Problem sharpening an Aus8 blade

M

maximus83

Joined
Nov 7, 2011
Messages
2,104
This is probably due to my inexperience at working with Aus8, but I am having a problem with getting the blade a sharp as my other blades. I sharpened and sharpened this thing tonight, ordinarily I have no problem getting my VG10, S30v, S35v, 1085, and SR101 blades hair-popping sharp. But the best edge I could get on this blade (it was a SOG Pentagon Elite 1), it wouldn't even shave arm hair. This was after many many passes on a Spyderco set including the diamond rods, the carbide rods, the fine ceramic rods, and the extra fine. It has a nice LOOKING 20 degree beveled edge, but it just isn't very sharp.

Any tips? Do I just need to lower my expectations for how good of an edge I can get on an Aus8 blade?
 
I've never had much luck with aus 8 either. I think it's because I'm impatient and don't take enough time with each grit.
 
I have no problems. I normally use a strop or some cardboard box material to polish the edge.

So, my only input: It can be made sharp, try with a strop.
 
Last edited:
Have you really reached the full apex? If not, no point going to finer grit nor stroppong woul help.

A larger blade might take longer, especially if your angle is thinner than original. My Navy k631 has about 40-50 inclusive, and I like my angle shallower. It took me 2 weeks of free hand sharpening over many sessions to fully apexed it to be 20-30 inclusive.
 
Aus8 is one of the more forgiving steels IMHO - it can accept just about any edge from coarse to fine and turn out easily sharp enough to shave arm hair and beyond. I second the possibility you might not be getting all the way to the apex - use a Sharpie. I sharpened up a buddy's Aegis tanto to a shaving edge with just a couple of old bench stones. I was surprised at how obtuse the factory grind was - 45 or 50 degrees (inclusive).
 
+1 to what hh said. follow his directions and you should get it. if you have problems i'll be glad to give you a call and help you out.
 
I'll add a 'ditto' to making sure the apex has been reached. Look for the burr formation, then very gently remove it with the finer hones. My habit is to use a decent magnifier & bright light, to closely look for it (as opposed to relying solely on the Sharpie ink). AUS-8 can get scary, wicked sharp. As mentioned, it takes a variety of edge finishes very well, from coarse to highly polished. Way back when I first started collecting knives, I think AUS-8 was the first steel that 'imprinted' the concept of 'Scary Sharp' in my brain. I'd seen and/or bought some Japanese-made knives with AUS-8 blades, and those were the first ones I'd seen that I knew I had to be careful with. They had some relatively coarse edges on them, with a lot of scary bite. Depending on the RC hardness, some of the 'softer' ones might need some gentler handling with the hones. It sharpens up very easily, and it's sometimes easy to overrun the burr formation, which is the indicator that the edge has been apexed. If you miss it when it happens, you might end up overdoing it with the hones and erasing the burr before you see it (easy to do, with diamond hones especially).
 
Can somebody explain the "apex" thing to me a bit more? Not sure if I understand what the goal is there, and how I'd achieve it.

Also, besides the "arm hair test," what are some better, and more objective tests for sharpness?

One other thing: I went with a 40 degree inclusive angle on the Sharpmaker. Would I be better off going to the 30? With most of my EDC and folders, I stick with a 40-degree inclusive, knowing that it gives up a bit in fine slicing ability, but also gives a somewhat stronger, longer-lasting edge. For me, the 40 degree is good enough in other steels for EDC, but wondering if with Aus8, maybe I should go to 30.
 
Last edited:
I think by apex they are saying do the two sides of the edge meet as refined as you would like.

That is the goal no matter the method you use. If the angle on the edge doesn't match the angle on the sharpmaker you will just be grinding on the shoulder. Jou need to be removing material from the face of the edge bevel on both sides so that when you are done they meet. If they do not meet then no attempts at refining the edge with finer stones and such will help.

As far as testing I do not worry about the method. I just make sure I use the same method for all of my blades. I keep a legal pad in my sharpening kit. I test before, sometimes during, and after sharpening. I use the same paper for all my testing. I know how my blades slice and cut when dull and how that correlates to my chosen test media. I know how they slice and dice when I have sharpened them and I know how my sharpening work feels slicing through the same paper.
 
maximus83 said:
Can somebody explain the "apex" thing to me a bit more? Not sure if I understand what the goal is there, and how I'd achieve it.

