From the Old Fart files

[hollowdweller]

I usually don't sharpen my convex edges with the blade flat. I usually use a mousepad or adjustable tension strop and have a slight angle. The sandpaper follows the convex shape without scratching up the blade.

 

[Abe]

Take the knife in need of sharpening and lay it flat or nearly flat on the hone. Move the knife in small semi-circles over the hone until a burr pops up (assuming you have a knife with steel that easily burrs - that should be 98-300% of your collection). Flip over and repeat. Do a few light, alternating passes over the hone at a slightly higher angle to remove the burr.

Just a quick clarification request:

"Move the knife in small semi-circles over the hone until a burr pops up "

Does this mean the semi circles are made completely in the horizontal plane ie with the blade always flat to the stone, or that they are in a vertical plane ie described by the spine lifting up from the stone in an arc in a straight stropping-like motion?

I assume it's the latter

 

[Cliff Stamp]

Does this mean the semi circles are made completely in the horizontal plane ie with the blade always flat to the stone, or that they are in a vertical plane ie described by the spine lifting up from the stone in an arc in a straight stropping-like motion?

It depends on the knife. Some are sharpened flat to the stone so the spine gets abraded with the edge and the light convexity in the edge is induced by the wear in the stone and the natural slop of the user. Depending on the stone this is slight and changes the angle by maybe 1-2 degrees from the shoulder to the very edge. On knives meant for harsher cutting then you want a more abrupt angle so the blade is lifted lightly off the stone. If you want a really heavy convex bevel so the angle changes enough you can see it curve in from the shoulder to the very edge then you need to actually focus on rotating the stone or blade to induce the curvature. It isn't as hard as it may sound. Fikes demonstrates his method in his video and he uses a huge diamond stone freehand with the blade slowly rotating in his off hand.

-Cliff

 

[Abe]

Thanks, Cliff.
So by way of illustration, if I was to try this with, say a flat ground kitchen knife with a 15 degree secondary bevel, I would place the blade flat on it's primary grind and hone away in flat semi circles until the secondary bevel disappears and a slightly convexed full grind (spine to edge) was left?
Quite a bit more time required than the original post suggests, then.
Or, I could make life easier by drawing the blade staight back on the stone (no semi circles) but rotating the spine upwards away from the stone, though resulting in a more obtuse edge?
Is the Fikes video somewhere on this forum?
Thanks for your patience

 

[kel_aa]

Even on users, I would still say looks can still be important. For instance, if you were asked to sharpen someone's user Benchmade AFCK, and in your liberty you decided to raise the grind, apply a hollow relief, and it ended up looking like this:

doesn't it sort of defeat the purpose of buying an AFCK (which I think is very gorgeous, by the way)? Try to tell them about the 850% performance increase in slicing cardboard while they are choking your eyeballs out. They might as well asked you to grind them something out of a file or saw.

Originally Posted by Cliff:

A 15 degree edge for example is easily strong enough on even a decent steel to chop up caribou legs with no visible damage, this is obviously way overkill for a utility knife made to cut things.

Does this apply to decent stainless steels too? If it is so, then my sharpening must be very bad. If the steel is nicer, I guess I can get away with a half-decent edge. On the Aus8 Kershaw Antelope Hunter I reviewed here, I recently deboned 4 chicken quarters and cut up the meat on a plastic tray, and the edge was reflecting light at many places. And I would say Kershaw Aus8 is fairly crisp (Benchmade 440C being the most crisp steel in my experience), although it can roll a bit on some of the ones which I imagine are softer (Cold Steel Aus8). I have the hardest time sharpening the ATS-34 in the AFCK. I feel the grain is coarser than many others. I can end up with a functional edge, but I get reflective spots where I feel I should not sooner than I expect. I really do notice how much more abrasion resistant it is from sharpening it. I also get the impression that it is fairly ductile (opposed to crisp. I guess by crisp, I mean no burr/wire edge or movement of the steel at the edge). Any ideas?

 

[db]

The type of stroke you use doesn't really matter some do circles and I personally go back and forth like scrubbing. Keeping the spine down on or close to the hone is what matters. As for the finish and scratching the side of the blade, who says you have to stop at the coarse hone? You can put any type of finish on the sides that you want and I've made some old knives look alot better this way. Made alot of new ones look better too for that matter.

