micro bevel vs relief grind / double bevel

[stevelenti]

Most stuff I read talk about applying a micro bevel with just a few light strokes on both sides with the highest grit or maybe 1 stone down. I have also read setting a relief bevel at say 15 degrees then dropping in grit and raising a burr again at 20 degrees and progressing through the stones.

The other night I tried setting a relief bevel at 15 degrees progressing from Shapton 500 up to 6k. Then set the angle to 20 degrees, dropped back down to 2k, raised a burr (didnt' take much), and progressed to 4k and 6k both times raising a burr and removing it at the end. I use a little hand held microscope to help see the burr at that level.

I haven't been sharpening that long but this was by far the sharpest I have got an edge. So my question is... Is there any advantages / disadvantages to doing what I did over just setting a micro bevel with few passes with the highest grit stone? I know that some of this is just terminology but I have seen people say "they call it a micro bevel for a reason". So in this case I would not call what I did a "microbevel" but more a double bevel.

-Steve

 

[Fred.Rowe]

Hi Steve,

It seems that you are repeating the process of sharpening. When sharpening the edge at 15 DPS raising a burr and removing it, then doing the same at 20 degrees I believe is redundant. If the edge is sharp at 15 and you change the angle to 20 degrees to micro bevel with a few passes or you raise a burr again at 20 and remove it is repeating the process. May be it was meant to be sharpened at 20 in the first place. A micro bevel to me is a technique which addresses the apex only after sharpening at a more obtuse angle. Using a micro bevel does not change the edge angle hardly at all especially if its applied with but a few strokes. I use an ERU to strop and apply micro bevels. I change the angle between the sharpening position and the micro by a degree, no more than two. Its a way of cleaning up the edge that was missed during the sharpening process.
I'm sure others will post, Fred

 

[bgentry]

In the past I've done a similar process with micro bevels. Going through two stones at the primary (15 dps) and the same two stones at 20 dps. I think for me, the magic was mostly because I wasn't all that good at forming a full length burr. So forming what I thought was a good burr (but really wasn't) at 15 degrees was just "ok" results. Then raising the angle up made the target area smaller, and I was able to form a full length burr at the new angle much easier. I too experienced VERY sharp edges when microbeveling with this technique, compared to not using a micro. Again, this was just me and my lack of skill.

One interesting thing to consider about micro versus primary is the having a different finishing stone on each. This may seem backwards, but consider this:

Primary (back bevel) finished to a fairly high polish. Say your 6k water stone.
Micro bevel applied and finished fairly coarse. 1k JIS or under.

This makes the cutting edge "aggressive" and "toothy", while keeping a very polished back surface that should glide through material when pushed or dragged because the friction is so low. Just something to think about.

Brian.

 

[Obsessed with Edges]

Hi Steve,

It seems that you are repeating the process of sharpening. When sharpening the edge at 15 DPS raising a burr and removing it, then doing the same at 20 degrees I believe is redundant. If the edge is sharp at 15 and you change the angle to 20 degrees to micro bevel with a few passes or you raise a burr again at 20 and remove it is repeating the process. May be it was meant to be sharpened at 20 in the first place. A micro bevel to me is a technique which addresses the apex only after sharpening at a more obtuse angle. Using a micro bevel does not change the edge angle hardly at all especially if its applied with but a few strokes. I use an ERU to strop and apply micro bevels. I change the angle between the sharpening position and the micro by a degree, no more than two. Its a way of cleaning up the edge that was missed during the sharpening process.
I'm sure others will post, Fred

In a nutshell, there it is. :thumbup:

If an edge ends up 'sharper' after applying a microbevel, it's proof-positive that something wasn't fully executed or finished in the shaping and apexing of the first (primary) bevel. Applying the micro makes it much easier to finish a full apex and/or finish scrubbing off the burr created in the grinding of the primary bevel. Part of what makes it easier is in the fact it only takes a pass or two (ideally just one per side) to create the micro; that reduces the chances of erroneous additional passes that might otherwise slightly round off or blunt the apex on the primary's edge. By contrast, if trying to make a primary as sharp as possible without a microbevel, it takes much greater care to fully clean it up and maintain it's apex as crisp as possible, without rounding/blunting it slightly, or unintentionally creating a new microbevel on it. This is why it's pretty common to notice the edge is 'sharper' after raising the angle slightly, because it's an easier way to fully apex the edge in a minimum of strokes.


David

 

[stevelenti]

In the past I've done a similar process with micro bevels. Going through two stones at the primary (15 dps) and the same two stones at 20 dps. I think for me, the magic was mostly because I wasn't all that good at forming a full length burr. So forming what I thought was a good burr (but really wasn't) at 15 degrees was just "ok" results. Then raising the angle up made the target area smaller, and I was able to form a full length burr at the new angle much easier. I too experienced VERY sharp edges when microbeveling with this technique, compared to not using a micro. Again, this was just me and my lack of skill.