Also, besides the "arm hair test," what are some better, and more objective tests for sharpness?

One other thing: I went with a 40 degree inclusive angle on the Sharpmaker. Would I be better off going to the 30? With most of my EDC and folders, I stick with a 40-degree inclusive, knowing that it gives up a bit in fine slicing ability, but also gives a somewhat stronger, longer-lasting edge. For me, the 40 degree is good enough in other steels for EDC, but wondering if with Aus8, maybe I should go to 30.
Click to expand...

My own preference would be to go with 30 degrees, but that's purely a preference thing. If you do that, you can still apply a microbevel with the 40 degree setting, or simply maintain on the 30 side. With a microbevel, you'd still gain some in edge durability, and the 30 degree 'shoulders' of the back bevel would still improve fine slicing ability.

The 'apex' concept refers to the straight lines of the bevels on each side intersecting at the edge as cleanly and perfectly as you can make it. Stopping short of the apex implies that the edge would still be somewhat blunt or rounded or otherwise less-than-sharp.

For testing edges, I like to check slicing ability in phone book paper. Slice into the paper, along the full length of the edge, from heel to tip. If the paper snags or slips, that's an indicator of problems areas on the edge, like burrs or wire edges (which would snag the paper), or just being a little blunt (paper slipping without cutting). I've found that when I can slice cleanly and repeatedly, using the full length of the edge, that's a good indicator of a healthy, durable working edge. I don't rely too much on shaving or hair-popping/whittling/etc as truly indicative of the durability of the edge. Wire edges can shave easily, but fold over quickly under almost any other cutting chores. That's not to say a good edge can't shave, but it doesn't necessarily have to, to be a good working edge for virtually all tasks. It is fun and satisfying, however, to produce a hair-popping edge that lasts.
 
I have no idea how SOGs AUS8 performs, I will say with the AUS8 from Boker and ColdSteel that I've sharpened, it takes a very fine edge, and touches up very easily. My guess is it's a bit softer and the last bit of time you spend sharpening it, just take your time and be lighter in your hands.
 
Max, the thing to remember Aus 8 is a lot softer than those steels you sharpened.
Using a stone too coarse can over sharpen the knife causing the edge to bend a tad

You can feel it with your fingers. Gently rub edge one way then the other
It will feel blunt one side and sharp the other if over sharpened

As Obsessed mentioned sharpen under a bright light and see if any light reflects off the edge
I only use a medium grain stone to sharpen then a fine stone to hone Until no light reflects of the edge

Also the sharper your edge gets the slower and softer you need to move. When its almost razer sharp
gently hone both sides of the edge with a fine stone

I've gotten it razer sharp to shave my arm hairs at 30 degrees.

With me it was the opposite. Got a Zero Tolerance ZT 0200 ST and sharpened gently as I'm use to
with my crkt knives and wondered why I was taking forever to sharpen.
 
I'm getting so torqued off with this blade I'm about ready to snap it in half. Spent nearly 2 hours with it today: tried a large coarse DMT bench stone (reprofiling), then tried a BUNCH of Sharpmaker time, going from diamond rods, to carbide, to ceramic fine, to ceramic ultrafine, then stropping. Also changed the angle to 30 degrees inclusive. Slightly better due to blade angle, but same basic issue: blade will not shave arm hair or stand up to my other blades in sharpeness comparisons.

I think this SOG is either a POS, or perhaps Aus8 just can't be gotten that sharp. I can't believe that I'm doing something wrong on this blade when I don't have issues with any of my others. But I'm open to suggestions.
 
Obsessed with Edges said:
For testing edges, I like to check slicing ability in phone book paper. Slice into the paper, along the full length of the edge, from heel to tip. If the paper snags or slips, that's an indicator of problems areas on the edge, like burrs or wire edges (which would snag the paper), or just being a little blunt (paper slipping without cutting). I've found that when I can slice cleanly and repeatedly, using the full length of the edge, that's a good indicator of a healthy, durable working edge.
Click to expand...

