Is a bur actually needed?

[FortyTwoBlades]

He rubbed a 200 grit on a really hard stone that didnt cut cause it was so hard and clogged. It was like using a really hard 200 grit stone and made it cut much faster

It's to get the hard stone to shed the dulled surface grit. Really hard stones won't shed their grit under normal pressure as the grit wears down and starts burnishing instead of cutting. Dressing it with another stone of appropriate grade can get a fresh surface on it so it cuts properly again.

 

[FK]

I have some old Arkansas stones that need this treatment often.

A few swipes with a diamond DMT plate will refresh the surface, especially on hard and black hard.

Regards,
FK

 

[HeavyHanded]

I have a couple of Arkansas stones I use as a lapping bed when I need to refresh an India or silicon carbide stone. 80 grit SiC powder and some oil or water with a blob of dishsoap, then lap until the grains are pulverized into a very fine mud. Keeps both stones in good shape.

On my Spyderco fine I laid in fine parallel scratches lengthwise, one side with a 320 grit diamond disk and the other I brought up to a 1200. The more shallow you run the rake path, the finer the scratch pattern gets, similar to a file.

 

[Sergeua]

I take paper towel and pull the blade on it and can hear the side that has a burr before you start seeing it. 10x magnification sux. Get 30. Even with magnification you will hurt your eyes trying to look for a burr, it's more for just checking how the primary bevel is doing.

 

[asterik216]

I have lapped countless surface plates and machine tables. It is possible I might have some diamond dust all still somewhere. It is doubtful though. It would be nice to have but I haven't repaired and calibrated qc stuff in over 10 years.

 

[FK]

I suggested 10x for easy availability, in hand held the 20x-30x has a very small field of view and lower quality optics.
Tried a few higher powered with battery powered LED lights and they are a struggle.

In my shop I have two Nikon microscopes with 10x, 15x and 20x eyepiece pairs that allow continuous variable magnification from 5x through 80x and it does open up what is happening on the apex as you progress with sharpening.

Regards,
FK

 

[DeadboxHero]

Make a burr and flatten your stones

If you're just honing, don't make a burr.

Make the burr small that's the key.
Also deburr properly, don't use mirco bevels since they make the Apex radius thicker.

But if your pressed for time and in the weeds micro bevel away. Just zero it out when you get a chance.

 

[bucketstove]

Hi,
If you quote/link the stuff you're asking about it leads to a less vague and more specific discussion
I don't like to take notes when watching videos I like when the author does it
So I like this playlist
CliffStamp "Sharpening" Playlist #1 Basic three step knife sharpening : destress the edge + shaping + finishing the apex



For extreme burr example raised with 36 grit
here is what the apex looks like

And here it by more carefully trying to avoid raising a large burr by monitoring sharpening progress by reflection and using light force

And here is after the stone is heavily worn and its cutting very very slow.

The very cutting edge, the apex on a knife is about 1 micron wide,
its like a 1 micron wire ,
its very easy to bend as its so tiny
1 micron is 1/1000th of a millimeter,
printer paper is 100 micron thick,
average beard hair is a little thicker around 120
And just like a paper clip, or a coat hanger,
bending damages the wire and the damage goes deeper than the point of the bend ,
and it can produce spectacular results
as can be seen in this video Issues sharpening a heavily abused knife - Yanagi-ba - Cliff Stamp whose thread has pics


Here is what happens with edge retention if you don't cut the edge off,
Influence of burnishing on edge retention
with each subsequent unrolling/straightening/realignment/bendingback
the edge lasts less and less and less .. measurably so

And this is very quick and easy to test yourself,
get a big piece of cardboard box and 2-4inch knife,
sharpen it up as sharp as you can so as long it shaves arm hair
then slow slice thin slices from the edge of the box, do a few slices, check on your arm if it still shaves,
when it stops shaving or its getting real painful to shave ,
feel the edge with your finger/thumb,
it will feel very very rough , much rougher than , usually more rough on one side than another,
what has happened is the edge has deformed, it has rolled, it has bent, its out of alignment, its dulled

