile testing besides jamming your finger into a cutting edge.

This inquiry reminds me again how generally unsuited it would seem to be that you are to tree work. But I'll give you much credit for persevering through it all. I wish you luck...you need it, sir.
I'm curious what you think editorial commentary like this is supposed to accomplish.
 

Mick!

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I think Burnham is confusing you with another guy In fairness.

The other guy asked us how to fell a tree from pictures, then put one through an electricity supply box.

Either way, it strikes me as a silly question, does it cut wood? Then it’s sharp, there’s no way of really being sure if a chain will cut well until you put it in the wood.
 

pantheraba

More biners!!!
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near Atlanta
Great input by Frans....visual...looking for that rounded edge and that clean crisp edge makes the difference for me. I usually try to position the saw for best use of ambient reflected light. When I have directable light available I use it to shine at the edge of the cutter to get the best visual.

Good explanation by Marc Antoine about the chrome coating and where it meets the softer metal...that helped connect some dots for me.
 

Cobleskill

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Dec 31, 2006
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Western New York near Lake Ontario
I look for the file to meet the chrome. You can see metal from the file coming over the top. Rubbing thumb across like you would check a knife gives you a pretty good idea. Along with eyeballing. Watch the progress from sharp to dull and make some observations.
 

stig

Patron saint of bore-cutters
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I was fooled by that, too.
Thought ol' Robert was back trying to turn me into a christian.
 

lxskllr

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@rfwoody

edit:
and my favorite quote from you Mick...

Client: Hi Robert, I hear you do tree work, got some leaning towards our house, think you can take them out safely for us?

Robert: Sure I can, I’m fairly sure there won’t be a repeat of the power line incident, I’ll come along and take some photos.

Client: Okaaay, why do you need to take photos?

Robert: I will need to ask some guys on the internet how to do it.

Client: (turns to wife) you see honey? I told you we’d picked the right guy!

:^D

I liked Woody. He seemed to take the ribbing pretty well, and was willing to give treework a go, consequences be damned :^D
 
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stig

Patron saint of bore-cutters
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Location
Denmark
Yep, willing to put up with anything, except for non-believers.

He offered to donate money to Butch, if I would an article about christ, that he posted.

I, of course, offered to donate twice the amount, if I didn't have to read it.

Fun times.
 
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