Touching up "Super Steels" with Ceramic Rods

[AFAustin]

For practically my entire "knife life", I've had traditionals with their typical softer steels. I've had good success setting the initial edges with my Work Sharp Ken Onion, and then maintaining them with my Idahone and Sharpmaker ceramic rod set-ups, along with strops.

Recently I've acquired a few blades in harder, more-or-less "super steels": M390, S30V and S35VN, and maybe more to come. I've been able to set the initial edges with my WSKO (although it took quite a bit longer!), but am wondering about using the Idahone and Sharpmaker for touch-ups. Somewhere I read a post by David (Obsessed with Edges) saying, as I recall it, that it was bad to use the ceramics on these harder steels. Something about gumming them up, and in a different way than softer steels which can be easily cleaned off. (I do have CBN rods for the Sharpmaker, but those are too coarse for touch-ups.)

I'd appreciate any insight, and if I'm lucky David will see this and remind me of exactly what he said.

Thanks,

Andrew

 

[Culprit99]

I'm regurgitating what I've read elsewhere, but my experience does align with this: To sharpen a steel with Vanadium Carbides, you need a medium that will cut and shape those carbides, not just knock them loose out of the matrix metal leaving a bare metal edge full of holes where the carbides used to be. That basically means you need to use diamond stones, rods, or paste on a strop. The best entry into that arena, in my opinion, is this three-grit diamond rod from Buck for under $42.00 And if you give them your email and phone number, you get 10% off your first order. And if you manage to checkout without adding something else to the cart to get over $99 for free shipping, then you're a better man than I!

https://www.buckknives.com/product/edgetek-ultra-steel-10/?sku=97082-B

 

[Culprit99]

PS: S30V was many people's first foray into high Vanadium Carbide steels. Consequently I think a lot of them started sharpening with the traditional material stones they already owned. I think that's where S30V got the stereotype that it takes a mediocre edge and holds it forever, never seeming to get duller. I think many people were dislodging the carbides, getting the best edge they could - which was less than the steel was capable of - and the hardness of the carbides under the surface would hold that edge for longer than their traditional steels held a finer edge.

Also, going with too shallow of an angle on carbide steels doesn't leave enough meat behind the edge to hold the carbides in position. Of course all this is at the microscopic level and is sort of splitting hairs - but that seems to be what a lot of folks want out of their knives, so I suppose it's not too nit-picky.

 

[AFAustin]

Culprit99, thanks for your posts and information. Your explanation of how S30V got the "takes a mediocre edge and holds it forever" reputation seems logical.

Andrew

 

[Obsessed with Edges]

For practically my entire "knife life", I've had traditionals with their typical softer steels. I've had good success setting the initial edges with my Work Sharp Ken Onion, and then maintaining them with my Idahone and Sharpmaker ceramic rod set-ups, along with strops.

Recently I've acquired a few blades in harder, more-or-less "super steels": M390, S30V and S35VN, and maybe more to come. I've been able to set the initial edges with my WSKO (although it took quite a bit longer!), but am wondering about using the Idahone and Sharpmaker for touch-ups. Somewhere I read a post by David (Obsessed with Edges) saying, as I recall it, that it was bad to use the ceramics on these harder steels. Something about gumming them up, and in a different way than softer steels which can be easily cleaned off. (I do have CBN rods for the Sharpmaker, but those are too coarse for touch-ups.)

I'd appreciate any insight, and if I'm lucky David will see this and remind me of exactly what he said.

Thanks,

Andrew

Hi Andrew.

My take these days, with ceramic hones and high-wear steels, amounts to this:

It can work fairly well if used very minimally. By 'minimally', I mean that it can enhance sharpness by cleaning up the edge of the weakened remnants of burrs and maybe enhance portions of the edge not holding carbides. But I've always noticed, if I go too far with the ceramic after honing on diamonds, much of the slicing aggression produced on the diamond hones will be lost in doing so. Past a certain point, the edge becomes more burnished on steels like these, using a ceramic. And I still attribute that burnishing effect to the limitations (in hardness) of the ceramic grit, which will be less hard than the vanadium carbides in these steels. I've periodically revisited my assumptions about this on blades in steels like S30V or even D2. And after more experimentation with it, I keep circling back and refinishing the edge on diamond, to get back the cutting aggression that always seems to diminish past a certain point on ceramics.

