Getting the most out of your Norton Crystolon fine stone

[maximus83]

Well from further experimenting with my Kershaw M390, made a few tentative conclusions. These fit what was expected, but good to validate.

1. You can get a good utility edge on M390 directly off a Crystolon fine, plus strop with cbn. For somebody not looking to whittle hairs and do other parlor sharpness tricks, this is a perfectly usable real world edge.
2. You can get a noticeably better edge by using the SharpPebble stone, first the 400 (320 ANSI) side, then the 1K (500 ANSI) side, finishing with light edge-trailing strokes on a clean stone, plus strop with cbn. The SP does make a noticeable improvement that, IMHO, is worth the $26.
3. But I got head and shoulders the best edge yet by sharpening first on DMT coarse (325), then adding DMT EF (1200), then strop with cbn. This edge does all the paper and receipt and paper towel slicing tests effortlessly, and hair pops off your arm onto the blade. You could not get close to these results with the other approaches.

The real game-changer with M390 IMHO: you've gotta use high-grit diamonds, in this case, DMT EF or higher. There's not a better way I've found yet to get an M390 blade extremely sharp.

Next thing to test: go back to steps 1 and 2 above, tack on the DMT EF after using the Crystolon F, and after using the SP 500 side. What I hope to find is I can use coarse SiC stones plus high-grit diamonds, and can get results as good as (3) above, where I used all diamonds.

 

[maximus83]

I think the India could give a finer finish. It's the way it breaks in. The SiC seems like it will always shed more grit as it sharpens and those particles will grind finer. But the SiC will cut tougher steels. DM

I can't speak to the India, but this afternoon I tested AF versus the SP. I had 2 copies of the same Schrade cheap folder, put them both thru the same process:

1. Profile on coarse Crystolon to reset to fresh bevels.
2. Take 1 folder, and apex on Arctic Fox. Take the other, apex on SP 500 ANSI side.

Results:

• Both had good utility edges that slice newsprint.
• Both would shave arm hair, but AF shaves more, and with noticeably less friction.
• The AF has a slightly finer visible finish, as expected. In each photo below, the knife on the left was done by the AF, the one on the right was done by the SP. Not sure if the photos illustrate that, the light was above from the left so it was hard to get it to hit both blades equally. I inspected under a 30x magnifier and the AF scratch pattern was just slightly finer.
• My takeaway here: AF provides a slightly nicer finish and edge than the SP 500 (ANSI) side, on NON super steels. This would support my hunch that I want to keep using AF as my primary sharpening stone on my NON super steel knives. If this theory holds up with further testing, then I suspect it would also apply to folks who use the India. That said, the SP is a very impressive stone so far, and for coarse work on super steels, I plan to keep using it.

 

[David Martin]

I suspect both blades were 420 steel or the China version. So, this is good, predictable results for working them in this manner. I must
agree w/ you about the lighting and pictures. Even with simple pictures, lighting can be a problem. So, don't worry much about it. Just
give us your findings and were happy. Doesn't look like you made any off angle pushes on the coarse stone. Your learning. Thank you. DM

 

[cbwx34]

I can't speak to the India, but this afternoon I tested AF versus the SP. I had 2 copies of the same Schrade cheap folder, put them both thru the same process:

1. Profile on coarse Crystolon to reset to fresh bevels.
2. Take 1 folder, and apex on Arctic Fox. Take the other, apex on SP 500 ANSI side.

Results:

• Both had good utility edges that slice newsprint.
• Both would shave arm hair, but AF shaves more, and with noticeably less friction.
• The AF has a slightly finer visible finish, as expected. In each photo below, the knife on the left was done by the AF, the one on the right was done by the SP. Not sure if the photos illustrate that, the light was above from the left so it was hard to get it to hit both blades equally. I inspected under a 30x magnifier and the AF scratch pattern was just slightly finer.
• My takeaway here: AF provides a slightly nicer finish and edge than the SP 500 (ANSI) side, on NON super steels. This would support my hunch that I want to keep using AF as my primary sharpening stone on my NON super steel knives. If this theory holds up with further testing, then I suspect it would also apply to folks who use the India. That said, the SP is a very impressive stone so far, and for coarse work on super steels, I plan to keep using it.

