Microbevels

Forgive me if this has been covered; I didn't have time to read the entire thread. What is the minimum angle difference that still allows a microbevel to be useful? Is 5 DPS enough? Should it be more like 10? Thanks!

I think 3-5 dps is a very good angle difference. A 10 dps difference is ok if the bevels are already at a very low angle. But for most EDC pocket knives 5 dps is good. My opinion of course. But if you don't have a sharpening system where you can set the exact angle the actual angles are an educated guess. If sharpening by hand the micro bevel may be harder to see because the bevels are already a bit convex.
 
I've been sharpening my new KA-BAR BK14, on KA-BAR's product page for the knife, it says that the edge angles are 15 degrees. I use a Lansky 4 Rod Turn Box for sharpening, I've got fine grit ceramic, medium grit alumina ceramic, & medium diamond grit rods. I started off with the diamond medium grit rods at first, to re-profile the edge to 20 degrees per side. Because the Lansky Turnbox only has two pre-drilled angles to choose from; 20 & 25 degrees, vs the Sharpmaker's 15 & 20 degrees. I kept sharpening on the diamond rods until until I had no more resistance running down the rods, the strokes were smooth and not grinding anymore. Then I moved to the medium alumina rods, doing the same, then finally to the fine grit ceramic rods.

The scratch pattern on both side seem even, I have several jeweler's loops at different power's to examine the edge, 10x, 20x, & 30x (singlets, doublets & triplets). I've also got a 2x magnifying glass with 10x spot lens (glass, not acrylic). On the left side of the blade there is a microbevel, but on the right side there is none. What should I do?, should I go back to sharpening & work on the right side until a micro bevel forms?. By the way, it is cutting though thin shopping ad papers quite nicely, as it is at the moment.
 
I'll also this, I like to start of by doing five strokes per side, then down to four stokes per side, & continue on down to one stoke per side, until I feel the passes are smooth and even. That's when I switch to the lower grit stones, I just want to be clear about that.

Edit: I was cutting up a wooden clothes pin in my room, & when I went to split it in half, I cut into the tip of my thumb as well. :shame:
 
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I try to do as little micro beveling as possible, I find that my micro beveled edges die down much faster than just a standard apex sharpened edge. If you have a really thin cutting bevel, I see how this might help. I dunno, ever since I got into sharpening, the Spyderco system was the first sharpening tool I had, and I always wondered to my self "why aren't I getting a mirror polish? and why do my edges go dull after a couple cuts compared to my factory edge?"
I didn't understand what was happening with the sharpmaker back then. I try to never micro bevel, its just my thing. I do sometimes to save on time and steel, but thats it. My take on the micro bevel is, you are now putting that tiny 1 or 2 mm piece of metal up your material instead of that whole edge, just seems like less steel being stressed, which in tern means weaker. I'm probably wrong but that is just how I look at it.
This is interested though about the original post.
 
There's a lot of good info in this thread. Some of it is here, some of it is there. So I typed up my thoughts about micro-bevels and why to use them or not to use them. All of this is just my opinion. Others may agree or disagree. Here goes.

MICROBEVELS, my thoughts

Fact 1: The thinner the blade the better a knife will cut.

Fact 2: The lower the edge bevel angle the better the knife will cut because lower angles result in a thinner blade edge.

Fact 3: The blade needs to be thick enough to hold up to the work it is intended for.

Fact 4: The edge bevel angle needs to be high enough to reduce chipping, rolling, flattening or anything that results in a dull edge.

So there is a “middle of the road” that is best for any given knife depending on it’s use. Example: You wouldn’t use a straight razor to cut fire wood and you wouldn’t use an ax to shave with. These cutting tasks I’d say fall at the outsides of the “road”. For an EDC pocket knife you need something between the razor and ax.

I have two reasons to use a micro-bevel instead of one bevel. First, lets talk about the size of the bevel(s) on a knife edge. Let’s say you sharpen a knife with one bevel until it is sharp. Then you raise the angle and put another bevel on the edge apex. The first, larger bevel we’ll call the back-bevel. The bevel at the edge apex I call a micro-bevel when it’s small enough that it’s hard to see. If the bevel on the edge apex (cutting edge) is easily seen I like to call an edge-bevel. I like to distinguish between the two bevels based on size because of the benefits or reasons to use them.

