No burr when sharpening but still sharp?

[DavidL41]

I sharpened a 154cm steel knife Rc 60, managed to get it relatively sharp. Problem is I never really gotten a burr on the knife, maybe a tiny bit of burr that I could feel hardly with my finger nail. I used 100 grit and 1500 grit dry wet sand paper - even the 100 grit couldn't get a noticable burr. I don't know if its necessary to get a burr to obtain the "highest" degree of sharpness but the knife is plenty sharp.

Has anyone sharpened steels like 154cm stainless steels wo/ creating a burr?

 

[Obsessed with Edges]

If you're using edge-trailing passes on wet/dry paper, that could account for the minimal burring. I've noticed the same on sandpaper, and it's one of the reasons I've liked sharpening with it, so long as relying on burr formation isn't the only means by which one can ensure a fully-apexed edge. Edge-trailing on sandpaper doesn't subject the apex to the same lateral stresses as with edge-leading on a hard stone, so burrs will be less likely to form under similar pressures, especially if the paper is used over a softish/conformable backing like leather or a mouse pad.

One way just to prove a burr can/will form on that particular blade at RC 60, is to sharpen it on a much harder hone with edge-leading passes under somewhat heavier pressure. Do this only if you really want to prove it'll burr; if your edge is already satisfactorily sharp, you may not want to. 154CM is supposed to be elementally similar (nearly identical) to ATS-34; if so, I know ATS-34 at high hardness will generate some amazingly tough & tenacious burrs that can be difficult to clean up.

MOST of the time, the lack of a burr means the edge isn't quite as finished as it could be, and taking it further to a thinner apex will eventually produce a burr. But even if it's somewhat short of that, the edge may still be 'sharp' enough (very subjective description) to still be useful.

Some (most, even) steels at high hardness can still form burrs; but they're often hard/brittle enough to quickly break away during sharpening, and may often be overlooked or missed, unless you're really watching for them. I have a nice 1095-bladed folder from Schrade that behaves this way, and I've almost never seen significant burrs on it. On the other hand, the high chromium (and molybdenum, I think) in 154CM/ATS-34 makes these steels very tough/ductile at higher hardness, so I don't see them breaking off burrs nearly as easily when they form, as the burrs can be much tougher.


David

 

[dkb45]

It is highly method and technique dependent, but you are most likely not getting the entire apex, so there is a practically microscopic micro bevel on the apex. I have had this happen a lot of times.

It is possibly that you could be experiencing no bur because the apex steel is jacked up from a borked HT, or burning from the factory grind. The HT is a warranty issue (but you could tell if the knife basically doesn't hold an edge), but the burning is usually fixable by just taking a little steel off. These are the least likely possibilities.

 

[bgentry]

It's entirely possible that you simply haven't reached the apex along the entire length of the edge. If that's true then you haven't seen how this blade will really perform once it's actually got a fully apexed edge.

Some quick evaluations of sharpness: Does it clean slice phonebook paper? Shave arm hair?

Brian.

 

[Fred.Rowe]

Edge-trailing on sandpaper doesn't subject the apex to the same lateral stresses as with edge-leading on a hard stone, so burrs will be less likely to form under similar pressures.

David

Give me your thinking on this David. I would think if the same angle were being maintained and the same pressure applied why would moving the edge in an opposite direction along the abrasive surface result in more or less burr being formed.

I believe if the knife blade is truly straight we are working with, [the geometry is consistent] and the blade is being held at a consistent angle, its possible to stop the abrading on side one at a point that is "half way to the center line of the blade" Turn the blade over and bring side two to the exact center line of the blade, AKA the apex. If the apex of the blade is not centered and aligned down the center of the blade, a burr will begin to develop at the spots along the edge that are out of alignment. It only takes a few thousands out of alignment to cause this.

If I profile an edge on the belt grinder in a manner that holds the edge at a consistent angle to the abrading surface, and the blade is geometrically sound, I do what is described above and bring the grind to the apex, without going beyond, [the start of a burr] on side one, then turn the blade over and bring the other side of the blade's secondary bevel to the peak of the apex. In this manner, no burr is created. Since I grind primary bevels using a control system the knives I build are geometrically precise, this makes possible the grinding of a perfect edge with out a burr developing.
From the 100's of blades I've sharpened I don't often find one that is ground "perfect" Many factory blades are not ground true. Some brands are less correct than others. Many customs are also ground off center. I admit, the tool I grind with gives me an advantage in grinding both primary bevels and secondary bevels, but then thats the goal, precision ground edges.

Regards, Fred

 

[Obsessed with Edges]

Give me your thinking on this David. I would think if the same angle were being maintained and the same pressure applied why would moving the edge in an opposite direction along the abrasive surface result in more or less burr being formed.

