Buuuuuuurrrrrr!!!!

[bzzhewt]

HELP!
This question is directed to Cliff Stamp and anyone else who is advanced to expert at sharpening. Please keep in mind that i am very knowledgeable and experienced in many sharpening techniques when you answer this thread, so please, no basics.

The basic problem is this:
no matter what kind of burr removal technique i use, how fine of a stone or how many times i strop or grind, I can still ALWAYS see a very fine, almost microscopic burr on the very edge of my blade. The light needs to be just right and i have to take of my glasses and stare at it from two inches away, but it's there.
I sharpen freehand and am nearly expert at maintaining an angle, and have tried the razor edge method (dual angles), conventional coase to fine single angle method, progressing through finer stones, and i have tried various stropping methods, but that tiny wire edge STILL remains no matter WHAT I DO OR HOW LONG I DO IT!

the edge is scary sharp and lasts fairly long, with no evidence of normal sudden dullness as with wire edges, so is this tiny wire egde i'm seeing actually a normal part of the edge, like tiny teeth?
Could i possibly be progressing from too coase a grit to to fine for the last burr removal step?

In short, i am frusterated. I do everything i have possibly heard of ten times longer than i need to, but still get the burr. The methods are supposed to be quick and simple; am i missing something here?

Is that tiny wire suppposed to be there, or am i just expecting too much polish on my edge??

Pardon all my talk, but i want to be clear on my curious question. Any advice would be welcome to solve this mystery of "the burr that i can see that isn't there!"

Thanx

 

[Darkjedi2]

I completely feel your pain on this subject. I am wondering what kind of knife steel are you sharpening. I friend of mine got me a cold steel kukri made of the 1055 medium carbon steel, and I can't get rid of the burr.

I have always been able to get a razor edge but thing is bugging me.
Sorry for possibley hi-jacking your threat.

 

[HoB]

What is the grit of the finest stone that you are using? And how much pressure are you using. On a fast cutting medium stone, you can build a burr with a single stroke. It is weird though that you don't polish it off with the strop. I assume you use a stropping paste and I also assume that you are doing alternating strokes when finishing off.

When doing a micro bevel, by how much do you raise the blade? Maybe not enough. And maybe you are building too large a burr when working on your coarse stone. I believe it was Jeff Clark, who has talked about not liking to build and then chase a burr. All just guesses. Try giving us an example sharpening regime.

 

[bzzhewt]

OK
let's say i'm starting with a dull knife and going to do a complete reprofile and microbevel on a three inch aus-8 drop point folder.

i start on a norton crystalon 8 inch coarse/fine stone at about a twenty degree angle. I sweep in the classic cutting motiion with moderate pressure five to ten times a side until i there is a burr along the entire edge. Then, using preogressively ligher pressure i alternate one sweep per side to smooth out the grind marks and shrink the burr.

Then i go to the "fine" side of the stone, which by the way on a crystalon is still WAAAYY to coarse to really be considered Fine. I alternate one sweep per side with lessening pressure as before, untill the edge is as fine as it will get on this grit.

then i go to a fine DMT or India (aluminum oxide, which cuts less agressively than crystalon, which is Silicon dioxide) fine stone, and repeat the one side alternating proccess until my edge is smooth.

Here is where i will either start the new microbevel by raising the blade about five degrees and repeating the steps above, very lightly, or i will move on to a lansky dog bone (triangular cross section) and smooth out the primary edge even further. If i do a microbevel, i continue onto the dog bone using the same five degree angle increase to further polish the microbevel. (I hope that's clear, i suck at describing stuff).

from there, if i wish i will strop on a piece of quarter inch thick leather loaded with diamond dust (i think, my piece may be jeweler's rouge. i don't know what it is, but it cuts fast). sometimes i alternate sides, sometimes i do ten to twenty a side; sometimes light pressure, sometimes heavy. I have seen little difference with what stropping technique i use.

I have also tried Wayne Goddards method which progresses from a shallow, 12 to 18 degree angle on a Crystalon coarse stone straight to a "A few very light sweeps" [to paraphrase Goddard] at a Thirty degree angle on a Fine India Aluminum Oxide stone, which is supposed to take off the burr and leave a long lasting, coarser utility edge which is supposed to shave hair, but still be fairly tough. This method is quite good, but doesn't work for me the same as for Goddard.