1. MICRO-BEVEL: I use a micro-bevel only as a finishing step to ensure there isn’t a burr and as a very fast touch up. The angle is higher and as a rule of thumb a higher angle will decrease cutting performance. But with such a tiny micro-bevel it won’t decrease cutting performance enough to notice in my opinion.

2. EDGE-BEVEL: A wider bevel at the cutting edge will strengthen the edge apex against chipping, rolling, etc. The wider bevel will decrease cutting performance more but not nearly as much as it would if the entire edge were at this higher angle. Actually, in my opinion for an EDC pocket knife neither the micro-bevel or larger edge-bevel will decrease cutting performance enough to notice.

So the reasons I use a micro-bevel are to quickly touch up an edge at a higher angle than the main bevel or primary bevel or whatever you call it. Different people use different terms for these bevels as well as the entire blade grind. The other reason I’d use a different angle on the edge apex is to strengthen the steel right at the cutting edge and the lower angle back-bevel thins the blade which increases cutting performance. Since (IMO) cutting performance isn’t reduced enough to notice I see not reason NOT TO USE a micro-bevel. It will strengthen the edge apex a bit and also make touch ups easier and faster.

SHARPENING METHODS and how they affect using micro-bevels (sharpening system or free hand)
Sharpening system: Using a system that you set the angle with allows two separate, accurate, flat bevels at different angles. I’ve used systems before and I like to keep a record of the angles on each knife so when performing a touch up I can set the angle for the micro (edge)-bevel to what I set the sharpener to the last time I sharpened the knife. Personally, I thing the edge or micro-bevel should be 3-5 degrees higher per side for it to make any significant difference in edge strength. If you want to use a higher angle on the apex only to ensure you are hitting the apex with the stone or for a very quick touch up just one angle higher is enough. To do this however you will need to have recorded your micro-bevel angle for that knife or use a marker to re-set the sharpening system to the same angle.
Free hand: When free hand sharpening it’s impossible to create completely flat, accurate bevels due to human inconsistency. Therefore all bevels will be slightly convex. The edge bevel angle at the edge apex will always be higher than the angle at the top of the bevel. Therefore the apex is by nature stronger than it would be if the bevel were flat at the same angle as the top of the bevel. But if you want the angle at the apex even higher you can intentionally raise the angle a little more. Just a little practice and putting a micro-bevel on a knife free hand is quite easy.

I’m sharpening free hand right now and haven’t used a system in a couple of years probably. Since I don’t have a way to set an exact angle or have two separate flat bevels I touch up the edge by “feeling” when the edge apex makes contact with the stone. When a convex bevel is sliding along the stone it “feels” very smooth with no or very little resistance. I’ll slowly raise the blade spine until I “feel” the apex make contact. There is a sudden increase in resistance to the sliding motion along the stone. Once I “feel” this I do my best to keep the angle the same and not increase the angle any. The end result is usually what appears to be one consistent bevel. In reality however (this is how I look at it) the edge bevel is higher than the rest of the bevel.

NOTE ON FREE HAND ACCURACY AND HITTING THE APEX: Since I (no one) is 100% accurate throughout one complete stroke when we try to hit the apex with 100% accuracy we will go too high as often as going too low. Therefore to ensure I don’t increase the edge or micro-bevel angle any higher than I want I repeat strokes trying to err on the side of too low of an angle. My inaccuracy will still ensure I hit the apex enough to put a hair whittling edge on the knife. This theory is something I understand (I think) but it is also something you can’t get the “feel” of overnight. Even when we do have the “feel” for this we are still not 100% accurate. When using a sharpening system you don’t need to “feel” for hitting the apex. What you do need to “feel” for is the amount of pressure which also is essential when trying to achieve the super-sharp levels.

Again, all of this is just my opinion. As I learn more and get more experience my opinion often change.
 
Swedish traditional knifes has around 20 degree total edge angle. If you by a Mora knife it holds around 22 degree total edge angle.
Swedish knifes edge design comes from traditional wood work.