Second part of experiment is strop the edge lightly about 2-4 passes per side
on that piece of cardboard or a piece of plastic or ...
now feel the edge with your thumb , it will feel smoother than before this unrolling/realignment
now shave some arm hairs with it, it will shave as easily as it did in the beginning

Now go back to cutting cardboard and check how quickly it stops shaving,
count the amount of cuts or the length of counts,
it will happen sooner and sooner,
until you have to strop/unroll/realign before/after each cut into cardboard

This is commonly reported on kitchen/chef forums,
chefs can keep this up for up to 6 months , using a chef/butchers/sharpening steel
to unroll/align edge, but then it doesn't work anymore
and they have to remove the damage and sharpen the knife
and this is with western style chef knives with the "low" hardness
and with good technique (ultra light stropping/alignment)

With harder steels, this bending/unrolling/alignment will eventually cause chipping of the edge even with good technique, but with bad technique, uh oh


About wasting steel , should you cut off apex/destress before sharpening ? It depends on what you want, knives last a long time
If you raise a burr on purpose you'll remove more steel, for me, ~100 sharpenings about ~5mm of blade width removed ... in my kitchen use that is sharpen every 3 months (or longer with unrolling/realignment), or 25 years of use, with another ~2cm blade width left.

In Sharpening and Knife Lifetime me2 says: With care and practice (both very important), I can sharpen the knife in question, including destressing the edge, and remove as little as 0.0005" of width per sharpening (0.0127mm or 12.7 microns). This is with forming a detectable, but small, burr. That translates to 0.05" lost over 100 sharpenings (1.27mm/300). That translates to 0.15 inches lost over 300 sharpenings (3.81mm/300). If sharpened monthly, that is 25 years.
Cliff says: ideally ~1.5mm / 100 sharpenings, or 15microns per sharpening

There is always room for improvement, just keep it fun

 

[Thomas Linton]

Butchers and professional woodcarvers - no burrs and no Scandi. Free-hand sharpening produces convex secondary bevel.

 

[asterik216]

You should say a micron is 40 millionth of a inch. That sound smaller and way more extreme. I used to calibrate CMM machine. Those are what actually measure in microns and what all other measurements are based off of.

 

[asterik216]

Hi,
If you quote/link the stuff you're asking about it leads to a less vague and more specific discussion
I don't like to take notes when watching videos I like when the author does it
So I like this playlist
CliffStamp "Sharpening" Playlist #1 Basic three step knife sharpening : destress the edge + shaping + finishing the apex



For extreme burr example raised with 36 grit
here is what the apex looks like

And here it by more carefully trying to avoid raising a large burr by monitoring sharpening progress by reflection and using light force

And here is after the stone is heavily worn and its cutting very very slow.

The very cutting edge, the apex on a knife is about 1 micron wide,
its like a 1 micron wire ,
its very easy to bend as its so tiny
1 micron is 1/1000th of a millimeter,
printer paper is 100 micron thick,
average beard hair is a little thicker around 120
And just like a paper clip, or a coat hanger,
bending damages the wire and the damage goes deeper than the point of the bend ,
and it can produce spectacular results
as can be seen in this video Issues sharpening a heavily abused knife - Yanagi-ba - Cliff Stamp whose thread has pics


Here is what happens with edge retention if you don't cut the edge off,
Influence of burnishing on edge retention
with each subsequent unrolling/straightening/realignment/bendingback
the edge lasts less and less and less .. measurably so

And this is very quick and easy to test yourself,
get a big piece of cardboard box and 2-4inch knife,
sharpen it up as sharp as you can so as long it shaves arm hair
then slow slice thin slices from the edge of the box, do a few slices, check on your arm if it still shaves,
when it stops shaving or its getting real painful to shave ,
feel the edge with your finger/thumb,
it will feel very very rough , much rougher than , usually more rough on one side than another,
what has happened is the edge has deformed, it has rolled, it has bent, its out of alignment, its dulled