 

[ANGRYMOB]

I am sorry if this seems simplistic as I am new, but I sharpen on a slack belt with a 400 grit belt to get the burr, flip the belt over and hit each side one time with the back of the belt, then strop on the back of a regular walmart leather belt, no polish or anything, now I just finished doing this and read your post, so to be sure, I took a photographers loupe( magnifying eye piece) and there is no burr whatsoever. Now, it is my understanding that this creates a convex edge, but it shaves with no effort, slices and chops, and the edge holds just forever ( O-1) Of course, if you dont have a belt sander, it is not much help, but alot of makers use this method and you can get a 1"X30" grinder for around $50.00

 

[Cliff Stamp]

i start on a norton crystalon 8 inch coarse/fine stone at about a twenty degree angle. I sweep in the classic cutting motiion with moderate pressure five to ten times a side until i there is a burr along the entire edge. Then, using preogressively ligher pressure i alternate one sweep per side to smooth out the grind marks and shrink the burr.

Then i go to the "fine" side of the stone, which by the way on a crystalon is still WAAAYY to coarse to really be considered Fine. I alternate one sweep per side with lessening pressure as before, untill the edge is as fine as it will get on this grit.

then i go to a fine DMT or India (aluminum oxide, which cuts less agressively than crystalon, which is Silicon dioxide) fine stone, and repeat the one side alternating proccess until my edge is smooth.

Here is where i will either start the new microbevel by raising the blade about five degrees and repeating the steps above, very lightly, or i will move on to a lansky dog bone (triangular cross section) and smooth out the primary edge even further. If i do a microbevel, i continue onto the dog bone using the same five degree angle increase to further polish the microbevel. (I hope that's clear, i suck at describing stuff).

from there, if i wish i will strop on a piece of quarter inch thick leather loaded with diamond dust (i think, my piece may be jeweler's rouge. i don't know what it is, but it cuts fast). sometimes i alternate sides, sometimes i do ten to twenty a side; sometimes light pressure, sometimes heavy. I have seen little difference with what stropping technique i use.

You create a large burr with your initial honing and never actually take steps to remove it directly. Here is what needs to be done in general :

1) create the edge with the rough stone, if the knife has been extensively used you will create a large burr because the edge will be made of weakened metal which will bend easily rather than be cleanly cut, unless the stone is also optimally fresh burrs will again rise, some steels also have a horrible set of properties for burr formation (low machinability and low hardness, many S30V blades for example)

2) remove the existing burr before continuing, this is the critical part, even at the rougher finishes the edge should be crisp and pass pretty much all sharpness tests (outside of those that require a very high polish), it should shave cleanly, slice paper well, show no glints from light etc., this is done by elevating the angle of the edge and giving it a couple of passes on a freshly cleaned hone starting with the side opposite that you just finished on previously

3) at every stage of grit, check the edge and make sure there is no burr, if it back there (it should be reduced in extent), then remove it the same way, if it is harder to remove, or is worse in extent, your edge is heavily weakened (corrosion, metal fatigue from impacts) and you should grind all of that away on your coarse hone and start over (those are the blades that are fun to sharpen)

4) do not by any means sharpen a blade to a final stage and only then try to remove a burr, this is an exercise in frustration for all but the steels which don't tend to form a burr in the first place, and don't rely on stropping or edge trailing strokes to remove a burr because these actually create burrs readily

You can make life easier for yourself by :

1) making sure your hones are clean and flat
2) doing enough work with the rough stones to get clean metal
3) using steels with a sensible combination of hardness and wear resistance

Jeff has better descriptions of the process, but the above are the basics, in shorthand form :

+remove burrs with the abrasive grit that created them
+use edge into honing at a slightly elevated angle
+check every grit increase

When all of this fails take a cheap knife and beat it with a hammer in front of your other knives to show them what will happen if they don't step into line. I learned this technique when I watched a friend of mine use it on a lock in amplifier which was refusing to co-operate, at times you have to sacrifice one for the good of the many. This is why in any engineering labs there are always a pile of broken machines which are never thrown out, they are there to make sure the good ones are reminded of what happens if they get cranky on recalibrations.