I believe if the knife blade is truly straight we are working with, [the geometry is consistent] and the blade is being held at a consistent angle, its possible to stop the abrading on side one at a point that is "half way to the center line of the blade" Turn the blade over and bring side two to the exact center line of the blade, AKA the apex. If the apex of the blade is not centered and aligned down the center of the blade, a burr will begin to develop at the spots along the edge that are out of alignment. It only takes a few thousands out of alignment to cause this.

If I profile an edge on the belt grinder in a manner that holds the edge at a consistent angle to the abrading surface, and the blade is geometrically sound, I do what is described above and bring the grind to the apex, without going beyond, [the start of a burr] on side one, then turn the blade over and bring the other side of the blade's secondary bevel to the peak of the apex. In this manner, no burr is created. Since I grind primary bevels using a control system the knives I build are geometrically precise, this makes possible the grinding of a perfect edge with out a burr developing.
From the 100's of blades I've sharpened I don't often find one that is ground "perfect" Many factory blades are not ground true. Some brands are less correct than others. Many customs are also ground off center. I admit, the tool I grind with gives me an advantage in grinding both primary bevels and secondary bevels, but then thats the goal, precision ground edges.

Regards, Fred

My view on it is from the standpoint of the direction the apex is moving in relation to the abrasive media, and it's tendency to 'bite' or dig into the hone/stone during edge-leading movement over it, greatly magnifying the pressures exerted into the apex and laterally against the edge. When edge-trailing, the tendency for the edge to bite into the stone (or whichever media is used) is essentially nil, and therefore reduces the likelihood of the thin steel at the edge folding over ('burring').

I'd noticed the differences almost immediately when I first started tinkering with edge-trailing sharpening (by hand, not with driven belts). As compared to edge-leading, when it was very easy to feel the increase in pressure when the edge is moving into the hone, the pressures felt in edge-trailing were much lighter, and I also noticed a much lesser tendency for heavy burring as a result, and even less when doing so on somewhat forgiving backing under the paper.

I mentioned sharpening by hand, specifically, because I'd expect it's different with driven sharpening media (belts, wheels), due to the velocity of the driven media. I know a lot of it comes down to pressure exerted (I'm convinced this is most of what generates burrs and makes them larger), and skill/technique play into it as well. But my impressions early on made it fairly obvious to me that it was much easier to minimize burring with an edge-trailing stroke, which is why I mentioned it.


David

 

[Fred.Rowe]

My view on it is from the standpoint of the direction the apex is moving in relation to the abrasive media, and it's tendency to 'bite' or dig into the hone/stone during edge-leading movement over it, greatly magnifying the pressures exerted into the apex and laterally against the edge. When edge-trailing, the tendency for the edge to bite into the stone (or whichever media is used) is essentially nil, and therefore reduces the likelihood of the thin steel at the edge folding over ('burring').

I'd noticed the differences almost immediately when I first started tinkering with edge-trailing sharpening (by hand, not with driven belts). As compared to edge-leading, when it was very easy to feel the increase in pressure when the edge is moving into the hone, the pressures felt in edge-trailing were much lighter, and I also noticed a much lesser tendency for heavy burring as a result, and even less when doing so on somewhat forgiving backing under the paper.

I mentioned sharpening by hand, specifically, because I'd expect it's different with driven sharpening media (belts, wheels), due to the velocity of the driven media. I know a lot of it comes down to pressure exerted (I'm convinced this is most of what generates burrs and makes them larger), and skill/technique play into it as well. But my impressions early on made it fairly obvious to me that it was much easier to minimize burring with an edge-trailing stroke, which is why I mentioned it.


David

That makes sense. I think its mostly a matter of pressure. When moving the edge into the abrasive on a stone or plate there is more resistance and more pressure is needed to overcome the resistance; the reverse is true when trailing the edge. I would imagine when moving to finer stones or diamond grits the sensation would be less. I do sharpen on diamond plates 400-630-1000 grits, but this is after I come off the 2 x 72 belt machine, where the technique requires more of a steady hand with less pressure. Of course with the belt the process happens so much faster, developing a burr is less of an issue. I avoid creating a "large burr" if possible, they are so much harder to deal with and finishing the edge after they are removed takes more effort and better technique.
I re-profiled a Cargill folder out of Texas today, it had an edge that could hardly be observed, it was so small a glass was needed. It had been passed through some type of small wheels, so the edge was small and concave and therefor weak. It felt sharp, but dulled almost instantly with use. I tried to fix it on the diamond plates, first at 12 degrees, switched to 15 degrees and saw the job was to big, I switched to the belt machine using 320-400-600 cork using the 15 degree setting; I finished with a few passes on the 1000 grit diamond then completed the edge using an ERU set at 30 degrees, switching to a 32 degree micro bevel to top it off. It took me and hour even with the powered machine. When I finally looked at it end on I could see the blade was skewed off center. Sharpening will keep your mind sharp thats for sure

Thanks for your response David. Regards, Fred

 

[Jens Schuetz]

I always read about burrs here too but never got one. With VG10, Super blue, 440, M390, S35VN, ATS34, Aus8 or any other steel.
Weird.
I use the apex pro system trailing with sharpie and magnifying glass.
Also I stop when they shave my arm hair. Sometimes they shave face hair too but that's not my goal.