 

[sodak]

Thom and Cliff,

Could you describe the circles to me? I'm having a hard time understanding why this would produce a convex edge. It seems to me that it would give a real nice thin v-grind. When you say move it in circles, are they circles from a bird's eye view, or semi-circles as if you are scooping ice cream?

Inquiring minds want to know! Thanks!

 

[thombrogan]

Could you describe the circles to me? I'm having a hard time understanding why this would produce a convex edge. It seems to me that it would give a real nice thin v-grind.

More semi-circles like scooping ice-cream. Not as fast or efficient as the methods used by db and Jimmy Fikes (two different methods), but designed to take advantage of tissue compression and imperfect motor skills and still give you a very sharp knife with a convexed edge.

kel_aa,

I agree that user knives should look good, too. A knife with an edge that handles a 16-20 degree back-bevel with a 22-24 degree edge (11-12 degrees per side) looks incredible. A knife that handles a lower edge looks better. I have a blade blank Alvin Johnston gave me that I hollow-ground so it'd sharpen flat on anything in no time flat and few knives look better.

 

[kel_aa]

I'm not necesarily saying they should look good. But looking decent can certainly be an important criterion. With some of the knives out there, you aren't buying pure performance anymore. Have you seen the later pictures of Cliff's Sebenza? From those pictures alone, I might suspect that Cliff pulled a piece of scrap metal from a pool of corrosive slag, ground it on the sidewalk, and then mounted it into the handle.

 

[bbcmat]

Here is a visual - Cliff loaned that Sebenza to a partner that gave the edge a quick freshen ON A SHINGLE - hey yooooooooooooo!!!!

MAT

 

[Cliff Stamp]

I'm having a hard time understanding why this would produce a convex edge.

When Alvin speaks of his knives having a convex edge it just means the edge isn't jig sharpened to a highly uniform v-bevel. As you hand sharpen there is variance in angle and this will produce a varying bevel as Thom noted. The type of abrasive will influence it because soft ones which wear rapidly will form a significant convex bevel as they dish. The really coarse waterstones can wear in so fast that on just one sharpening they will induce a curvature of 1-2 degrees per side.

If the edge bevel has a deeper curvature where you can actually see it roll from the shoulder to the edge you need to induce a curvature so you have to rotate either the blade or the stone or use an abrasive which will give and match the curvature. The most efficient method I have found to date is the modified Fikes approach which I described recently. This allows me to sharpen a large (7-10") chopping blade in a decente steel from the point where it won't slice paper to push cutting in just a few minutes :

http://www.bladeforums.com/forums/showthread.php?p=3770814#post3770814

Try to tell them about the 850% performance increase in slicing cardboard while they are choking your eyeballs out.

It depends a lot on the perspective of the user. The vast majority of knives I sharpen are for people who see them as tools, similar to a hammer. When I sharpen most knives for others the first thing I do it lay them on the slack region above the platen and grind them flat to the belt. This will produce an edge about eight degrees per side and it hits the primary as well. I then clean up the edge with a 200 silicon carbide waterstone which has grit going everwhere. I then finish them off usually with a micro-bevel at an appropiate angle/grit. Most people on Bladeforums would cringe at doing this to their knives but the people who live here don't see knives like that at all. They would not hesitate for example to take pretty much any knife for any cutting if it was the closest thing at hand and would readily take and AFCK and cut/scrape putty/gum off of concrete.

[comment about angle/bone]

Does this apply to decent stainless steels too?

No, stainless steels are tough in the way that Calista Flockhart would be fat if she ate a hamburger. Stainless steels are often compared to D2 for toughness which is one of the more brittle tool steels.

I recently deboned 4 chicken quarters and cut up the meat on a plastic tray, and the edge was reflecting light at many places.

That's not to be expected, consider the performance of the knife I cut out of a tension bar which is just mild steel. I even intentionally did unnecessary bone work. It isn't necessarily a sharpening method problem there could be many reasons, the main one is very poor steel at the edge initially.