Here is a recent post from Jeff, angles of course change from knife to knife, but the basic process of honing remains the same :

http://www.bladeforums.com/forums/showpost.php?p=3152114&postcount=14

I have also tried Wayne Goddards method which progresses from a shallow, 12 to 18 degree angle on a Crystalon coarse stone straight to a "A few very light sweeps" [to paraphrase Goddard] at a Thirty degree angle on a Fine India Aluminum Oxide stone, which is supposed to take off the burr and leave a long lasting, coarser utility edge which is supposed to shave hair, but still be fairly tough.

He likely works on steels which don't tend to produce burrs, because that method is prone to form them.

-Cliff

 

[nozh2002]

I am forwarding you advice from Vadim Denisov (Norilsk):
"Just freeze it in freezer and stroke one-two times on any stone - burr will fall away".
I did not try it myself but sounds interesting.

Thanks, Vassili.

 

[jim_w]

When all of this fails take a cheap knife and beat it with a hammer in front of your other knives to show them what will happen if they don't step into line. I learned this technique when I watched a friend of mine use it on a lock in amplifier which was refusing to co-operate, at times you have to sacrifice one for the good of the many. This is why in any engineering labs there are always a pile of broken machines which are never thrown out, they are there to make sure the good ones are reminded of what happens if they get cranky on recalibrations.

You can acheive the same effect on computers using these books: http://tinyurl.com/8om5h. Just look menacingly at the computer, then open one of the books - they always fall into line.

 

[edb]

Cliff,

Re: part of your post:

"...some steels also have a horrible set of properties for burr formation (low machinability and low hardness, many S30V blades for example)..."

Do you include CPM-S30V on that list??

 

[Cliff Stamp]

Do you include CPM-S30V on that list??

It doesn't have to be, however some of them are being tempered fairly soft so you end up with an edge which rolls easily by is hard to machine. It can be left much harder which eliminates this problem.

-Cliff

 

[bzzhewt]

Thanks for your answers guys, keep em coming.
Cliff, i Know what you are saying about creating too large a burr, then not removing it, but to my knowledge i am removing it before progresssing to the next step. That is why i lessen pressure and alternate sides, and i will not go onto a finer stone until i see no burr. The only time I can't seem to take care of the burr is with the final polishing stone, the triangular dog bone thingy.
Maybe going from a DMT Fine Straight to a ceramic is too big a leap??

 

[Cliff Stamp]

That is why i lessen pressure and alternate sides ...

This doesn't tend to remove it, just refine it to a higher polish, you need to raise the angle this is essential to focus the stone on the burr and the burr alone. The burr should come off immediately as in 1-2 passes, if it doesn't you can end up with a burr which is aligned right on the edge which will act like a crisp edge until you move to a finer hone and then it reappears as soon as you hit one side again. The edge should be crisp and strong at every finish. I usually make large jumps as well, often going from 220 SiC to medium Sharpmaker ceramic to fine ceramic.

-Cliff

 

[Jeff Clark]

Don't expect to remove the burr by honing at the same angle with lighter pressure and don't expect to remove the burr by honing at a slightly higher honing angle. Don't expect to remove the burr with an extremely fine hone. What you need to do is hone at a really extremely high angle--yes you need to make your blade duller. In general you need to use something like a 45-degree angle (so that you are creating an astoundingly dull 90-degree edge angle)! You are undoing much of your sharpening effort so you want to only do a tiny amount of deburring. So you really want to use light pressure at this angle and you want to use a fine hone, but you need that hone to cut the burr off so the hone needs to be abrassive--not too smooth.

When I first finish reprofiling I have a large burr to get rid of. I like to use a very fine diamond hone for this purpose. It is pretty easy to eyeball a 45-degree angle. Use gentle edge-forwards alternate side honing strokes the minimum number to get rid of the burr. Go back to your normal fine honing techniques. When you are almost done do another pass at deburring using either diamond or a freshly cleaned fine hone. You want to finish the overall process by light honing, not by deburring. Get rid of your burrs just before your last light honing steps. The idea is to remove the traces of that 90-degree deburring step, but not remove too much material and create a new burr.

Since you seem to be familiar with freehand honing I'm giving you these tips in a generalized manner. I think that you can see where I'm going and can develope your own version of this idea.

 

[bzzhewt]

Thank you Jeff.
I'm curious, how sharp an edge does this method leave?

