Why am I not getting consistently sharp knives?

Legacy Forum Archive basic-techniques-and-sharpening-strategies
1

I continue to be perplexed and frustrated by the results I’m getting with my WEPS. I have the 100-1000 diamond stones plus the Super Fine ceramics (1200/1600) and I typically have been using all of them. The process of sharpening always seems to be going well, but it doesn’t consistently result in a seriously sharp knife and I can’t figure out why. Here’s a typical progression, see if you can spot anything I’m doing wrong.

  1. Clamp knife, use marker to cover bevel, set angles to eliminate marker, set fore/aft position to make bevel width consistent
  2. Grind knife to desired sharpening angle with 100 stones.
  3. Confirm burr can be raised quickly and easily on both sides of the edge with the 100 stones
  4. Do 25 strokes per side, alternating, of the elliptic trainer motion the WEPS is famous for.
  5. Switch to 200 stones. Use up/down scrubbing motions to remove all traces of 100 grit scratches.
  6. Confirm burr can be raised quickly and easily on both sides of the edge with the 100 stones
  7. Do 25 strokes per side, alternating, of the elliptic trainer motion the WEPS is famous for.
    …
    Repeat steps 5 through 7 to work my way up through the stones one by one all the way up to the 1000 grit diamond. That’s the last stone I can feel the burr on.
    …
    8] Clean knife with damp paper towel.
  8. Switch to 1200 ceramic. Use up/down scrubbing motions until the stone stops feeling like it’s doing anything.
  9. Do 25 strokes per side, alternating, of the elliptic trainer motion the WEPS is famous for.
  10. Repeat 8-10 with the 1600 ceramic.

So, I raised a burr consistently at least up to 1000 grit, I took quite a lot of strokes at each grit. And more to the point, this is how I do every knife I sharpen yet I’m getting inconsistent results. For instance, I have several Delicas that ride around in various pockets. The Delicas (VG-10 steel) have all been improved by this sharpening but they’re the knives not getting seriously sharp. They’ll push-cut phone book paper about 2” from where I’m holding it yet they won’t shave arm hair off (though it does pull at it pretty hard). On the other hand, a Kershaw Leek (steel unknown) I sharpened last night moves through the paper much easier AND slices arm hair right off.

Why am I sometimes ending up with just a sharp enough knife and sometimes ending up with a seriously sharp knife?

2

To be brief, I suggest you only go below 400 grit if you are doing some serious re-profiling. The coarse grits will take chips out of a refined edge which are then difficult to remove and difficult to see. The edge quality is largely dependent on the steel type, which explains your experience with different blades.

25 strokes is excessive, depending on the blade length. A blade such as your Delicas (My EDC is a Delica in ZDP-189) probably needs only 6-8 strokes. The extra strokes don’t do much, except with the lower grits where they can do a lot of damage. They do serve to remove every scratch, but at the expense of extra work and unnecessary steel removal. And they serve to aggravate you when the result isn’t reflective of the effort expended.

For all you’re investing in this, I suggest you get a handheld microscope. Seeing what’s actually happening at the edge will remove a lot of the doubt. If you have an extra laptop laying around, a good USB microscope can be had for $100 or less. Of all the stuff I’ve collected for my WE setup, the microscope was the best investment I made.

And to restate my first point, I never touch my Delica with anything less than 600 Grit.

3

I think from your description that you are overworking the method. Most importantly, the burr is only raised once. This is done with the scrubbing motion and when there is a burr along the whole edge, then you switch to the 200 stone and proceed with gentle strokes and no more scrubbing is necessary or even a good idea. Too much pressure on the edge with the diamond paddles is counterproductive and also wasteful of good steel. Proceed through the steps using the various paddles with a light hand. You will be rewarded with the razor sharp edges you desire.

Cheers
Leo

4

I believe your weakness is in steps 1,2 and 3. Others jump in here and see if I have nailed it or not.
Leo

5

This is an interesting one, because on paper you seem to be doing everything right.

Well, perhaps right is not the right word, but you’re not doing anything wrong. As Tom pointed out, maybe you’re overdoing things, but this should not have any detrimental effects - provided your knives are made of decent steel. When I was learning sharpening with the WEPS I overdid things in an even much larger way, simply to exclude the possibility that I did not do enough. This may cause some unneeded steel removal, but that’s as bad as the side-effects go.

However, I was struck by two observations:

[ul]
[li]You write you’re able to feel a burr after the 1000 grit stones. Are you sure? I’m not saying you can’t, but I certainly can’t feel a burr after these stones. If you are in error, you may also have mistakenly interpreted something else for a burr after the 100 grit stones. And, as Leo wrote, this initial burr is crucial.[/li]
[li]Both knives that don’t get sharp enough are Delicas with VG10 steel. Now VG10 is a steel that requires a good heat treatment, which is difficult. If it is done well, you’ve got a great steel. If it’s done wrong, you end up with a very chippy steel. A company renowned for getting their VG10 heat treatment wrong is KAI on their KAI Shun knives (coincidentally the same company that makes your Leek :cheer: ). I don’t know whether Spyderco got their heat treatment on this VG10 right or wrong. They’re usually pretty good at this, but I also recently read a report by a forum member about how they got their heat treatment on S110V horribly wrong. The result: a very chippy edge.