 

[DavidL41]

knife can shave hair decently, and can cut paper, but this time I can see that it isn't cutting it 100 percent cleanly. Im not using any good stones, just sandpaper. Even 100 grit no burr on carbon.

The only time I have gotten burr is on mystery stainless kitchen knife.

Maybe I need ceramic stones?

 

[JasonECornu]

I never really get burrs on my edge when I sharpen. I use Arkansas soft then hard stone, 1000 then 2000 grit wet/dry paper and finish with an extra fine ceramic. I know the edge is good when it can push cut receipt paper.

 

[Obsessed with Edges]

knife can shave hair decently, and can cut paper, but this time I can see that it isn't cutting it 100 percent cleanly. Im not using any good stones, just sandpaper. Even 100 grit no burr on carbon.

The only time I have gotten burr is on mystery stainless kitchen knife.

Maybe I need ceramic stones?

If by 'I can see it isn't cutting it 100 percent cleanly', you mean it's snagging in the paper? If so, I'd bet there IS a burr there, at the points where it snags. That's the value in the paper-cutting test; it'll reveal very fine burrs that otherwise might not be seen or felt on the fingertips. If the poor cutting is because the edge is just slipping over the edge of the paper, then it may just be an incomplete apex at those spots; sometimes, burrs that are completely rolled over will also cause it to slip, but that's a bit less likely.


David

 

[Chris "Anagarika"]

David, Fred,

Thank you. Learnt something else today. I was under impression that edge leading on DMT minimizes burr.

 

[HeavyHanded]

Chris,
I believe your impression re DMT (and other hard media) is correct. The dynamics of burr formation and removal tend to be heavily influenced by how hard the abrasive surface is, how firmly affixed the abrasive is to that surface, and (less applicable to freehand work) how fast the abrasive is moving.

A trailing movement on DMT might dig less deeply into the steel, but also is the most inefficient angle to cleanly remove the steel as it exits the apex. Leading might dig a tad deeper but is also more effective angle of attack to minimize burr formation.

 

[Obsessed with Edges]

David, Fred,

Thank you. Learnt something else today. I was under impression that edge leading on DMT minimizes burr.

With good technique (very light pressure, consistent angle control), I'd say you're right, as compared to other 'hard' stones/hones I've used. Diamond cuts so cleanly, that even feather-light pressure is enough to work. On less-hard abrasives, especially when used in stone/hone form (sandpaper & loose grit aside), a little more pressure would be needed to make them work as aggressively as diamond. Pressure is what makes the difference with burrs.

I've really grown to like using diamond for the reason above. I've finally found a touch that works very well with it, and results are getting way better for me. This means I'm getting very crisp edges and minimal burring, to the point I often don't even feel the need to strop afterwards. The same improved touch is also yielding better results on all other hones I'm using (SiC, AlOx, ceramic, Arkansas), so I know I've found something fundamentally sound.

I mentioned good angle control above, because with edge-leading, any tendency to roll the blade (and apex) forward into the hone will greatly magnify the force exerted against the apex, and therefore increase the likelihood of burring, or generating heavier burrs. Part of the improved 'touch' I mentioned above, has been in finding a steady way to hold the blade & hone while working, which both minimizes any tendency to roll the blade forward, and also maintains the pressure at a very light level. I think everybody should really pay attention to how they hold the blade (and hone, if not used on the bench), and stay aware of how that is affecting angle control and pressure. It really pays off big, when a means is found to control those two variables in a consistent and repeatable manner.

The reason I mentioned the ease of edge-trailing on sandpaper (specifically), is because it's MUCH more forgiving of inconsistencies in angle control and pressure (to a finite point). When I first started using sandpaper, my own technique was still in need of 'improvement' (ahem), but I still noticed it was much easier to minimize burring and produce some pretty good edges; that's what got me hooked on that method in the first place, as it was working better for me than anything else I'd tried 'freehand'. In fact, I think that's what finally started to 'liberate' me of my dependency on guided sharpening at the time, so I was thrilled.