Second part of experiment is strop the edge lightly about 2-4 passes per side
on that piece of cardboard or a piece of plastic or ...
now feel the edge with your thumb , it will feel smoother than before this unrolling/realignment
now shave some arm hairs with it, it will shave as easily as it did in the beginning

Now go back to cutting cardboard and check how quickly it stops shaving,
count the amount of cuts or the length of counts,
it will happen sooner and sooner,
until you have to strop/unroll/realign before/after each cut into cardboard

This is commonly reported on kitchen/chef forums,
chefs can keep this up for up to 6 months , using a chef/butchers/sharpening steel
to unroll/align edge, but then it doesn't work anymore
and they have to remove the damage and sharpen the knife
and this is with western style chef knives with the "low" hardness
and with good technique (ultra light stropping/alignment)

With harder steels, this bending/unrolling/alignment will eventually cause chipping of the edge even with good technique, but with bad technique, uh oh


About wasting steel , should you cut off apex/destress before sharpening ? It depends on what you want, knives last a long time
If you raise a burr on purpose you'll remove more steel, for me, ~100 sharpenings about ~5mm of blade width removed ... in my kitchen use that is sharpen every 3 months (or longer with unrolling/realignment), or 25 years of use, with another ~2cm blade width left.

In Sharpening and Knife Lifetime me2 says: With care and practice (both very important), I can sharpen the knife in question, including destressing the edge, and remove as little as 0.0005" of width per sharpening (0.0127mm or 12.7 microns). This is with forming a detectable, but small, burr. That translates to 0.05" lost over 100 sharpenings (1.27mm/300). That translates to 0.15 inches lost over 300 sharpenings (3.81mm/300). If sharpened monthly, that is 25 years.
Cliff says: ideally ~1.5mm / 100 sharpenings, or 15microns per sharpening

There is always room for improvement, just keep it fun

So you go by what cliff says about a bur and edge retention? I said I can see how it easily makes sense to me. Other disagreed and everyone knows way more then I do about sharpening.

On a side note he is always holding the stone in one hand and sharpening super fast. So just playing around I sharpened lime that holding a 4" stone and it is maybe easier. I can get it to shaving sharp evenly along the edge like nothing. In think it's because I can also turn the stone so I always hit the apex "mostly" and can easily follow the curve. I probably wouldn't finish like that though.

 

[bucketstove]

So you go by what cliff says about a bur and edge retention? I said I can see how it easily makes sense to me. Other disagreed and everyone knows way more then I do about sharpening.

On a side note he is always holding the stone in one hand and sharpening super fast. So just playing around I sharpened lime that holding a 4" stone and it is maybe easier. I can get it to shaving sharp evenly along the edge like nothing. In think it's because I can also turn the stone so I always hit the apex "mostly" and can easily follow the curve. I probably wouldn't finish like that though.

Hi,

Do you have a paperclip or a small bit of wire?
When you bend it one way then another and keep bending does it get weaker and then break?
Like I saysed
get bent knives edges edge apexes do, there is no try
get bent edge apexes do, there is no try
Yoda , a tester , repeating is

And if you try to bend a ceramic knife it breaks/chips?
Quote myself again I will

The explanation is metal fatigue,
like bending a wire or paper clip back and forth,
at first its hard to bend past the yield point
but it gets easier and easier ,
wire turns floppy like rope,
wire turns into rope,
and then the wire breaks



So thats where the conclusion comes from,
from basic engineering principles,
easily confirmed with a paper clip

Also important to note is
the damage extends beyond/below the bend point,
the metal is being cold worked
and it can produce spectacular results
as can be seen in this video Issues sharpening a heavily abused knife - Yanagi-ba - Cliff Stamp whose thread has pics


