Defining, Testing and Achieving "Sharp Enough"

[coote]

I started using blades long before I started to think deeply about what 'sharp' was. Coming to this forum has probably had a lot to do with the way I waste so much time now thinking about achieving a good edge... ... but this is where I'm at now:

Definition of sharp enough. Will perform the task required with relative ease. Nowadays I like to get arm-hair shaving sharp if I can, but it isn't always necessary.

Testing Sharpness. Hair shaving down my arm 'with the grain' is what I have done alot. Nowadays I'm often content to just slide the blade sideways over my thumb or finger nail. If the blade grabs the nail rather than just slide over it, I reckon it is probably sharp enough for general needs. Slicing a sheet of paper held vertically is something else I might do to impress bystanders. Looking closely at the edge in bright light might show some shiny parts on the edge.... these are likely to be the blunter parts.

Achieving Sharpness. A good mill file might be all that is needed for all sorts of blades. Certainly I would use a file for machetes, axes and slashers (brush hooks).... although I've found some axes and slashers to be a bit too hard to file successfully. After I've used the file I might wipe an oilstone down the edge a few times.

If I want to change the angle of an edge, or sharpen a really blunt blade I might use an electric grinder (or belt sander if available). I even use a cheap disk grinder sometimes. No matter what I use, I take care to not overheat the blade. A file might then follow the grinder, then a whetstone, then maybe a sharpening steel.

My dad used to sharpen a knife by using a whetstone with a circular motion. That certainly worked well enough and that is what I did too. Nowadays I might just drag the blade 'backwards' over a stone if it is not perfectly flat and smooth. By going forwards with the blade I feel that the edge can dig in and get damaged if the stone isn't perfect.

For getting a final edge on a knife, or simply touching it up, I had great success with a Tri Angle Sharpmaker. But I don't have one of these any more, and really it wasn't totally necessary. But I might get another one day if I have some discretionary money in the toy account.

If I had to pick just one sharpening tool to finish an edge, it would be a large, medium grit Arkansas stone. If I could have two, it would be the stone and a decent steel. This pair are what I am used to. They will achieve shaving sharp in a fairly short time.

In the field I might carry a small carborundum stone, a short file, or a short ceramic rod. More recently I've obtained a cheap retractable diamond sharpener which certainly will restore an edge. A lot of guys used to carry a short steel on their sheaths, but they are heavy and won't work that well to get a 'ding' out of the blade.

 

[August West]

Afraid I am a bit OC about my edges, there is no such thing as sharp enough, when one of my knives cuts something by getting close to it, it might be sharp enough. If my knives won't readily shave arm hair I sharpen them. I use almost exclusively spyderco ceramic bench stones and a spyderco double stuff pocket stone. After sharpening on the stones I strop with a piece of leather and polishing paste. I have a small mora setting beside me now that will readily clip a hanging hair, I honestly believe I could lather up and shave with it.

I do not mind using my knives, but will touch them up often when I notice cutting performance declining. I carry a pocket stone and strop virtually everywhere I go, like I said I am a bit obsessed. Chris

 

[De4thStr1ke]

Afraid I am a bit OC about my edges, there is no such thing as sharp enough, when one of my knives cuts something by getting close to it, it might be sharp enough. If my knives won't readily shave arm hair I sharpen them. I use almost exclusively spyderco ceramic bench stones and a spyderco double stuff pocket stone. After sharpening on the stones I strop with a piece of leather and polishing paste. I have a small mora setting beside me now that will readily clip a hanging hair, I honestly believe I could lather up and shave with it.

I do not mind using my knives, but will touch them up often when I notice cutting performance declining. I carry a pocket stone and strop virtually everywhere I go, like I said I am a bit obsessed. Chris

Same here, "sharp enough" isn't in my vocabulary. My friends always get mad at me when they play with one of my knives, they'll say something like "Man, this thing is a razor!" and I'll always comment on the fact that I think I can make it sharper. I seriously think it's an addiction!

As for what I use, I love the SharpMaker, it's so quick and easy to use. But for harder tasks I have some various stones (steel and otherwise) that I've gotten over the years. And if a blade has been really killed I have a small chainsaw grinder that'll whip it back to shape in no time flat.

