Longest razor edge holding steel on production knife?

[cuchulain77]

When you guys talk "holding a razors edge" are you talking days, weeks, months etc..? I find no matter what the steel is I'm sharpening frequently [assuming I'm actually using the knife].

I would say my M390 blades hold an edge much better than S30V or S35V.

 

[hank_rearden]

the first thing i'm going to say is: cutting up cardboard or rope without any noticeable change in bearing pressure from the knife hand is not a test for hair-shaving quality retention.

second, my control condition is the knife was sharpened shaving-sharp and just left on the shelf, or carried around without being used. the champions in my list are zdp-189 and vg-10. they split hair without fail even after lying around for more than 6 months. s30v, 1095, and d2 edges seem to "dry up" after lying around for a couple months.

 

[Boris74]

the first thing i'm going to say is: cutting up cardboard or rope without any noticeable change in bearing pressure from the knife hand is not a test for hair-shaving quality retention.

second, my control condition is the knife was sharpened shaving-sharp and just left on the shelf, or carried around without being used. the champions in my list are zdp-189 and vg-10. they split hair without fail even after lying around for more than 6 months. s30v, 1095, and d2 edges seem to "dry up" after lying around for a couple months.

It's a good thing you let them 1095, D2 and S30V blades just sit there. Just imagine trying to use one if they dull on their own. If you want the ultimate never dull after sitting around never being used blade you really need to ditch steel, that's so two centuries ago. You need a ceramic blade. With continued non use it will remain sharp forever and unlike steel, the edge will not evaporate. They are also a much higher level of shine and are lighter to carry all day not using it.

 

[Wolverine666]

the first thing i'm going to say is: cutting up cardboard or rope without any noticeable change in bearing pressure from the knife hand is not a test for hair-shaving quality retention.

second, my control condition is the knife was sharpened shaving-sharp and just left on the shelf, or carried around without being used. the champions in my list are zdp-189 and vg-10. they split hair without fail even after lying around for more than 6 months. s30v, 1095, and d2 edges seem to "dry up" after lying around for a couple months.

A sharp blade will actually become less sharp from just sitting in the drawer unused ?

 

[ejames13]

The grits on the SM are ~800 brown and ~1200 white? I use a 1200 DMT plate for most of my touch-ups as seen in the video. Your technique is sound, as long as you are holding an appropriate angle to sculpt the very apex, and a shaving-edge from either side indicates success :thumbup: But a wire-edge, depending on the foil created, can waver from side to side along the apex, it could be that you've created such an edge that crumbles or folds upon harder use than shaving *shrug* Are you using the points or the flats of the SM rods? If you finish by stropping on bare denim or leather or something similar to act simply as a "burr-catcher", that may help, but only if a folding edge is the problem *shrug*. Cardboard, especially thick stuff, is harsh and irregular, it'll squash a soft edge and fold a thin edge in a hurry. Here is an image from ToddS's blog showing the edge of an H1-steel blade at 20-dps after cutting 20' of thick cardboard: https://scienceofsharp.wordpress.com/2015/01/13/what-is-a-burr-part-2/

Before:

After:

That's an awesome blog! Now I have reading material for the next few days

I always use the flats on my sharpmaker. I had no idea edge geometry was so complex. I always thought you wanted to raise a burr during sharpening, but looks like he's saying it's better not to. Or if you do, you have to eventually eliminate it to get back to the actual apex and then ensure it is sharp after removing the burr.

 

[Jason B.]

That's an awesome blog! Now I have reading material for the next few days

I always use the flats on my sharpmaker. I had no idea edge geometry was so complex. I always thought you wanted to raise a burr during sharpening, but looks like he's saying it's better not to. Or if you do, you have to eventually eliminate it to get back to the actual apex and then ensure it is sharp after removing the burr.

I wouldn't believe everything I read on the Internet. I find it funny those who talk about not forming a burr, why?, because it would only be possible in gods hands. If you have an apex then you have a burr, it's just how it works.

 

[Ankerson]

I wouldn't believe everything I read on the Internet. I find it funny those who talk about not forming a burr, why?, because it would only be possible in gods hands. If you have an apex then you have a burr, it's just how it works.

Exactly correct. :thumbup:

 

[ejames13]

I wouldn't believe everything I read on the Internet. I find it funny those who talk about not forming a burr, why?, because it would only be possible in gods hands. If you have an apex then you have a burr, it's just how it works.

So how do you eliminate said burr and still wind up with a keen/sharp apex?

 

[Jason B.]

So how do you eliminate said burr and still wind up with a keen/sharp apex?