David

 

[Fred.Rowe]

With good technique (very light pressure, consistent angle control), I'd say you're right, as compared to other 'hard' stones/hones I've used. Diamond cuts so cleanly, that even feather-light pressure is enough to work. On less-hard abrasives, especially when used in stone/hone form (sandpaper & loose grit aside), a little more pressure would be needed to make them work as aggressively as diamond. Pressure is what makes the difference with burrs.

I've really grown to like using diamond for the reason above. I've finally found a touch that works very well with it, and results are getting way better for me. This means I'm getting very crisp edges and minimal burring, to the point I often don't even feel the need to strop afterwards. The same improved touch is also yielding better results on all other hones I'm using (SiC, AlOx, ceramic, Arkansas), so I know I've found something fundamentally sound.

I mentioned good angle control above, because with edge-leading, any tendency to roll the blade (and apex) forward into the hone will greatly magnify the force exerted against the apex, and therefore increase the likelihood of burring, or generating heavier burrs. Part of the improved 'touch' I mentioned above, has been in finding a steady way to hold the blade & hone while working, which both minimizes any tendency to roll the blade forward, and also maintains the pressure at a very light level. I think everybody should really pay attention to how they hold the blade (and hone, if not used on the bench), and stay aware of how that is affecting angle control and pressure. It really pays off big, when a means is found to control those two variables in a consistent and repeatable manner.

The reason I mentioned the ease of edge-trailing on sandpaper (specifically), is because it's MUCH more forgiving of inconsistencies in angle control and pressure (to a finite point). When I first started using sandpaper, my own technique was still in need of 'improvement' (ahem), but I still noticed it was much easier to minimize burring and produce some pretty good edges; that's what got me hooked on that method in the first place, as it was working better for me than anything else I'd tried 'freehand'. In fact, I think that's what finally started to 'liberate' me of my dependency on guided sharpening at the time, so I was thrilled.


David

This is exactly why I ship a full set of accurate degree wedges with the ERU sharpener. If the user cannot develop an actual "flat" cutting bevel there is no way to progress. Once an edge is "flat" it is easy to maintain.

Fred

 

[DavidL41]

fred that is exactly the issue. The bevel wasn't flat, either from the factory or from me putting more pressure on one side of the knife (most likely). There was only one side that had any metal coming off it, so I could tell one side was thicker than the other.

The way I got it flat was sharpening until I established a flat even bevel, then a metal hammer was used to strike the bevel until it flattens the steel (chisel blade). It was also a case of the metal not getting thin enough, which is what some of you guys recommended and was absolutely correct. The thing that was confusing was that I was apexing but the edge wasn't thin enough for a burr to form.

The thing now is that I can't say with certainty that the bevel is flat as some areas of the chisel are slightly sharper, seeing as how there are peaks on the bevel. Do you use something like a DMT stone w/ a flat surface for a fast way to flatten the bevel?

 

[Obsessed with Edges]

fred that is exactly the issue. The bevel wasn't flat, either from the factory or from me putting more pressure on one side of the knife (most likely). There was only one side that had any metal coming off it, so I could tell one side was thicker than the other.

The way I got it flat was sharpening until I established a flat even bevel, then a metal hammer was used to strike the bevel until it flattens the steel (chisel blade). It was also a case of the metal not getting thin enough, which is what some of you guys recommended and was absolutely correct. The thing that was confusing was that I was apexing but the edge wasn't thin enough for a burr to form.

The thing now is that I can't say with certainty that the bevel is flat as some areas of the chisel are slightly sharper, seeing as how there are peaks on the bevel. Do you use something like a DMT stone w/ a flat surface for a fast way to flatten the bevel?

Might be helpful to post a pic of your blade, so we have a clearer picture of what you're describing.

For a chisel-grind, a flat & hard hone would definitely be best, and I'm sure a DMT could handle it. Something like a Coarse (DMT 'blue' 325), or maybe even an XC (DMT 'black' 220) should be able to quickly reset a flat bevel on it. The fewer passes it takes, the less chance for variation in the angle causing it to round off; hence a coarser diamond hone is what I'd use for that.


David

 

[DavidL41]

I have the picture on my computer that I can't find an option to post an image except through url.

The shoulder of the bevel isn't straight, slightly c shaped. It cuts fine but I would prefer to slowly fix this shoulder line.
Blade is also laminated, the area where you can see where the line between the soft iron and hard iron is not even like the shoulder line (less hard steel on the edges).

 

[Chris "Anagarika"]

David,

Thank you. Your two hands (one hone, one blade) inspired me to keep trying coming back to DMT EEF (yes, I shave with my knives). :thumbup:

Martin,

Your short passes is what enables me to fix those errors