Using this test, my edge appears to be doing ok. But my other tests (the hair shaving test, and the pen test), this knife seems to fail. For instance, doing a really simple test, I picked up a little candy wrapper, pulled out my EDC (a Benchmade with s30v blade that I get really sharp), and holding the little wrapper up, with the BM I can just lightly slice on the edge and it cuts in. With the SOG, I can slide HARD and it won't sink in, I have to stab. It'll cut paper ok, but it's clearly nowhere near the BM even after a TON of sharpening effort, and pretty much the same appraoch I use with all my other knives.
 
Last edited:
Finally made some headway. Here's what I did differently. Don't know if it was the cumulative effects of all the sharpening, or if trying something different, worked.

I used a DMT diafold coarse/fine sharpener. I freehanded the blade with it, put a sharpie on the blade to ensure I was getting to the apex and getting a flat, consistent edge and angle. I was. Worked it over for a good while coarse and fine side, then stropped.

Now, it'll cut a little bit of arm hair. It'll do the vertical cuts on paper and candy wrappers, plus it passes the pen test. So, I think it's getting there.

Starting to wonder if the Sharpmaker actually holds you back and makes things take longer. It appeared that I made more headway by freehanding it today.
 
Good news!

Can't comment on sharpmaker, as I always free hand sharpen them :D

Seems that the original problem was not fully apexing it IMO ;)
 
can't comment on the sharpmake either but i can comment on ceramics on "softish" steels ... that's a no no for me, too hard, they tend to create problematic wire edge if you use anything more than a feather touch.
 
pwet said:
can't comment on the sharpmake either but i can comment on ceramics on "softish" steels ... that's a no no for me, too hard, they tend to create problematic wire edge if you use anything more than a feather touch.
Click to expand...

+1

It's taken a long time for me to re-calibrate my 'touch' on ceramics and diamond hones. Either one will create problems (albeit different ones), if pressure is heavy. As mentioned, ceramics will create wire edges on more 'ductile' steels like AUS-8, 420HC, VG-10, ATS-34. Wires on the latter three can be an absolute PITA to remove (that's the ONE thing I really dislike about VG-10, and ATS-34). Some other steels that are heat-treated to relatively low RC can be a challenge on ceramics too (Victorinox's stainless comes to mind, as well as the softish 440C in Boker's traditional knives). All too easy to create & erase a burr without noticing it, which then results in much more metal removal than is necessary. Diamond hones will do the same on all but the most abrasion-resistant steels, so you really have to pay attention to what's happening at the edge after each and every stroke.
 
Sheesh, I had no idea how involved it would be when I started getting serious about sharpening my stuff better. I kinda' progressed from crappy old sharpening stone, to Sharpmaker, to now freehanding with DMT bench stones. But it seems like there's a lot of ways you can slip up. I really hadn't learned to adjust my pressure for different metal types yet; I guess up to now, I've been getting lucky as all my blades are either in a very hard steel (s30v/s35v) so no worries about pressure, or in plain carbon steel so hard to go wrong when sharpening.

This was my first attempt to get a "soft" stainless really sharp. I have to think you guys were right: either I was pushing too hard at first, or the ceramics on the Aus8 were bad, or I didn't have the apex right. Or some combination of those things.
 
Made further improvements in it tonight. Now, this thing is finally INCREDIBLY, hair-popping sharp. As many people said, it was a matter of learning to work differently with the Aus8 steel.

Here's the sequence I used that finally got it extremely sharp, sharp enough to slice vertically through notebook paper with no pressure and to shave arm hair with only a light touch.

1. About 20 strokes each side of blade on my DMT extra-course bench stone. I profiled the bevel to about 30 degrees inclusive. Heavy pressure at first, lighter toward the end.

2. About 30 strokes each side on the course side of the DMT. Moderate pressure, moving toward lighter at the end.

3. About 10 strokes each side on the gray carbide stones on the sharpmaker. Very light pressure.

4. About 10 strokes each side with the standard fine white ceramic stones. Very light pressure.

5. Stropped on a leather paddle using Flitz on one side, plain leather on the other.

This whole sequence took about 25 minutes, and that was even with me experimenting and adjusting my freehand strokes on the bench stone. Really, the coarse DMT stones speed things up and are a worthy complement to the sharpmaker. The sharpmaker is great for REFINING an edge, the DMT stones are great for CREATING an edge (or fixing it) in the first place.
 
You must log in or register to reply here.
Back
Top