am i doing this right

[faceplant]

Ok Im going to take a new approach and instead of asking how to sharpen a knife properly Im going to tell you what I do to sharpen a knife and pose a few questions along the way.

I start out (assuming the knife is very dull) on a 300 grit diamond sharpener and drag it across from the hilt side to the point side with the blade at about a thirty degree angle, until something changes in the way the knife feels, its like its not cutting the blade anymore, (this usually occurs between 15 and 20 strokes) then I repeat on the opposite edge of the blade

then I switch to a 700 grit and repeat the process except I do another ten strokes on each side with a lighter touch.

finally I move to a 1250 grit and repeat the process in step two.

the results I get from this is an edge that will will usually remove a few hairs but nothing like a factory edge and I can't tell whether the edge is polished or not.

the questions I have are, how do I tell whether Im getting a polished edge or not,do I need to have any higher grits to get a better edge or is it a question of my technique.

any reccomendations would be appreciated

 

[db]

First before you move on from the coarse edge you need to know if you've sharpened all the way to the edge. You can do that by sharpening until you get a burr, looking with a loop or something, coloring black with a marker and seeing if all the color is gone. Once you've ground all the way to the edge on both sides then move on to the finer grits. I think you will find even at your coarse level your knife will be very sharp.

 

[tim8557]

I think that you are on the right track, but if I understand your post, your angle is way to high. You are ending with a 60 degree inclusive angle which is too high for a knife; maybe for an axe.

Personally, I'd start at about 10 degreees to reprofile the edge and cut in a relief bevel. I'd do that until I created a burr edge. Then I would raise it to 15 to 20 degrees to cut in the cutting edge and go up the scale from there.

It is important that you reach a burr edge

 

[gunmike1]

It sounds like you are going with a VERY obtuse angle. Depending on the knife you should go maybe 15 degrees per side (or less with good steel), 20 as an absolute max. I am pretty new to sharpening, and have only used benchstones (also a bastard file) for reprofiling, and I use the sharpmaker for putting the final edge on the knife. I can't recommend the sharpmaker enough, I was putting on razor sharp edges with ease after getting it. With proper technique you should be able to put a very sharp edge using benchstones, I just haven't practiced enough to get to that point. You may want to do a few light strokes at an elevated angle to remove the burr before going to your lower grit stones. Also consider putting a microbevel for the final edge, usually at a few more degrees per side than your backbevel. These were the recommendations I got from people on this site, and they are working well for me. I'm sure the experts here will help you out with some more tips, but these were some of the keys I got when I asked some questions on this site.

 

[frugalweaver]

Get your angles right as said above. Then you might consider using a strop to polish the edge and get that final frightful sharpness

 

[faceplant]

this is a stupid question I know but I don't know what the bur is supposed to look like.

 

[Noesis]

faceplant,

I don't know if you have ever seen or played with those toys that are basically a simple face with a bunch of magnetic powder on top of it, enclosed in plastic. You move the magnetic powder around with a magnet pen to create what looks like haircuts, mustaches, etc. Anyway, if you know what i'm talking about, a very large burr looks like there is this magnetic powder all along the edge, usually straight out or curled back. I am guesing that under magnification a smaller burr would appear about the same.

 

[Cliff Stamp]

A burr will be visible readily under light as a part which will cast a shadow because as it is folded over. Expose the edge to a bright light and rotate it a little, if the light reflects from the very edge straight on then the eges have not been ground to meet yet. If as you turn the blade and you see shadows along the edge then you have a burr. If you are sharpening by altering sides then it will form partly along one side of the edge and partly on the other.

-Cliff

 

[cbwx34]

A burr will be visible readily under light as a part which will cast a shadow because as it is folded over. ... If as you turn the blade and you see shadows along the edge then you have a burr. -Cliff

Where is this coming from? A few days ago, you were posting that burrs under magnification cast a shadow, now its casting shadows readily under light?

A burr is best detected by feeling for it. You can drag your figner pads over the top from the side (not along the edge) and you'll feel it much easier than you can see it.

Under magnification, a small burr looks kinda like what Noesis described... or as little flakes of metal that extend beyond the edge. Here's an example:

If you're creating burrs big enough to start throwing shadows, all I can say is WOW.

cbw

 

[Cliff Stamp]

Where is this coming from? A few days ago, you were posting that burrs under magnification cast a shadow, now its casting shadows readily under light?