Other issues, like the 'gumming up' of the hones you mentioned, can still be aggravated even more on high-wear steels. It's basically true with any steel really, on ceramics, if the hones aren't kept clean while working - the swarf will clog them after much grinding or heavy polishing, and they'll lose aggression. But additionally, with steels containing very much hard carbide content, there'll also be more abrasive wear on the ceramic hones themselves, because the carbides in the steel will essentially polish the grit on the hone over time if they're frequently used with such steels to any great extent.

I still firmly believe that the relative hardness between a given grit and the materials being cut/ground upon it will be THE #1 RULE in determining how effective and how efficient a sharpening experience will be with a given steel and a ceramic (or any other hone). Sharpening becomes a lot easier if you choose an abrasive that is hard enough to easily cut literally any component in the steel, and not just the matrix steel itself. For me, that means any steel with more than 3-4% vanadium (like S30V) will always be sharpened on nothing but diamond in my uses (CBN would apply here too - but I haven't used it and don't own anything in CBN).

 

[AFAustin]

David, I was hoping you might weigh in here---thanks. Your explanations are very helpful, as always.

Sounds like, to complement my ceramic V systems, I need a V system with fine diamond rods. And as luck would have it, I recently gifted my Work Sharp Angle Set which includes just that. Oh well, it would be pretty inexpensive to replace.

Andrew

 

[Obsessed with Edges]

David, I was hoping you might weigh in here---thanks. Your explanations are very helpful, as always.

Sounds like, to complement my ceramic V systems, I need a V system with fine diamond rods. And as luck would have it, I recently gifted my Work Sharp Angle Set which includes just that. Oh well, it would be pretty inexpensive to replace.

Andrew

Another avenue that can work, if you're pursuing a polish on high-wear steels, is setting aside the ceramics for hard strops with diamond or cbn compound. I personally don't polish edges much anymore, as I now prefer more toothy bite in all my edges. But when I was doing that, I found that using something like 3-micron diamond compound (DMT's Dia-Paste) on hard wood like basswood, maple, oak, etc. can take the refinement further while still protecting the crispness of the apex, without that burnishing effect of ceramics. So basically, my same rule applies with regard to doing all finishing on diamond (or cbn) for steels like these.

 

[AFAustin]

David, thanks again. I do have a couple of strops loaded with diamond paste, although it's 1-micron.

I also just recalled I've got a Work Sharp Guided (manual) Sharpening System put away. It has diamond plates up to 800 grit. When I first got it I wasn't really getting the hang of it. Maybe I should give it another try.....

Andrew

 

[Khromo]

I recently spent some time re-profiling and sharpening a couple of new M390 blades. I used Ultra Sharp diamond stones from 300/600/1.2K/3K. You could watch the scratch pattern getting finer with each grit, although it took a while, especially re-profiling from about 25 degrees per side down to 20. The blades were popping hair and cutting thin paper early in the progression. Everything looked excellent under 10-50X magnification, very shiny.

Using my new Sharp tester, I got into respectable 150-200 gram territory easily enough. I then tried some 3 micron aluminum oxide lapping film on glass. The test scores did not improve at all, and may have gotten more erratic, although that might have been operator error, as I am new to the tester.

I was looking for scores in the 100-150 range, so I tried some 3 micron diamond lapping compound on leather. Those blades came to life! The BESS scores dropped down to a fairly consistent average of 125 across the cutting edges.

The substrate changed from film on glass to leather, but I was using light pressure so it probably didn't matter too much. The abrasive changed from AO to diamonds, and I think this is where the performance boost came from This would agree with David's explanation of using the harder cutting agent to get the best results. At least with these high vanadium steels.