 

[Rotte]

Nowadays I'm often content to just slide the blade sideways over my thumb or finger nail. If the blade grabs the nail rather than just slide over it, I reckon it is probably sharp enough for general needs. Slicing a sheet of paper held vertically is something else I might do to impress bystanders.

My grandfather taught me to check the edge with a sideways slide over my thumbnail. If it worked for him it should work for me.

Should.

I like the newspaper test. If it cuts free-hanging paper without micro tearing, it's sharp enough. Any hint of resistance or tearing and it's back to the strop.

In the end, it's really a question of whether or not the tool does the job well. So I think we can become too obsessed with a "razor edge."

Did I just say that out loud? :foot:

 

[Bolt-action bultema]

I shave with a straight razor, since I started, the razor's edge has been my benchmark. If I haven't shaved with a knife, I don't feel truly satisfied with the edge. I just got my Kabar heavy bowie sharp enough after re-profiling the edge, an boy was that an awkward shave. I am working up the courage to use my GB small forest axe, but I just haven't had the balls yet.

 

[ksquared]

So whats the trick to stropping? I get my knives arm-shaving-sharp with an X-fine Dia-Sharp diamond (1200 grit) but I know they can be sharper. My experiments with stropping, using an old leather belt and polishing compound from the box store have proven unsuccessful. Any thoughts?

 

[Rotte]

It might depend on how thick/soft the belt is. I like thin and firm leather for a strop.

Load the strop with compound. Keep the strop on a hard flat surface. Clamp it if you need to prevent it from sliding around. Keep light pressure on the edge as you draw the blade back. Don't angle the knife too high--the blade will deform the strop as you pull against it, and it can actually wrap up and dull the edge if you use to much pressure or too high an angle.

Those are my thoughts.

 

[ksquared]

Thanks- I does seem as though I manage to dull the blade as I go. I'll try the shallower angle.

 

[Rotte]

Thanks- I does seem as though I manage to dull the blade as I go. I'll try the shallower angle.

What kind of edge are you sharpening? I should have asked that first.

 

[Bolt-action bultema]

I like to use scraps from tooling leather that I have around, and I just leave the remnants from the oilstone on the blade as a polishing compound.

The biggest lesson I learned about stropping, is to keep the blade at the same angle the entire time. A long arm movement tends to roll the edge at the end, and dulls rather than polishes the edge, so short, controlled strokes work best for me.

Rotte is right on the money as well, listen to him.

 

[fujita yuji]

My definition of sharp enough is to shave my face after sharpening.

To see whether go sharpening or not, I see the edge under direct sunlight
as said in the OP.
I go sharpening if I see bright spot on particularly important part of the edge
for example around bottom, within the berry or near the point.

I strop the edge once a week and go benchstone once every two months.

 

[warrigal]

My standard, fillet a piece of photocopy paper.

Buck 136 excellent if you can find one ( don't bother asking Buck)

My strop. Old Sam Brown belt, Autosol metal polish. ( CS Gunsite for size)

Me
http://www.youtube.com/watch?v=6yVN9lLVPM4
Carl

 

[Stormstaff]

One of these days I really need to start practicing my sharpening skills.

 

[August West]

One of these days I really need to start practicing my sharpening skills.

Owning a knife and not knowing how to sharpen it is like driving a car a not knowing how to put gas in it.

Go to wally world or any big box store and buy the cheapest made in china knife you can find, make sure it is a sporting knife not a kictchen knife. Then buy some cheap arkansas stones and start sharpening, when you can get that knife to shave your good to go. Chris

 

[dawsonbob]

I think I've gone through several stages regarding blade sharpness.

When I was a little kid with my first blades, I didn't know the difference. When it got too difficult to push the blade through whatever I was trying to cut, I would give it to my dad who would "make it better."

I watched my dad sharpen knives, and thought I understood what he was doing (I didn't really). I took over sharpening my own knives and, after awhile, I could get them sharper than when I started, but not as sharp as my dad could. I didn't know why: after all, I was doing the same things as he was, right? I was too stupid — or too young — to break down and ask what I was doing wrong.