My "magic" could definitely be a lack of skill. I have learned a lot over the last few months and my edges show improvement but I know I still have lots to learn and refine in my technique.

I keep reading references online to a book titled "The Razor Edge Book of Sharpening" which I guess talks about always grinding a relief grind to thin the blade behind the actual edge then setting the edge like you normally would. From what I understand, pretty much what I did the other night. Here is one site that talks about the technique and references the book.

http://www.caseyspm.com/Knives.html

I just wasn't sure if there was a big difference to doing it this way or doing it with a microbevel (couple of strokes on each side).

Thanks for the responses.

-Steve

 

[stevelenti]

In a nutshell, there it is. :thumbup:

If an edge ends up 'sharper' after applying a microbevel, it's proof-positive that something wasn't fully executed or finished in the shaping and apexing of the first (primary) bevel. Applying the micro makes it much easier to finish a full apex and/or finish scrubbing off the burr created in the grinding of the primary bevel. Part of what makes it easier is in the fact it only takes a pass or two (ideally just one per side) to create the micro; that reduces the chances of erroneous additional passes that might otherwise slightly round off or blunt the apex on the primary's edge. By contrast, if trying to make a primary as sharp as possible without a microbevel, it takes much greater care to fully clean it up and maintain it's apex as crisp as possible, without rounding/blunting it slightly, or unintentionally creating a new microbevel on it. This is why it's pretty common to notice the edge is 'sharper' after raising the angle slightly, because it's an easier way to fully apex the edge in a minimum of strokes.


David

Actually, I never said it was sharper after the secondary bevel (Edit: I guess I kind of did, but that's not really what I meant). I should have been more clear. It's sharper with a 15 degree relief bevel and 20 degree primary bevel then knives I have sharpened in the past with just a 20 degree primary bevel. It was very sharp with just the 15 degree primary edge before adding the secondary bevel. I would imagine it was sharper, actually. I wasn't looking to do a comparison so I really didn't spend any time comparing what I had with just the relief bevel and what I got after but what I got after was clearly sharper than any of my other knives that were just shapened at 20 degrees without the 15 degree relief bevel.

15 degrees = sharpest
15 degree relief w/ 20 degree primary = more sharp
20 degrees = sharp

Any of these edges will cut phone book paper and shave. But there is a definite difference between the bottom two.

-Steve

 

[stevelenti]

Also, when sharpening I do raise the angle slightly on my two highest stones to ensure I am hitting the apex. I even check for a burr with a 60x-100x microscope.

-Steve

 

[Obsessed with Edges]

Actually, I never said it was sharper after the secondary bevel (Edit: I guess I kind of did, but that's not really what I meant). I should have been more clear. It's sharper with a 15 degree relief bevel and 20 degree primary bevel then knives I have sharpened in the past with just a 20 degree primary bevel. It was very sharp with just the 15 degree primary edge before adding the secondary bevel. I would imagine it was sharper, actually. I wasn't looking to do a comparison so I really didn't spend any time comparing what I had with just the relief bevel and what I got after but what I got after was clearly sharper than any of my other knives that were just shapened at 20 degrees without the 15 degree relief bevel.

-Steve

OK. It sounds like most of the difference is coming from the thinner geometry of the 15° primary (back bevel) behind the 20° microbevel, and that makes perfect sense all around. Less about the microbevel itself, or the methodology in applying it, and more about overall thinner geometry behind the edge, which should always improve cutting. I'd still maintain that it'll usually be easier to attain sharpness when applying a micro to a thinner primary, for the reasons I explained earlier (takes a minimum of passes to create a clean & crisp apex on a previously thinned primary). In general, very thinly-ground primaries are easier to sharpen for that reason, as it takes much less metal removal to get it there; therefore fewer passes and fewer chances for error.


David

 

[stevelenti]

OK. It sounds like most of the difference is coming from the thinner geometry of the 15° primary (back bevel) behind the 20° microbevel, and that makes perfect sense all around. Less about the microbevel itself, or the methodology in applying it, and more about overall thinner geometry behind the edge, which should always improve cutting. I'd still maintain that it'll usually be easier to attain sharpness when applying a micro to a thinner primary, for the reasons I explained earlier (takes a minimum of passes to create a clean & crisp apex on a previously thinned primary). In general, very thinly-ground primaries are easier to sharpen for that reason, as it takes much less metal removal to get it there; therefore fewer passes and fewer chances for error.