If your VG10 is chippy, Tom’s remarks make a lot of sense. Normally I have no problem starting sharpening with the 100 grit stones, I never experience chipping on a decent steel. However, if the steel is bad, this may be an issue. In that case also using light pressure is even more important than it normally is.[/li]
[/ul]

So my advice would be:
[ul]
[li]make absolutely positively 100% sure you detect a burr after the 100 grit stones;[/li]
[li]try some more knives with a decent steel (like the Leek - it’s probably made of S30V or 14C26 if it’s not printed on the blade) to see whether it is the Spyderco VG10 that causes the problem.[/li]
[/ul]

And if this doesn’t solve the problem, I second Toms advice on getting a microscope. You could start with a thingy that’s called a loupe (it looks like a jeweller’s loupe) but is actually a microscope and that enlarges about 70 times. I got mine from a Chinese site for less than $5. I’ve forgotten where I got it from or what it’s called, but if you want to know, I can look it up.

Success! And please keep us informed of how you go.

6

Yes, I’m absolutely sure that I can feel the burr on everything from 800 down. I have a lot of experience sharpening woodworking tools via other methods and I know what I’m feeling for with a burr. At 1000 grit, I guess you’d say I feel the burr by implication. I mean that, if I work one side for a while and then drag my fingers over the edge (nearly parallel to the side of the knife, not parallel to the table), it feels different on the side where the burr should be than it does on the side I was working. To me, this implies I’m feeling the burr. Though only BARELY! It’s not like it is at coarser grits were you can definitely feel there’s this metal hook folded over to one side.

It’s sort of like the difference in rubbing velvet with the grain vs against it if you’ve ever done that.

Also, I think a microscope will be my next major sharpening purchase, though it won’t be soon. I think I’d stand a lot better chance of figuring this out if I could see what’s going on.

7

I’m jumping in very late here because I’ve been out of town… Leo mentioned light pressure and I’d like to emphasize that. As you move to higher and higher grits, your pressure should get lighter and lighter until it is whisper-light with the finest stones.

8

I had a similar problem and it is simply an issue with the burr.

When you form a burr with the very low grits it is nothing more than damaged steel. This damage can extend deeper than the burr you see and feel, even if you look under magnification. This is especially true if the steel was heavily used and the edge was in a highly deformed state initially, highly fatigued.

There are a number of solutions :

a) Keep progressing to ultra fine stones, strops

b) cut the burr off during the sharpening with a wood block, hard felt pad, etc.

Now (a) might not be practical as you might want a more coarse finish and (b) isn’t ideal as it smashes the edge apart. The ideal solution is

c) Use a couple of very light passes at a much higher angle to remove the burr and then back sharpen to remove the higher micro-bevel

however if you :

-cut the edge off flat before you sharpen
-don’t form a very heavy burr
-use very light strokes with water as you approach the apex

then you can minimize the need for it.

9

Is the “cutting the edge off” you’re mentioning the idea of de-stressing the edge by running a stone over it at right angles to the blade that I’ve seen you talk about before?

10

Yeah, this freaks some people out because they see it as wasteful of the steel. It maybe even seems that way at first as why cut off metal from the edge? I would make a few points :

-you are cutting off just barely enough to see usually, this is depth of maybe 5-10 microns
-that steel is heavily damaged anyway and won’t form an edge well

and here is where it gets really useful :

-it prevents isolated wear from setting in
-it gives you a strong visual references

In fact as I don’t burr sharpen I don’t lose any metal in sharpening at all from the width of the blade, what is lost is from use only. I have sharpened the Spyderco Lum ten times in the last week (just doing hemp runs) and you would not be able to tell from any use pictures as it isn’t even 0.1 of a mm lost.

As with everything related to method there are personal influences so the most I would say is try it, see if it works for you, if it doesn’t I would like to hear about it and why - mainly for curiosity. But I won’t kill you or anything if you don’t do it just because I do it. I am Canadian, the most I would do is only offer you plain coffee instead of a double double.

11

I would add this, lot of good advice already. Can’t stress enough to use light pressure. Before I go to the next stone I do 5-10 more strokes as light as possible.

If your stones are not broken in that may be the number one problem. My first 5 knives were not great. The next 5 better but not excellent. After that it got much better. It takes about 10 to break in the stones and also to get your technique going. This is the minimum it definitely keeps getting better after 10 knives. I sharpened a beater knife 3 times to get practice and break the stones in.

Slow down and focus on every stoke, making good contact with the stone, light pressure, not rolling the stone, keeping it flat against the edge. In the beginning I got ok edges but missed spots, like the tip. I was not making even contact when I started my stroke.

12

Glad to read this…I will keep working on our kitchen knives until sharpening improves. I will also go much lighter.

13

I’ve had excellent result with this technique:

Make a burr with the stone you start with wether it be 100 or 400. Use scrubbing motions with very light pressure with all of the diamond stone no sweeping motions. On the 1000 diamonds use the scrubbing motion starting on one side starting with 5 passes. One pass is starting at the heel going to the tip and back to the heel, that’s one. Once you do five switch to the other side and do 5. Then back to the other side 4 passes. 3,2,1 until the last scrubbing is only from the heel to the tip. Then move onto the micro or superfine stones (I have the microfine) and only do the classic bicycle motion. At the end of this process I will have an edge so fine it’s scary to touch and is so sharp I don’t even have to test its cutting ability on paper because it will literally fly through paper with zero resistance.