As the years went on, I got to the point that I could get a knife to shave arm hair (I'd grown some by then)... in one direction, with one side of the blade. The other side of the blade wouldn't even come close; in fact, it felt dull. I had no idea what a burr was.

Later — I won't say how much later, because it would show what a slow learner I was — I started taking it seriously: seriously enough to read and ask questions. Burr? Oh, that's what that is, huh? You need to get rid of that, huh? Amazing.

Eventually, I invested in better stones and, gasp, discovered the strop. Wow: what a difference! Being an OC type, I dove in wholeheartedly, and worked at it until I could get an edge to shave molecules. Triumph, at last!

By the time I got to the point that I could get a blade that sharp, I realized that I didn't need to make every blade that sharp. Yeah, it was fun — and good for my little ego — but it wasn't really necessary. With some blades it was even the wrong thing to do: some actually cut better with a rougher edge.

Now I believe that sharp is being able to cut what you want to cut, the way you want to cut it. No more, no less. I have one machete that sees a mill bastard file and maybe a rough stone if I'm feeling like it, but that's all: it cuts fine for its uses. I have another machete that I lovingly convexed, and I could shave with that one (if I were really, really stupid). The rest of my blades will certainly shave arm hair, but that's about it. Okay, okay, sometimes the silliness creeps in on me, and I have to see just how sharp I can get an edge. Why? No reason, really, other than it's still fun to do. I have no idea how much time I've spent in my life trying to get a perfect edge when it wasn't strictly necessary. Time wasted? Nope: I enjoyed every minute.

Bob "Not the sharpest, just sharp enough" Dawson

 

[warrigal]

Sorry about the earileir post it was the end of the day.
Dawson you have hit the nail on the head several times.
Self taught can be a very very long road.
Right degree of sharpness for the tool and the job.
And it is a dying art don't be afraid to get some help.
Carl

 

[John G]

I wonder, is it possible to over strop an edge? I've had edges with a mirror polish that don't cut nearly as well as from the factory.

 

[DH1]

I test my blades by holding a sheet of paper and seeing if I can slice it easily. If it hangs up on the sheet at any point, there's usually a tiny bump on the edge that I strop out. Shaving arm hair is also a test I'll do.

Overall I don't get too insane over how sharp an edge is. Any blade I carry is plenty sharp, but they won't slice a hair down the middle.

 

[greenwoods]

Ya know Coote ,ole' bud, you've got me thinking about all my blades
They are, all of them, part of an ongoing project. I've neckers, fixed hunters, skinners, big blades, choppers, hawks, throwers, stilettos, stabbers, swords...ad infinitum(jk ).

And now for something completely different...
...My khuks all have similar edge geometries, so they can do ALL of the jobs I need them to. My Nessies have skinning and some chopping and some fuzzy stick making edge's, My Moras all have excellent woodcraft edges and COULD be shaving sharp, yet wouldn't last so long in their carving sharpness stage. Straight razors, well...they...RAZE...

So I find that many knives can do much, some can do special and any can be made to do most, what do we want?

And kudos for the Grampas that sharpened most with a circular expertise on a plain gray stone:thumbup:
He was right on!

Mark

 

[dawsonbob]

I wonder, is it possible to over strop an edge? I've had edges with a mirror polish that don't cut nearly as well as from the factory.

Can you over-strop an edge? Nope, but just like in sharpening, you can have the wrong angle, or be putting too much pressure on your blade while you're stropping. If you do put too much pressure on the blade, or hold it at the wrong angle, you can actually round the edge, which dulls it.

What you want to do, is lay the blade on the strop at a very, very shallow angle and — using not much more pressure than the weight of the blade — strop it from the back (spine) of the blade to the edge. It take some practice, but you'll get it.

Remember that the leather of your strop has some give to it, much like a mouse pad, and will wrap around the edge if you're not careful. I would suggest the old marker trick for the first few times you strop, until you get the hang of it.

Hope that helps. If you want to learn more, go to the Maintenance and Tinkering section, and look for threads on stropping. Some of those guys are really into it, and provide some detailed instructions.