I would add... the blade on the left looks to have a wider bevel... so maybe a little better blade geometry?... should equal a better cut.

 

[Obsessed with Edges]

I would add... the blade on the left looks to have a wider bevel... so maybe a little better blade geometry?... should equal a better cut.

I'm seeing that too. Maybe a swap of knife-to-stone and retest will show if the improved cutting (shaving, etc) follows the same knife, or a particular stone. I'd expect to still see differences in visible finish, between dissimilar stones. But even then, an edge with better geometry should still perform better, even if the finish may be different as compared to another blade at wider geometry.

Thinner geometry almost always wins out, rather than particular sharpening media/methods. I'm finding it fixes almost all cutting performance issues, ultimately. And a thinner edge grind makes the whole process inherently simpler; i.e., a thinner edge will respond more easily and noticeably to a wider variety of touch-up methods, often using even simpler & less sophisticated tools, because the foundation of the edge is already set up for it (thinner, in other words).


David

 

[maximus83]

^Yep agree, totally worth checking out and running this test again. FWIW, BladeHQ where I got these reports the steel type is 9Cr18MoV stainless. I will reprofile both to get the edge bevels more consistent with each other for the 2nd test. The challenge is time: running these test with photos is fun, but I usually only get enough time to do stuff this involved on weekends.

One thing that made it tricky to get the bevels consistent on these particular blades is that they are extremely sloppily ground from the factory. There are visible differences between the blades. Example: look at the one on the right, it actually has a small recurve ground into the blade from the factory, I do not think that was intentional and the one on the left does not have it. Will need to do some serious grinding on the one on the right to remove the recurve and thin behind the edge, then hopefully I can get the bevels to come out more similar.

 

[Obsessed with Edges]

^Yep agree, totally worth checking out and running this test again. FWIW, BladeHQ where I got these reports the steel type is 9Cr18MoV stainless. I will reprofile both to get the edge bevels more consistent with each other for the 2nd test. The challenge is time: running these test with photos is fun, but I usually only get enough time to do stuff this involved on weekends.

One thing that made it tricky to get the bevels consistent on these particular blades is that they are extremely sloppily ground from the factory. There are visible differences between the blades. Example: look at the one on the right, it actually has a small recurve ground into the blade from the factory, I do not think that was intentional and the one on the left does not have it. Will need to do some serious grinding on the one on the right to remove the recurve and thin behind the edge, then hopefully I can get the bevels to come out more similar.

If you have the means to do it (dial caliper, micrometer), it'd be worth measuring thickness of the grinds on each as well, to account for another variable (possibly). With relatively inexpensive factory knives, that can vary all over the place as well. Sometimes wider bevels may just be an indicator of a thicker primary grind behind the edge, with the edge itself ground to the same angle as on a thinner-ground blade, which itself would show narrower bevels at the same angle.

9Cr18MoV stainless would be roughly similar in makeup to 440C (~1% carbon +/-, 16-18% chromium).


David

 

[BluntCut MetalWorks]

I expect edge finished with ~400 grit AlO (ArticFox Stone) be slightly more refine than ~400grit SiC (SharpPebble). From pic - bevel width of AlO/left is about 20-25% wider than SiC/right, hence had major affect in sharpening psi.

If left bevel has 10 psi, then right bevel psi = left_psi / (0.8^2) ~= 15.6 psi. Abrasive comparison isn't valid at 56% psi delta. Nevertheless, individual result is useful - e.g. slice thin paper, shave-ability, etc..

 

[maximus83]

OK OK, I'll run the test again. Geez, you guys are a tough crowd on an amateur weekend sharpener.