So,
yes I go by what cliff says
because thats what happens,
thats whats predicted to happen,
thats what they teach in school ,
knives aren't magically different than other pieces of metal,
its how things work,
thats what others have confirmed through testing,
and even I've tested it enough using to convince myself of the truth of this truth



For my kitchen knives,
my one dollar paring,
and my western style stainless $15+ santoku mini/large chef knives,
I realign/unroll/bendback when it annoys me
I can't cut bread or slice open a bag without poking it with the tip
cause they're usually used on plates within 15min of sharpening
Once or four times a year I sharpen them

Most of my ceramic knives were broken after being chipped on ceramic plates -- they just don't bend
I dont try to sharpen the remaining ones my diamond grits are low ATM

All my knives I used to remove apex from, and then proceed to raise burrs. That was 2015/2016
I've stopped doing that on sharpening stones and just raise burrs, but increasingly tiny tiny burs

I mostly cut remove apex on "project"/rehab/regrind knives I practice with, but I've been scaling that back as well. I spend more time grinding than I do cutting.
I too use stone in hand for sharpening its very comfortable "one handed" ... scrubbing stroke is the fastest stroke ... and when there is more metal to remove, when more control/precision is required, I put stone on bench and go two handed

 

[HeavyHanded]

Keep in mind relative to the discussion - not all burr formation is indicative of the edge being swayed back and forth. The burr is dud metal the abrasive failed to cleanly remove as it passed off/over the edge. If you press harder the edge will sway, and instead of the burr being simply determined by the size of your abrasive penetration it will be much larger due to the edge deforming away from the source of pressure. If you press hard the burr gets huge - where did all that steel come from? If the burr is actually curling away this is exactly what is happening - part of the edge is being rolled up into the burr.

The smaller abrasive size-determined burr forms outside the geometry of the edge and can be removed right to its attachment point. The only thing swaying is the burr. To remove it one would theoretically have to go past that point by a small margin and this is in fact what likely happens if the burr is no longer detectable, but that level of precision is within the range anyone is liable to hit using a plateau method as well.

Again, I am not aware of any conclusive testing that shows a difference one way or the other aside from CS, and while I haven't studied his methodology much, it was likely all with edges he prepared. In my own use I've seen no difference. Geometry, steel composition, HT, depending on what is being cut and how, the edge finish, all play a much larger role in retention.

 

[scott.livesey]

Part of Dr. Stamp's(PhD in physics, teaches at local college) message is train yourself to hold the blade at the proper angle and move it over the the stone. once your body knows how to do this, you can sharpen most anywhere. I usually sharpen while watching the TV. another part of Dr. Stamp's message is that all stones eventually clog and wear unevenly. use plenty of water or oil to keep the stone from clogging. he recommends reconditioning/flattening using very coarse silicon carbide(40 grit used for lapidary tumbling) and oil or water on a flat piece of steel or plate glass. you can see how the stone is wearing as you go. clean well when done and it is like using a new stone.
If you sharpie mark your edge before starting, you can avoid a burr because you can see where you have sharpened. once you have an edge you are happy with, establish a sharpness test or two, say easily pull cut and push cut newsprint. I stop sharpening once the push cut newsprint is reached. when it won't pull cut newsprint, it is time for a touch up. usually 4 or 5 strokes per side to set the micro-bevel.
for further reading and information try http://www.cliffstamp.com/knives/reviews/reviews.html.

 

[Obsessed with Edges]

So you go by what cliff says about a bur and edge retention? I said I can see how it easily makes sense to me. Other disagreed and everyone knows way more then I do about sharpening.

On a side note he is always holding the stone in one hand and sharpening super fast. So just playing around I sharpened lime that holding a 4" stone and it is maybe easier. I can get it to shaving sharp evenly along the edge like nothing. In think it's because I can also turn the stone so I always hit the apex "mostly" and can easily follow the curve. I probably wouldn't finish like that though.

That's telling you something important. Don't hesitate to finish just like that. It works, and the results you see don't lie.