If the knife was used for other things then wood work it was common to make a "hooning edge". The honing edge shall be 2-3 tens os 1 mm wide. When you can se this edge with your naked eye - it is ready. Start with 2 degree honing edge and then use the knife.

If you like ghe edge sharper, change the honing edge to 1-1,5 degrees. If you like måla more durable edge, change the honing edge to 2,5-3 degrees. This is named "balancing the edge".

When you change an normal flat edge from 10 to 11 degree DPS. You "add" 1/1000 of 1 mm more material to the edge. That is not much...but it is much. The 10 degree edge is 20/1000 parts of 1 mm thick. When you regrind the edge to 11 degree you add 2/1000 parts of 1 mm, that is 10 % more material you add to the edge, that is much.

I have not calculate how many percent you add to the edge when you make an honing edge - but it is much more then in the example above becouse you work with a small tiny edge, just 2-3 tens of 1 mm wide - and this edge is really "steep"

The result is a much strong edge - and the friction against the material you work in is still low bexouse of thatvthe main edge is still 20 degrees total edge. What you get is a nice, still very sharp, edge with low friction.

Thomas
 
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This is a drawing off what I try to explain above.

I shall try to make a new drawing that show the same thing with a honing edge instead.

Thomas
 
Hi there,

I become a member 2004 so I am a "old member", not so Active today. You know what I am working with and some people here think that I marketing that when I write something :) so I dont write so much. I try to explain things sometimes, as above.

I am fine and enjoy my Life here out in the forest. I drink my whisky, smoke my cigarrs, and sit in front of the fire when I have the time for it- if my wife have chop the firewood and make up the fire for me :)

Thomas
 
I'm another who doesn't microbevel. I generally straight bevel sharpen, then strop on 4 strop blocks of increasing grit, which puts a very slight convex on the edge.
 
I have been sharpening knives for about 60 years. About 50 years ago I would go door to door sharpening knives. Back in the day the sharp knives were either simple carbon steel or an alloy with vanadium. These would match the common expectation that you could hone to an arbitrarily low angle and get a smooth and stable cutting edge. I would often use a fine grinding wheel and hollow grind edges to enable straight razor sharpness. I even did that on Italian push button knives with serpentine blades.

A few years later all of that started breaking down as premium knife makers started sacrificing acuteness for greater hardness, toughness or corrosion resistance. The Buck 110 locking folder initially had a 440C blade that was hard, stainless, but resisted taking a traditional razor edge due to the coarseness of its alloy granularity. The Gerber knives used M2 tool steel which was very abrasion resistant, but very tough to sharpen. The Japanese kitchen knives were often made using stainless alloys with molybdenum in them. Those were also quite different from carbon steels or vanadium alloys. The stainless alloys (particularly the harder ones or cheaper ones) would not take a fine single bevel without some extra work. I was all for the work, but at times I had to explain to an amateur how to get a shaving edge on these recalcitrant alloys. It was not simply a quicker way, it was often the most effective way for these alloys. Basically I told them to use something close to a 15 degree back (or primary) bevel until they had the sharpest edge they could achieve. Then use very, very light pressure and strokes on alternate sides to apply a micro-bevel. 20 degrees would be about right and a total of about 4 strokes per side. This eliminates burrs and cleans up residual roughness due to the coarseness of the alloy granularity relative to the micro edge bevel.

A major factor in all this diversity of approach and opinion relative to the necessity and purpose of micro-beveling relates to different alloys. If you have a 1084 carbon alloy pocket knife you don't need to micro-bevel. If you have one of the primary vanadium alloys like some of the Scandinavian blades the micro-bevel can be optional. With BG-42 I didn't have a need to micro-bevel. On the other end of the spectrum D2 is notorious for a coarse grain structure and I would likely micro-bevel.

For stainless kitchen knives I micro-bevel then go back and remove the micro-bevel with some secondary honing at the 15 degree angle. That is also what lets me achieve ultimate sharpness on an SAK without needing to go back to stropping with 100,000 grit diamond paste.
 