I used to primarily use low magnification, 10-20 times to inspect problematic edges and the burrs show as a very dark line on one side of the blade. Awhile back I spent some time refining my sharpening methods, specifically enabling push cutting fine paper with very coarse edges and found that I could see the burr by eye. This isn't a large shadow which blocks out the edge bevel, it is just a asymmetry which you can see as you rotate the blade. You can see it glint as well because the folded over edge will catch the light. The easiest way is to detect it is to just cut something as when an edge has a full burr form it will slice paper, and when it is edge biased with a burr it will shave on one side and not the other. You can also feel it if the burr is large when you clean the edge on papr or fabric as it will drag on one side and not the other.

Here's an example ...

Yes that is the primary burr which forms during the initial edge shaping, it looks like a saw tooth wave on occasion with large sections of steel hanging off. On soft knives the same thing can form up to 1-2 mm wide. That is cut off easily with some edge-into honing and you get secondary burr formation due to the metal bending and not being cut which induces an edge bias. This edge bias produces the variable light reflections I was speaking of in the above.

-Cliff

 

[cbwx34]

Wow... big difference. Telling a guy that's having trouble sharpening that "a burr will be visible readily under light as a part which will cast a shadow" now "it is just a asymmetry", and then adding other qualifiers, is not very helpful. I'm sure you mean well, but you really should take the time to read what you're typing. Readers aren't going to know what you mean... only what you say. Plus, if you're doing something specific, such as 'sharpening with very coarse edges'... you should state that, or at least realize it doesn't apply to the question.

I still say the easiest way to detect a burr is just to feel for it. With a little practice, you can feel very tiny burrs, because the sides just won't feel the same. An even better way of detecting problems is by using the Razor Edge Edge Tester (it has been commented that a BIC pen will also do this, but I haven't tried it). The RE test of pushing the tip along the edge will detect problems that can't readily be seen or even felt. The cutting and other tests you mention are only helpful for detecting problems that will be obvious using other methods.

I'm not sure what you mean by a "primary burr", but the photo is the remains of a burr that was belt sharpened and poorly stropped. I don't think it was an "initial edge shaping" but not my work, so can't really say.

cbw

 

[Cliff Stamp]

"a burr will be visible readily under light as a part which will cast a shadow" now "it is just a asymmetry"

The asymmetry is what causes the visible detection as since the edge is folded over you will see light both reflecting from the top part as well as a shadow under it. Rotate the knife and watch how it responds to the light. Under a lighted magnifier it is immediately visible. Yes if you are sensitive enough you can feel a burr, many people never go beyond that to judge sharpness.

... if you're doing something specific, such as 'sharpening with very coarse edges'...

It isn't specific to very coarse edges, and generally all sharpening starts there and you want to minimize the burr at that stage before proceeding.

I'm not sure what you mean by a "primary burr" ...

When edges are honed as to first meet there is often a strip of steel along the edge which was never cut off. On machetes this can be so large as to be visible as a distinct line of folded metal 1-2 mm wide. This jagged edge with bits of metal sticking off is what you get with no burr removal steps in the sharpening. After the first steps at burr removal this is gone and what you are left with an edge bias as the edge is folded from one side to another with each pass on the stone.

-Cliff

 

[cbwx34]

Yes if you are sensitive enough you can feel a burr, many people never go beyond that to judge sharpness.

My opinion, it's not that a sensitive touch is needed... it's more a matter of comparing sides, and you'll feel a difference.

It isn't specific to very coarse edges, and generally all sharpening starts there and you want to minimize the burr at that stage before proceeding.

You're the one that said it was... or at least made it seem that way...

Awhile back I spent some time refining my sharpening methods... with very coarse edges and found that I could see the burr by eye"

Reads like there was a difference to me... since you "found..."

When edges are honed as to first meet there is often a strip of steel along the edge which was never cut off. On machetes this can be so large as to be visible as a distinct line of folded metal 1-2 mm wide. This jagged edge with bits of metal sticking off is what you get with no burr removal steps in the sharpening. After the first steps at burr removal this is gone and what you are left with an edge bias as the edge is folded from one side to another with each pass on the stone. -Cliff

The way I learned it... those are both still just a burr... but I see your distinction.

cbw

 

[tim8557]

Faceplant, here is an excellent tutorial on sharpening. Take the time to download it; grab a 6 pack and a quiet corner. One you really understand the principles behind sharpening....the mystery goes away. You basically removing metal by abrading it with a harder surface. http://forums.egullet.com/index.php?showtopic=26036

 

[Nosmo]

I have never had a problem seeing a burr. Just got to have the angle and light right.