For me personally, even if I use a bench stone on the bench to do most of the grinding and intermediate refinement, I ALWAYS do the last few finishing strokes with a stone in one hand, blade in the other. Sometimes it's the same bench stone, and sometimes a smaller one, dependant on the ease of holding the stone with enough control. I do this, in part, because it more intuitively facilitates adjusting the stone's angle and approach to the apex, and the pressure used as well. You have twice as many fingers feeling the feedback, both from the stone's side and from the blade's side of the operation. In particular, the lighter touch afforded by doing so, and the quicker, more intuitive on-the-fly adjustments to angle based on what you feel via both hands, are exactly the things that work to reduce and eliminate the burr.

I'm completely convinced now, that a lot of the overly complicated advice given about the mechanics of the burr's formation and subsequent reduction and removal is completely unnecessary, once one figures out the advantages of simply relying on both hands for feedback, and utilizing the lighter and much quicker-responding touch afforded by trusting what both of your hands are telling you, if you pay attention to it. All of the discussion about the steel type and physics/scientific aspects are interesting to some degree, but also essentially moot, if you just let your hands guide you based on the feedback felt through the fingertips. And the more you rely on both hands in this manner, the more you'll also begin to benefit from it while still working with the stone on a bench. Your hands will learn this stuff, if you don't allow your brain get too much in the way.


David

 

[HeavyHanded]

All of the discussion about the steel type and physics/scientific aspects are interesting to some degree, but also essentially moot, if you just let your hands guide you based on the feedback felt through the fingertips. And the more you rely on both hands in this manner, the more you'll also begin to benefit from it while still working with the stone on a bench. Your hands will learn this stuff, if you don't allow your brain get too much in the way.
David

David, I feel exactly that way but about the two handed "Japanese" method. By keeping my fingertips right on top of where I'm grinding I get fantastic feedback right where the steel is contacting.

On larger tools and field sharpening hatchets and such I will hold the stone (puck) but in that case I'm normally holding the tools steady and moving the stone. I also believe that having a smaller stone really helps with feedback in that situation.

 

[HeavyHanded]

The entire topic of burr formation, burrless sharpening, burnishing mechanisms is tough to pin down.

In my experience, using a smooth steel on low RC cutlery improves edge retention. Nothing crazy, but there is an improvement. I liken this to the small anvils used to workharden the edge of certain unhardened/partially hardened agricultural cutting tools (Fortytwo blades can elaborate on this better than me). Yes, repeated steeling will lead to brittle failure or a drawn out edge at some point, but all edges dull anyway and whatever maintenance is needed after the initial cycle, it doesn't matter if you continue steeling or take it to a mug or stone - the edge became dull from use.

Part of an experiment I ran on higher RC sporting cutlery (58-60), coming off of the initial bevel setting I smooth steeled the edge with upwards of 3-4 lbs of pressure at the exact same working angle, using a 1/4" hardened rod. In some cases this drew out the edge a small amount, in many cases it didn't. The edge was then finished with either a microbevel or at the original angle with a finer stone. If the edge had experienced a pressure burr from the steeling, this was removed with the higher angle and edge re-established at the target angle.

These were compared against edges that did not have this pre-treatment. The hypothesis was twofold - either the edge will fail early due to subsurface plastic deformation, or it will last longer due to the effect of workhardening increasing tensile strength and hardness.

There was no appreciable difference between the four preparations.

I have likewise run tests using plateau sharpening vs edges crafted with a small burr. Again, there was no appreciable difference.

Theoretically, any workhardening from flipping the burr should actually be beneficial - increase tensile and hardness trade off for decrease in ductility. This is the exact strategy employed in many laminated steels, tho arrived at using different process - the cutting edge doesn't need to be ductile. Take a piece of 3/4" copper tubing and bend it 30-40°. Now bend it back. Repeat. You'll find it gets extremely tough, tougher than you might have imagined if you've never actually done this before. Which would you rather make a cutting tool from, the workhardened piece or the original highly ductile piece? I realize this is not the same as a knife edge, but then neither is the paperclip analogy.