I have the hardest time sharpening the ATS-34 in the AFCK. I feel the grain is coarser than many others. I can end up with a functional edge, but I get reflective spots where I feel I should not sooner than I expect. I really do notice how much more abrasion resistant it is from sharpening it. I also get the impression that it is fairly ductile (opposed to crisp. I guess by crisp, I mean no burr/wire edge or movement of the steel at the edge). Any ideas?

This is a common problem with ATS-34, it is one of the steels most complained about in regards to sharpening. Benchmade also leaves their edges fairly thick (or used to anyway) which compounds the low grindability significantly. AUS-8A has a much lower volume of primary carbides than ATS-34 (it is about a third of the distance from the carbon saturation line) so it grinds much easier. As you have to do much more work to grind ATS-34 which means there can also be issues with coarse scratches being retained and inducing weakened edges. You might want to check the edge under light magnification, 10-20 times is enough to solve a lot of these types of problems.

So by way of illustration, if I was to try this with, say a flat ground kitchen knife with a 15 degree secondary bevel, I would place the blade flat on it's primary grind and hone away in flat semi circles until the secondary bevel disappears and a slightly convexed full grind (spine to edge) was left? Quite a bit more time required than the original post suggests, then.

It is usually used on really thin knives with hollow grinds. Alvin would start out by taking that knife to a wheel and thinning the edge back with a high hollow grind which would allow that low angle honing very efficiently. Without this it is very time consuming to do without power equipment, I usually just use a slat belt sander to apply a heavy relief. You can also try a file and a vice or just a really coarse hone. Once you have the relief applied subsequent sharpenings are much faster.

Is the Fikes video somewhere on this forum?

It is on CD, if he doesn't mind I'll send you mine.

The type of stroke you use doesn't really matter ...

It makes a big difference in several respects (slicing aggression, durability, friction) if you stop before a high polish which sets the finish at the grain structure of the steel.

As for the finish and scratching the side of the blade, who says you have to stop at the coarse hone?

You can satin or mirror polish the blade every time you sharpen if you want, this however is generally not advisible for efficiency reasons especially on abrasion resistant steels.

-Cliff

 

[Easyrider]

There are many different ways to sharpen. No one method is right for every knife or every knife user. I do the convex on a bench hone because it works for me and I don't really care about resale. It's the easiest way for me to thin the blade grind on factory knives I think they are ground too thick in most cases. I don't really understand the scratched finish part. After I'm done sharpening I've put a really nice finish on the knife that I can reproduce easily after I've scratched it from use.

Good post!

I'm not an expert nor do I believe that I can get the sharpest knife in the world this way but I also use benchstones to convex my user knives. I get an edge I'm happy with and works well for me.

Sure the spyderco ceramic stones scratch my blade but guess what? I don't care!

I return you to your regular scheduled programing.

 

[kel_aa]

They would not hesitate for example to take pretty much any knife for any cutting if it was the closest thing at hand and would readily take and AFCK and cut/scrape putty/gum off of concrete.

This is assuming you handed them one, because they would never buy one in the first place? For us, that's why we have our Cold Steel Voyagers, various CRKT's, Gerbers, Mora's, M-Techs, and what not. But once they spend the money to get a "nicer" knife and get to know the "story", I think they would start appreciating it too.

I understand that the choice of blade profiles and steels commerically available may be limited. For instance, I see it might make a lot of sense to put down 100 some dollars US to for a Swamp Rat and take the edge down for your need. But on the other hand, arn't you buying what the designer/maker's idea of a knife? You don't buy a $20 seasoned steak from a steakhouse only to walk to the sink, wash off the seasoning and "reflavour" it yourself. For the "lower" knives, there isn't much unique design at all, sort of like a raw slab of meat. But as you move up the ladder, there naturally will be more resistance to you modifiying the qualities that made it unqiue.

 

[Cliff Stamp]

This is assuming you handed them one, because they would never buy one in the first place?

Generally not, though they often get them as gifts. I have seen fine ceramic bladed knives for example chipped and the tips broken because they were used for digging for worms. Yes it will get damaged, so you sharpen it and move on. Eventually it gets worn out so it gets replaced. You make life easy for you, not your tools. A lot of people on bladeforums will preach "use the right tool for the right job" endlessly but quite frankly what I actually seen is closer to "use what ever gets the job done the fastest" because working guys are on a time line and don't carry a lot of equipment and tend to really highly rate robust equipment for that reason. This is speaking more of general carpentry (framing) vs finish work and similar. Now would they pay $200 for a folding knife, no, but if they did for some reason it would get treated just as harshly as a $2 one.