Nice to see you guys as well. I have been busy. For example in mid January I fractured my skull, got a concussion and brain trauma. Tomorrow I go back to work.
 
For stainless kitchen knives I micro-bevel then go back and remove the micro-bevel with some secondary honing at the 15 degree angle. That is also what lets me achieve ultimate sharpness on an SAK without needing to go back to stropping with 100,000 grit diamond paste.

Jeff, that is some interesting history---thanks for posting it.

Can you talk a bit more about the quote above. Some sharpeners recommend a couple of swipes at a higher angle to remove the burr, and then following with a few more at the original angle to finish. Is that what you're describing, or something different?

Andrew
 
With old carbon steel blades and meat cutting duty I never really worried about a burr. A really acute edge flexes away from your hone and near the edge the surfaces of the bevel stops looking like a V and starts looking like || over a 'v'. This is what a straight razor honer would call a 'fin'. If you don't need much more durability than a straight razor you can simply strop the blade lightly and straighten up the fin and any burr. The combination does a tremendous job of slicing through meat and is good for shaving if the alloy is sufficiently smooth and ductile. At one point I considered a micro-bevel as a way to remove the burr and get back to a V with less of a fin.

That all makes sense when you are not dealing with coarser alloys. With an alloy with coarse hard grain and hard alloy inclusions edge roughness can be poorly abraded grains at the edge. Think of it as being like trying to sharpen concrete with gravel in it. If you are not using a fine diamond grinder you can't get the edge finer than you could mold the cement plus gravel structure. My old experience with carbon steel was a bit like sharpening Popsicle sticks. If you honed the sticks on the sidewalk to a low angle you could see the wispy burr along the edge. You could slice that off and get a better edge with a sharp knife. On the other hand if you tried to hone a piece of terracotta pot (with smooth fine clay) you would get a fine edge with no burr or lumpy edge. You were out of luck honing coarse cement or concrete.

You can get an edge that is finer than the grain structure of your alloy if you use a sufficiently fine diamond abrasive. If you microbevel you can get a bit between an arbitrary fine edge and the grit structure. You actually can hone a V structure onto the coarse hard grains and leaves the grains with a pretty secure support structure underneath (behind) the apex of the edge. This lets you get a finer than normal edge with reasonable durability. If you go overboard with the diamond hone and an extensive acute bevel you get the extreme razor edge, but it may break down faster. The support structure can be less than a grain wide and lets the grains get pushed out easier.

Anyway this last kind of microbevel is the kind I am presenting. While it will get rid of the burr and refine the fin it is primarily to improve edges and edge durability for alloys with coarse grain structure and inclusions.
 
Jeff was one of the first people I saw use the sharp maker for microbeveling. Hey Jeff how's it going.

Microbeveling seems to have gotten way more complicated than when I learned about it. Then it was just a way to speed sharpening on inherently slow cutting stones of finer grit, while saving wear on the same stones, which are typically more expensive.
 
Jeff was one of the first people I saw use the sharp maker for microbeveling. Hey Jeff how's it going.

Microbeveling seems to have gotten way more complicated than when I learned about it. Then it was just a way to speed sharpening on inherently slow cutting stones of finer grit, while saving wear on the same stones, which are typically more expensive.

This is how I still look at it. I most often use them as a shortcut from a coarse or medium to a finer hone or surface. Often on these jumps one can still see much of the pre-existing grind pattern but it's been worked thin...at a more broad angle - if that makes sense. The mean width across the edge is less but joins at a wider angle. In this way the edge gets a lot "sharper" and there is no functional loss of acuteness, the opposite actually.

Here's an old pic of one done IIRC on a Ik Norton waterstone and partially micro'd on an 8k mostly edge trailing. You can see the frosted surface from the lapping action of the 1k, virtually burr free grinding. The 8k overlay makes this a real fast one-two treatment and allows a bit of customizing - more passes = better pushcutting/fewer passes = better draw.

I use a similar approach on DMT's going from coarse or maybe a fine to the EEF. I normally do not microbevel unless it is with a much finer honing surface - the only consistent exception is when restricted to working with very coarse abrasives.
BCMW_52100_100_zpspnmtjc9e.jpg~original
 
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