Ultimately, I came to the conclusion that whatever effect this factor contributes, it is absolutely dwarfed by other contributors. Tracking this down would require a huge sample from many different participants. When one person is prepping and testing for all we know the only thing we've learned is that they're better at one form of edge finishing than another.

 

[cbwx34]

Hi,



Do you have a paperclip or a small bit of wire?

When you bend it one way then another and keep bending does it get weaker and then break?

Like I saysed

get bent knives edges edge apexes do, there is no try

get bent edge apexes do, there is no try



Yoda , a tester , repeating is



And if you try to bend a ceramic knife it breaks/chips?

Quote myself again I will



The explanation is metal fatigue,

like bending a wire or paper clip back and forth,

at first its hard to bend past the yield point

but it gets easier and easier ,

wire turns floppy like rope,

wire turns into rope,

and then the wire breaks







So thats where the conclusion comes from,

from basic engineering principles,

easily confirmed with a paper clip



Also important to note is

the damage extends beyond/below the bend point,

the metal is being cold worked

and it can produce spectacular results



as can be seen in this video Issues sharpening a heavily abused knife - Yanagi-ba - Cliff Stamp whose thread has pics





So,

yes I go by what cliff says

because thats what happens,

thats whats predicted to happen,

thats what they teach in school ,

knives aren't magically different than other pieces of metal,

its how things work,

thats what others have confirmed through testing,

and even I've tested it enough using to convince myself of the truth of this truth









For my kitchen knives,

my one dollar paring,

and my western style stainless $15+ santoku mini/large chef knives,

I realign/unroll/bendback when it annoys me

I can't cut bread or slice open a bag without poking it with the tip

cause they're usually used on plates within 15min of sharpening

Once or four times a year I sharpen them



Most of my ceramic knives were broken after being chipped on ceramic plates -- they just don't bend

I dont try to sharpen the remaining ones my diamond grits are low ATM



All my knives I used to remove apex from, and then proceed to raise burrs. That was 2015/2016

I've stopped doing that on sharpening stones and just raise burrs, but increasingly tiny tiny burs



I mostly cut remove apex on "project"/rehab/regrind knives I practice with, but I've been scaling that back as well. I spend more time grinding than I do cutting.

I too use stone in hand for sharpening its very comfortable "one handed" ... scrubbing stroke is the fastest stroke ... and when there is more metal to remove, when more control/precision is required, I put stone on bench and go two handed

I'm not sure I totally buy that the "paper clip bending" analogy applies to what is going on when removing a burr or wire edge. Seems like it applies more if I were bending the actual edge back and forth... not the fatigued metal in "front" of it. (Maybe grind the end of a paper clip until you get a burr... then see what happens)?

 

[Sergeua]

I been holding the rods in one hand like cliff then i got this. I get more enjoyment out of using this one. Notice how the edges are chamfered.

If you want sharp just make a nice apex. Remove that factory burnt edge they put on with a belt sander overtime with your sharpening , pick a finish you like and be happy. Pick whether you want to microbevel or not. Cliffs method involves microbevel and is easier because he already has nice edges to begin with that he set himself.
When you reprofile a new blade I wouldn't worry about raising a burr to make things nice and even. Then down the road if you want to concern yourself with his method then sure it only saves metal.

 

[asterik216]

I seem to do better I guess you might say holding the stone. It is not quite as awkward maybe to me. It is just more natural feeling holding the stone. I don't even have to think much about the angle I'm at and turning the knife and raising the handle while hitting the curve. With both hands working together I just seem to automatically do it. I haven't messed with sharpening like that with anything big. I think a 7" blade was the most but it was a very light a cheap knife. I intend to keep sharpening both ways as I see no reason not to. Like one is better than the other and this is the way it's supposed to be done. Or you will develop bad technique or habits sharpenin a different way. As long as the end result is the same it doesn't matter how you get there. It is just a other tool added to your arsenal.