Right, but I think my original question got lost in the mix of things. Is there any advantages / disadvantages to just adding the micro bevel with a couple of strokes compared to adding a secondary bevel by working the burr and progressing up in grit? One disadvantage I can see to working the secondary bevel is you are removing more metal and it takes more time (though not very much in either case). Would the larger secondary bevel compared to a micro bevel have more edge retention? I would imagine the smaller micro bevel might be sharper, but that is just a guess ?? Both would be pretty easy to maintain with the micro lasting a bit longer between having to reset the back bevel. Stropping a larger secondary bevel might be easier because it would be easier to feel sliding on the leather. I'm making assumptions here of course so please correct me if I am wrong. As Brian mentioned, with a micro bevel you can add a toothy edge without affecting the look of the primary edge where as in my case you can see the secondary bevel so it wouldn't be as pretty.

The terms micro bevel and secondary bevel could be used interchangeably and maybe it just comes down to time and aesthetics. I am pretty happy with what I have accomplished so far with my knives but I love to know the "why" of things and always looking for new things to try.

-Steve

 

[Obsessed with Edges]

Right, but I think my original question got lost in the mix of things. Is there any advantages / disadvantages to just adding the micro bevel with a couple of strokes compared to adding a secondary bevel by working the burr and progressing up in grit? One disadvantage I can see to working the secondary bevel is you are removing more metal and it takes more time (though not very much in either case). Would the larger secondary bevel compared to a micro bevel have more edge retention? I would imagine the smaller micro bevel might be sharper, but that is just a guess ?? Both would be pretty easy to maintain with the micro lasting a bit longer between having to reset the back bevel. Stropping a larger secondary bevel might be easier because it would be easier to feel sliding on the leather. I'm making assumptions here of course so please correct me if I am wrong. As Brian mentioned, with a micro bevel you can add a toothy edge without affecting the look of the primary edge where as in my case you can see the secondary bevel so it wouldn't be as pretty.

The terms micro bevel and secondary bevel could be used interchangeably and maybe it just comes down to time and aesthetics. I am pretty happy with what I have accomplished so far with my knives but I love to know the "why" of things and always looking for new things to try.

-Steve

I personally believe that 'simpler is always better' with microbevels. The smaller the better; both from the aspect of creating it with a minimum of error, and in quickly maintaining or restoring it. I think a very small microbevel really needn't be stropped at all (save perhaps for a few passes on the jeans to clear very fine burrs away), as stropping usually justs increases the likelihood of over-finishing or rounding it off, and therefore defeating it's usefulness. If wanting to keep a microbevelled edge, I'd do it in such a way that it can be created and maintained or restored with just a few passes on the stone of choice, and nothing more. It's unlikely much improvement will be gained, in spending as much time & effort on the micro, as would be done on the primary bevels in the first place. Get the primary 'foundation' in good shape from the start, and everything following that should be much, much easier.

Stropping does work better on wider bevels though, as they're more self-stabilizing and less prone to rolling or pitching and rounding the apex. If I relied on stropping as the means by which I maintain my edges, I wouldn't use a microbevel at all (and I don't), for that reason. I'd gladly give up the tiny bit of extra durability afforded by a microbevel, in favor of much-easier maintenance of a wider bevel on a thinner edge. Maintenance becomes much, much easier when the edge's profile is conducive to it, as is the case with a wider and easier-to-stabilize bevel, both on stones and strops and any other means by which the edge will be maintained.


David

 

[stevelenti]

Thanks David. I normally use a strop to maintain my knives so this info helps and makes a lot of sense. Maybe I'll spend more time refining the primary and not worry myself with micro / secondary bevels.

Thanks again.

-Steve

 

[bucketstove]

The terms micro bevel and secondary bevel could be used interchangeably and maybe it just comes down to time and aesthetics.

My understanding is the micro bevel is the tip of the secondary bevel, the very apex.
They call it "micro bevel" because its microscopic, as in less than 20 microns , and can't be seen with the naked eye
It also makes sense to call it the "apex bevel" because its what forms the very apex.
The next bevel is the edge bevel because its connected to the apex.
in east its called primary, in the west its secondary
I think I like edge bevel because it describes what it is

 

[stevelenti]

My understanding is the micro bevel is the tip of the secondary bevel, the very apex.
They call it "micro bevel" because its microscopic, as in less than 20 microns , and can't be seen with the naked eye
It also makes sense to call it the "apex bevel" because its what forms the very apex.
The next bevel is the edge bevel because its connected to the apex.
in east its called primary, in the west its secondary
I think I like edge bevel because it describes what it is

Yeah, that confuses things even more. lol But I do like your idea of calling it the edge bevel. That makes a lot of sense.

In hind sight I should have kept the term "micro bevel" out of my original question because what I was more interested in the effectiveness of a "relief bevel" behind the "edge bevel". The reason for my statement above is by some terminology you could easily say that all micro bevels are secondary bevels. Which then you could state that all secondary bevels are not necessarily micro bevels.

-Steve