 

[BluntCut MetalWorks]

It takes major gut to 'share by show' in public, a big for you. Humble has, grace and doubt, edges. You are just as nut as many of us around here

OK OK, I'll run the test again. Geez, you guys are a tough crowd on an amateur weekend sharpener.

 

[HeavyHanded]

OK OK, I'll run the test again. Geez, you guys are a tough crowd on an amateur weekend sharpener.

Comparing medium finish stones on a couple of budget pocket knives to an informal edge quality eval.

Calipers? Lighting? PSI delta?

You are definitely getting your chops busted here .

I'd just come back and say I had more convex to the edge bevel in the knife on the left and leave it at that.

Maybe even include a close-up....

 

[cbwx34]

OK OK, I'll run the test again. Geez, you guys are a tough crowd on an amateur weekend sharpener.

Well... this is the Maintenance, Tinkering, and Arm-Chair Quarterback forum... after all....

 

[Obsessed with Edges]

OK OK, I'll run the test again. Geez, you guys are a tough crowd on an amateur weekend sharpener.

In my own comments, I was just pointing out the things also worth looking at, if one really wants to draw a meaningful comparison between cutting results as solely impacted by the stones alone. The geometry aspect, which includes both the primary grind thickness behind the edge and the edge angle itself, could render most of the other variables moot (stones, steel type & hardness, etc), if there's a significant difference in edge or primary grind geometry between the two knives.

Didn't mean to knock the time and effort given, which is still good and appreciated. All of these things are done (I hope) in the pursuit of satisfying intellectual curiosity, and simply enjoying the process and discussion as well. I wouldn't blame anyone for leaving it at that, all other technical aspects aside.

 

[maximus83]

^Oh no worries, I'm totally kidding. If I were sensitive about having my chops busted a little, I wouldn't be posting pics of my sharpening setup and my various results as I'm learning and improving technique.

Honestly, taking more time to practice than in the past, getting a few beater knives and different stone types to experiment, and getting some feedback here in the maintenance forum, are the things that have really helped most to get better sharpening results recently than I have ever gotten. So it's all good!

 

[David Martin]

OK OK, I'll run the test again. Geez, you guys are a tough crowd on an amateur weekend sharpener.

Yep, they are. I know what you mean--- having time only on the weekend. Now, w/ the time change it's dark when I get home. Just do it when
you can. But I would measure the thickness first. Which is easy. DM

 

[Chris "Anagarika"]

M maximus83 ,

Thanks for sharing. This thread has gone off leaving Norton behind, nevertheless it’s enjoyable.
With my sharpening gurus around, you’d get lots of insights here

That 9Cr if done right will serve very well.

 

[David Martin]

9Cr18MoV stainless would be roughly similar in makeup to 440C (~1% carbon +/-, 16-18% chromium).


David

Some in the know say it's closer to 440B. DM
http://zknives.com/knives/steels/9cr18mov.shtml

 

[Obsessed with Edges]

Some in the know say it's closer to 440B. DM
http://zknives.com/knives/steels/9cr18mov.shtml

Yeah, looks like it's sort of in between the two on carbon content (low end of 440C's rated carbon range, higher end of 440B's).

Thanks for that.

 

[David Martin]

Forget it. I'm not so sure there is a Expert on this. While not splitting hairs,-- there is a slight difference. Still, I wonder if it's enough we would notice. Your welcome. DM

 

[David Martin]

One thing that made it tricky to get the bevels consistent on these particular blades is that they are extremely sloppily ground from the factory. There are visible differences between the blades. Example: look at the one on the right, it actually has a small recurve ground into the blade from the factory, I do not think that was intentional and the one on the left does not have it. Will need to do some serious grinding on the one on the right to remove the recurve and thin behind the edge, then hopefully I can get the bevels to come out more similar.

I would not do a regrind. The difference is slight and through use (should you carry and use it) this can be worked out. DM