 

[Jeff Clark]

This is what you do if you overhone your straight razor. There is no particular limit to how sharp you can get your knife using this method. The idea is to remove all traces of your deburring so the limit to sharpness comes from your honing process.

 

[Cliff Stamp]

As a side note, Wayne Goddard has a similar approach which he has described in Knives 2002. He sharpens at low angles, 12-15 degrees, to create the primary edge profile, but burr removes at a massive 30 degrees, he also strops after removing the burr.

He doesn't recut the edge after the burr strokes, but notes that since there is a minimal amount of metal removed the reduction in cutting ability is small, plus if you strop to raise the polish this will blend the micro-bevel back into the primary edge grind.

Goddards methods is near idential to the procedure described in "The Axe Book" by Cook.

-Cliff

 

[STR]

Although really stubborn burrs are rarer for me these days I still get one now and then that drives me knuts kind of like you describe. You have had some really good info thrown at you and there isn't much that I could add to the already excellent thread here.

There is one little trick that I do that no one has mentioned though so I'll throw it out there. It is kind of along the same lines as what Jeff said where he mentioned, "you are undoing much of your sharpening effort". As he said you want to use light pressure but what I do is this.

One of the reasons besides others that I have mentioned in the past that I like using the Flex-Cut polish paste is because of the way it comes. It is a little bar that you use like a crayon on your strop. Well, I've found that for particularly stubborn burrs when the time comes to have to do the drastic extremely high angle thing to make the blade slightly duller that just a few light slices into the solid bar of polish seems to do the trick for me. It is just another way of meeting the same end. Maybe worth a try if nothing else has worked. I'm sure if you have a block of white or green for a sharpening wheel that these will work also.

I've found that if I do this just before my last steps in the honing process that it seems to work well. Just a thought. As I said the info is already here though I just have an alternate way of doing the same basic thing really.

Hope you get it licked.

 

[Nosmo]

Best thread for a long time. Ben who owns EdgePro once told me that you have to 'cut' the burr off, ( very high angle ) in essence blunting the blade, and then re sharpen stopping just before the burr re forms. Easier said than done......but I understand the principle.

 

[bzzhewt]

You guys have helped immensely, but i do need clarification on a few things.
Cliff, when you say to remove the burr at every honing step, does that include the coarsest reprofiling step, too? The way I understood you, it sounded as if even at that step, i should still be able to shave my arm and cut paper, which, in my experience, is impossible.
Also, am i to remove the burr on a finer stone than what i ground it on, or the same stone. I kinda got the idea of both...????
How high am I supposed to elevate the blade to remove the burr? Jeff, I know you said 45 degrees, but i am referring to the other methods that tend to use this step to make a microbevel of sorts instead of a blunting/burr removal step.
Thanks.

 

[Cliff Stamp]

i should still be able to shave my arm and cut paper

Yes, it is a common perspective that really coarse edges can't shave or do precision cutting, not true. In fact I have seen 100 grit AO edge shave above the skin, really acute angle though, <10 degrees .

..am i to remove the burr on a finer stone than what i ground it on, or the same stone.

I usually go finer, but I would not make huge grit jumps when doing so, a 800 grit waterstone easily cuts the burr off a 220 grit one, but I would not try a 4000 grit one to do so.

The only problem with using the same stone is that it removes metal so fast that if you use more than a few passes the finer stone has too much work to do if you want to remove the micro-bevel. So if you step down you have a little slack.

It also depends on the nature of the burr, the more presistent it is in sticking around, the more coarse you have to go to try to get rid of it.

How high am I supposed to elevate the blade to remove the burr?

The higher you go the more effective burr cutting becomes, however you will start to notice a drop in cutting ability if you use more than a couple of passes and thus actually form a microbevel at large angles which you can then cut off with finer hones and then repeat the burr removal process.

As a side note, the wider the hone you use to sharpen, and the more aggressive it is, the lower the burr tendancy. People who sharpen on large bench waterstones have no where near the problems of people who sharpen on ceramic rods.

Plus you can also reduce burr formation by changing the angle the blade makes with the hones, the most effective way is to have the honing strokes at 90 degrees to each other so have the blade at different 45 degree angles on both sides. This is kind of awkward for me to do so I only use it when an edge gets really stubborn.

-Cliff