 

[AFAustin]

Another avenue that can work, if you're pursuing a polish on high-wear steels, is setting aside the ceramics for hard strops with diamond or cbn compound. I personally don't polish edges much, anymore, as I now prefer more toothy bite in all my edges. But when I was doing that, I found that using something like 3-micron diamond compound (DMT's Dia-Paste) on hard wood like basswood, maple, oak, etc. can take the refinement further while still protecting the crispness of the apex, without that burnishing effect of ceramics. So basically, my same rule applies with regard to doing all finishing on diamond (or cbn) for steels like these.

This conversation was a couple of weeks ago, but David, if you happen to see this, let me ask something. This may be splitting hairs (couldn't resist) but, given that I already have a strop with 1 micron DMT Dia-Paste, if I wanted to add one more, would you go with 3 micron or 6 micron?

Thanks,

Andrew

 

[KentOBean2]

This conversation was a couple of weeks ago, but David, if you happen to see this, let me ask something. This may be splitting hairs (couldn't resist) but, given that I already have a strop with 1 micron DMT Dia-Paste, if I wanted to add one more, would you go with 3 micron or 6 micron?

Hello there I’m new here and I’m interested in what Davids response will be.
But maybe this will be help until then.

In My experience I would go with 3 micron
I have both but I don’t use my lower grit strops that much anymore (I now prefer edges fresh off the stone or a finer stone straight to 1 micron then .5 micron .25 micron etc)
yet on occasion if I do use a full stopping progression I skip the 6 micron as you can easily jump to the 3 after most medium grit stones

one exception to this is if you want to experiment with burr removal on the strops
that was my reason for purchasing the 6 micron in the first place. But I never did much with it as it seems best to just remove it on the stones anyway

Thanks,

Kent

 

[AFAustin]

Kent, thanks for your post. My situation is a bit different in that I set the original edge with a Work Sharp Ken Onion belt progression. It does a good job on that even with "super steels", although of course it takes longer. I'm a poor freehander, and don't have a proper diamond stone set-up in any event---and prefer not having to return to the belts just for a touch-up---so I'm really looking for a way to maintain edges on the harder steels with just a diamond loaded strop.

Andrew

 

[Obsessed with Edges]

This conversation was a couple of weeks ago, but David, if you happen to see this, let me ask something. This may be splitting hairs (couldn't resist) but, given that I already have a strop with 1 micron DMT Dia-Paste, if I wanted to add one more, would you go with 3 micron or 6 micron?

Thanks,

Andrew

I originally bought DMT's kit of three of their pastes, in 6, 3 and 1 micron. I've heavily favored the 3-micron over the others - it's really kind of amazing how fast it works to a high polish (used on wood), after following something like an EF (9 micron) or EEF (3 micron) DMT hone. I have occasionally used the 1-micron for very light touch-up stropping as well. I've almost never used the 6-micron, except just to satisfy my own curiosity about how it works. I tend to believe anything I can accomplish on a ceramic hone will do as well as any results I've gotten from the 6-micron strops (also on wood). In fact, between the two, I tend to favor the little extra bit of toothy bite left by a ceramic. The 6-micron diamond paste does refine the apex - but I've also noticed it tends to diminish some of that toothy bite I prefer. That's the main reason I don't use it much. This is generally true with any stropping using fine compounds. But at least the finer compounds, like 3-micron and finer, seem to do much better if you're pursuing a very high polish.

I don't polish my bevels much anymore, instead favoring a mid/high-grit toothy bite from a stone, which means I'm not generally stropping with these compounds much anymore. But that doesn't mean I haven't been impressed with some of them, if polishing is the goal.

 

[AFAustin]

Thanks, David. I appreciate your detailed reply. It's been many years now and I've never stopped learning from you.

Andrew

 

[Obsessed with Edges]

Thanks, David. I appreciate your detailed reply. It's been many years now and I've never stopped learning from you.

Andrew

Very kind words. Thank you, Andrew.

 

[lonestar1979]

I touched up s30v on sharpmaker brown rods,few light strokes,but mostly use diamond dmt....,and got great results