Burr below was formed on 220 grit.

 

[Cliff Stamp]

Reads like there was a difference to me... since you "found..."

That was just when I noticed it. It was mainly the effect of online conversations involving maximum sharpness specifically on coarse edges so I spent some time refining them to see how far I could go and determined that about 1-2" push cutting newsprint was personally optimal. In general the only issue with sharpness is only one of burr removal as that is all that remains after shaping the edge until the sides meet.

... those are both still just a burr...

Generally, they have distinct characteristics though both in forming as well as in performance. Primary burrs are debris and unhoned steel, secondary burrs are just deformed metal, you create them with use of a smooth steel instantly for example. Pretty much all knives are used with secondary burrs, all you can do is try to minize them. Primary ones are horrible though, they are generally what people mean by "wire edge" as they collapse immediately.

-Cliff

 

[cbwx34]

In general the only issue with sharpness is only one of burr removal as that is all that remains after shaping the edge until the sides meet.-Cliff

I'm not sure what you mean by this. What about edge angle, level of finish, type of steel, etc.? If you're saying burr removal is all that remains assuming the rest of the items are properly performed... I agree with that.

Pretty much all knives are used with secondary burrs...

Sorry, don't buy this one at all. I'm not sure what you're talking about as a secondary burr being "deformed metal". A pretty good burr definition is "the ridge or flap of metal created at an edge during an abrading process". (Leonard Lee). Even some of the edges in his book magnified to degree they are... are pretty burr and deformation free. Obviously, there would be some level of magnification that will show some deformation, but for all practical purposes it doesn't effect the performance of the knife. Burr removal, while not always easy, can be done... and once the burr is removed the edge can be honed without creating another one of practical significance.

cbw

 

[Cliff Stamp]

I'm not sure what you mean by this. What about edge angle, level of finish, type of steel, etc.?

Edge angle doesn't effect sharpness just cutting ability, edge grit similar. The steel and heat treatment can effect sharpness but as a user you can't really do much about that. All you can do is bring the edges to meet and cut off the burr, that is all sharpening consists of and the burr removal is the hardest part.

I'm not sure what you're talking about as a secondary burr being "deformed metal".

When you sharpen an edge on a stone there are two basic things happening to the edge. It is getting abraded and it is getting deformed. At some level the edge will always deform as it is under a force and isn't infinitely rigid thus there is always some side bias or burr formation.

A pretty good burr definition is "the ridge or flap of metal created at an edge during an abrading process". (Leonard Lee).

This is the primary burr, the secondary burr as I noted in the above is different both in how it looks, acts and is formed, primarily because it is formed of quality steel.

Even some of the edges in his book magnified to degree they are... are pretty burr and deformation free.

He ignored several factors in his pictures, Verhoeven shows much better details and notes that all you can do is minimize the burr and shows exactly how large it is for various methods. Most people would actually describe all his edges as burr free as what he is calling a burr is actually the thickness of the very edge. I am speaking of an asymmetry generally which is what most people mean. So for example if you steel an edge with a smooth steel you create a burr because it is deformed to one side.

Burr removal, while not always easy, can be done... and once the burr is removed the edge can be honed without creating another one of practical significance.

Secondary burrs are commonly formed right after the primary burr is removed simply because of the forces applied in sharpening. Note in Clark's commentary he notes after his burr removal step how careful you have to be not to recreate it with the final steps. You can minimize it with aggressive hones, wide contact area, etc. .

-Cliff

 

[cbwx34]

Thanks for clearing up how you define sharpness... guess it is just different than how I define it. Maybe I'm wrong, but you're the only one I know that has started defining primary and secondary burrs.

Sure. "At some level" you'll always have deformation. But I'm talking about on a practical level. If I went by your analysis, then I would never have to put gas in my car again. Because "at some level" there is always gas in the car.

But on a practical level... when you're outta gas, you're outta gas.

cbw

 

[D_R_Sharpening]

Flame me if you will folks but I have to say this...

What the hell is Cliff talking about?

Seriously, I've read and re-read all that has been written and like usual I have no idea what he's saying. Is this just me or is he arguing to argue? Maybe I'm too stupid to understand or he's too smart to explain?


--Dave--