But once they spend the money to get a "nicer" knife and get to know the "story", I think they would start appreciating it too.

They have lots of equipment which is as expensive as the knives we buy, even more so, and they are not delicate with that either. For example awhile back I was giving my brother a hand on some framing and he was using a new air nailer he just bought. He was slamming it down extremely violently so I asked him if it was actually made to be used like that. He said no, and that he would likely wear it out very shortly. However the time he would save by using it so harsh is actually far more monetary wise than the cost of the nailer. They don't see the tools as anything in and of themselves just something used and used up to get something actually important done. On bladeforums though people are buying knives for the sake of having them, not to do something, so it is a very different viewpoint. How many Sebenza's are actually used up? How many Pronghorns?

But on the other hand, arn't you buying what the designer/maker's idea of a knife?

To some extent, but I often see features on a knife that I am interested in with others I know I will change, but I will still get the knife because I can change them. The U2 for example is a nice light utility knife and it is even better now that Krein hollow ground it. A lot of people look only at what knives are stock when it would be better in general to look at what they can be with either slight user mods or taking advnatage of customizations from makers like Krein and Wilson. This can often give you close to true custom performance for production level prices.

-Cliff

 

[newshooter04]

cliff im afraid im a person like u describe. i have a steve dunn skinner for years and i use it for everything that comes along.it looks like a 2.00 china knife after u got done with it but it holds a edge and feels right so i will continue to use it. steves daddy told me when i got it from him and he saw how i treated it that i had no business with an expensive knife.knives are tools and a tool must have good steel and a good shape and feel to do a job correctly and if not toss it on a shelf and get another.if you think i have no business with a " special knife" you may be right.
i sharpen my knives flat and thin the blade as much as possible depending on the job.
david

 

[kel_aa]

Yes, the use many here on put on knives they are fond of can often be trivial. More like using it once in a while just to reassure ourselves that it is still a knife and not an object of display.

I agree it is a different perspective. Most of us cannot totally omit style. It is a matter of taste, of personality, of "adventureness." A person is allowed a more than basic wristwatch and still not be called vain. A person can have clothing of color that is not the most stain-invisible or fabric that is not the most wear-resistant. Same with knives that we know to be less than optimal for the money but still enjoy otherwise. Yes, your Sebenza is awesome [in performance], but many of us don't want that kind of awesomeness everyday considering the price [in beauty] that we pay. But hopefully, the smarter ones will realize which one will cut easier for longer if they had to pick one to be lost in the woods with.

 

[Joe-Dirt]

I don't understand how you guys are getting a convex edge by laying a knife flat and moving it in circles. Do you tilt the knife up and down while doing it?

Laying a knife flat and moving it in circles would simply scratch the sides a bunch?

I'm lost obviously.

 

[kel_aa]

I think what they are saying is that unless you have mechanically stablized hands and arms, the small variations in the angle of the knife with respect to the stone surface resulting from your movement as well as the curviature of the stone will result in a very slightly convexed edge.

 

[Mtn Hawk]

Wow, a lot of great info here! :thumbup: Unfortunately I missed this thread the first time. Glad it came back around. thombrogan thanks for starting it and Abe thanks for resurrecting it.

thombrogan--

The sharpening method you describe in your initial post seems like the same technique that John Juranitch advocates in his book The Razor Edge Book Of Sharpening. Is it, or am I missing something?

Thank you........

 

[thombrogan]

Mtn Hawk,

Aside from Juranitch's insistence that one needs edge-guides (i.e. Sharpmaker/Lansky presets or his style stuff), yep.

kel_aa,

To point that I do agree with you that looks can matter on a working knife, you can spend a few hundred bucks on an EdgePro and soup it up with all sorts of doo-dads (like I did and do) or you can get over it and add quick/easy/affordable/effective to your bag of tricks let looks develop over time (that's the db way!).

Easyrider,

Thanks for weighing in on the side of good, ceramic benchstones and a can-do/will-do attitude.