Light pressure reduces burr size to a point were it no longer matters or it can be stripped off with leather and compound. Burrs are deformations of metal related to the sharpening pressure applied, more pressure= more burr, less pressure= less burr. It's not all that hard to use just a stone to create a sharp edge, you just have to understand the process.

 

[chiral.grolim]

That's an awesome blog! Now I have reading material for the next few days

I always use the flats on my sharpmaker. I had no idea edge geometry was so complex. I always thought you wanted to raise a burr during sharpening, but looks like he's saying it's better not to. Or if you do, you have to eventually eliminate it to get back to the actual apex and then ensure it is sharp after removing the burr.

Good job using the flats :thumbup:

You can avoid a burr by sharpening behind the apex at a low enough angle (edge-leading) to thin the material and only ever micro-chip away the apex: https://scienceofsharp.wordpress.com/2014/04/16/the-honing-progression/

The edge is thin but rough/toothy... which is actually great for cutting cardboard and rope :thumbup: No detectable burr.

But if you don't raise a burr, you haven't really sculpted the apex, only thinned the blade material behind it. In apex sharpening you cannot avoid raising a burr, as Jason B. stated and as is mentioned in the blog:

This foil-edge burr can be reduced, but not eliminated ... Fortunately, this foil is fragile enough to be completely removed by a few strokes of beard shaving and the edge width after breaking off the burr is well below the threshold for comfortable and efficient shaving...

Fresh off the stone before stropping:

After stropping 10X on 0.25-micron loaded leather:

The stropping is what creates the burr as the abrasives sculpt the apex. But after 100 laps, the foil is reduced to a manageable size (note the scale) that will break-off to a keen edge rather than fold-over and thicken the edge:

ToddS does warn against stopping on bare linen as it can apparently pull off more material than desired, breaking the apex to a thicker diameter? *shrug*
Keep in mind that he his honing razor blades to MUCH higher grit and lower angles. At 20-dps, there is a lot more supporting material to prevent the apex from being torn away stropping.

 

[ToddS]

The grits on the SM are ~800 brown and ~1200 white? I use a 1200 DMT plate for most of my touch-ups as seen in the video. Your technique is sound, as long as you are holding an appropriate angle to sculpt the very apex, and a shaving-edge from either side indicates success :thumbup: But a wire-edge, depending on the foil created, can waver from side to side along the apex, it could be that you've created such an edge that crumbles or folds upon harder use than shaving *shrug* Are you using the points or the flats of the SM rods? If you finish by stropping on bare denim or leather or something similar to act simply as a "burr-catcher", that may help, but only if a folding edge is the problem *shrug*. Cardboard, especially thick stuff, is harsh and irregular, it'll squash a soft edge and fold a thin edge in a hurry. Here is an image from ToddS's blog showing the edge of an H1-steel blade at 20-dps after cutting 20' of thick cardboard: https://scienceofsharp.wordpress.com/2015/01/13/what-is-a-burr-part-2/

...

Those images are a poor example - that "double cardboard" was mostly glue.

Here is a manbug in ZDP189, as honed - shaves easily, catches arm hair, push cuts paper effortlessly (no burr, obviously):

After about 1 meter of normal corrugated cardboard, the edge is starting to damage in discrete locations. Shill shaves and somewhat push-cuts paper, draw-cuts well.

After about 5m of normal corrugated cardboard, no longer shaves or push-cuts. draw cuts paper roughly.

 

[marsalla]

Thoses are awesome pictures; very informative. so you would recomend a stopping compound.

 

[chiral.grolim]

Those images are a poor example - that "double cardboard" was mostly glue.

Here is a manbug in ZDP189, as honed - shaves easily, catches arm hair, push cuts paper effortlessly (no burr, obviously)...

What kind of guy just sits and looks at images like these to unwind? *sigh* Always appreciated, ToddS :thumbup:


Have you got any running the same test on a different steel (probably different hardness as well) with same geometry? Any difference in damage "profile"?

 

[me2]

Hey Todd. Can you elaborate on what you mean by "still shaves?" Do you mean face shaving, arm shaving, or other?

 

[ToddS]

Hey Todd. Can you elaborate on what you mean by "still shaves?" Do you mean face shaving, arm shaving, or other?

I mean it the "knife-guy" sense, that it will remove arm hair. This blade is not nearly keen enough to shave my face.

What kind of guy just sits and looks at images like these to unwind? *sigh* Always appreciated, ToddS :thumbup:


Have you got any running the same test on a different steel (probably different hardness as well) with same geometry? Any difference in damage "profile"?

Not something I have looked at in any detail. I need to find some more 2-inch folders that are easily disassembled, in different steels.

Thoses are awesome pictures; very informative. so you would recomend a stopping compound.

I generally strop my pocket knives - the two knives shown above were stropped on 0.25 diamond.