Sharpening high hardness and wear resistant steels

[bodog]

Alright, numbers for silicon carbide wet/dry and a few impressions.

Started out on a Washboard with 320 grit and it was able to cut a new bevel fairly rapidly. On to the 800 grit and things slowed way down. Some of the chipping was still in evidence that the 320 hadn't completely removed. The 800 eventually did get rid of it, a nice clean bevel after about 15 minutes of work. This would be a good stopping point for the knife, but kept going as 800 doesn't correlate to the 4k or fine ceramic.

1200 grit finish, took a few minutes to shine up the edge some more. My impression is that this has given me the best outcome of the bunch so far. No chipping, edge appeared clean, was able to shave armhair and crosscut newspaper quietly, didn't take forever, still had some catchiness to the edge though IMHO this is too high a polish for this abrasive on this steel.


Inquisitor numbers:
12 lbs push (the lowest sample was 7)

10lb draw, very nearly made 9lbs but could not do better than 2/3

Next up, diamond plates.

DMT or Eze-lap?

 

[HeavyHanded]

DMT or Eze-lap?

DMT. I have some Smith's around here too, but I only have DMT in EF and EEF

 

[HeavyHanded]

I hate to do this but am revising the numbers for the pressure cut. I have never been thrilled with the method, which was to run a fish scale from the load arm on the EI and take an average of three pulls. Two problems with this, the sampling time for the detected load does not always fall on the exact instant the line is severed, so I have to toss a lot of readings. Also, I cannot tell with 100% certainty if the reading I'm getting isn't partially influenced by resistance from the overstrike cable.

I ran a few tests using a scale under the entire widget and the numbers were a little higher than I'd been getting on the fish scale, also they are still probably influenced by resistance from the overstrike cable on the odd cut.

I made an extension to the existing load arm so I can run a weight further out. I now have static loading capability in one lb increments from 40 to 6 lbs. Since this is a static load, the only variable is how rapidly I remove support, which is a lot easier to manage. I've gotten repeated values falling into a 1 lb deviation.

Anyway, the new pressure cut number for the wet/dry is 16lbs compared to the 12 previous.

Factored to the numbers for the King 4k, that would be 24 lbs instead of the 18 previous.

 

[Wowbagger]

I don't feel I am drailling the thread; I hope you don't.
This latest several posts are helping me UNDERSTAND SLURRY It has always been a mystery to me why it is a good thing and I have avoided it for less wear resistant blades.

Light pressure on Coarse diamond plates didn't work for me. I am thinking I should have spent more time with medium to heavier force; all my xxcoarse diamond work on the S110V was with light and very light pressure which seemed to do next to nothing.

So I am in this thread to sort that out as well.

If having trouble I'd look to geometry first. A super steel that doesn't have super thin geometry is a waste of the steel's properties.

I realize that now. I swapped the knife for a better handle shape (for my taste) and longer blade : Endura 4 in ZDP-189. I didn't want to mess with the blade geometry if I sent it back to the maker. They said it was correct in grind and hardness and should have performed well. We didn't discuss the 0.030 inch behind the edge. The more I think about it the more I want to get that knife back and overhaul the liv'in 'ell out of it.

I will wait for the Spring and 2017 purchases to revisit S110V.

As far as the higher wear of the steel; the trimming I do is often on vehicles with much use and there is grit and even aluminum embedded in the rubber so I CAN use that property and was shocked at how fast the steel whined, quit and went home. I have great success, even with basic steel, grinding thin and shallow so now I want a rematch with it and have none.

PS: as far as

trying to shave thin slices and had the block in a vice or on a surface where I didn't have to worry about damage if it overshot

try putting the block on the corner of the table and cut straight down. Heck . . . the trimming I do is such small slivers I put my non knife hand on the work and pivot the blade off my thumb on that hand for more control (so I don't over shoot ).

You can imagine but photo to follow. Using the King of this work so far Ritter Grip in M390. No mods I just use it, and use it and use it.
I either push with my thumb or pivot the the blade tip forward by swinging the handle back toward me; then advance both hands forward.

I keep harping on this endlessly because I want to finally UNDERSTAND what went wrong; what I can do to overcome it. Glad I made the swap, wish I had the S110V back for another go; out of money for hundred dollar plus knives until Spring.

Thanks for addressing this.

 

[HeavyHanded]

And the numbers from the 10v on diamonds:
14 lb pressure cut
9 lb draw weight

compared to wet/dry:
16 pressure
10lb draw

Muddy Kings:
24 pressure
9lb draw


Sharpening on diamonds took about 15 minutes total compared to close to an hour with wet/dry and over an hour on ceramics and waterstones.

On the DMT coarse there was still evidence of chipping. Transition to the fine and the chipping faded away. Off the EF the edge was nice and uniform, no evidence of any edge defects from the abrasive. Off the EEF, the edge turned out very nice, slight scratch haze still in evidence. IMHO the ideal edge on this knife is probably the fine DMT, the draw cut numbers would have gone down and the pressure cut might have only gone up a lb or so at a guess.

Included some pics - first one the edge off of wet/dry over Washboard, flat and clean. It is possible to reduce inherent rounding off of wet/dry to an imperceptible level if properly handled.

Next two are off of the diamonds, turned out great. As an added observation, the primary grinds on this are top notch in terms of geometry, and even though a testing blank, no warps or any other issues. Side to side uniformity mirror image.

My tentative conclusion:
- use a coarse edge finish on a thin primary and it won't much matter what manufactured abrasive you use.
If going to a finer finish:
- use diamonds if available.
- use wet/dry over a hard surface if diamonds are unavailable.
- use waterstones with a load of mud if wet/dry and diamonds are unavailable.

Speculation:
- the muddy Kings produced a rougher finish, resulting in higher pressure cut numbers and comparable draw cut.
- the wet/dry was close in terms of finish but lack of ability to to cleanly cut the carbides resulted in higher numbers for both tests

Note:
I am going to make the Inquisitor able to do smaller increments. I was surprised how much of a difference a single pound made, especially on the pressure cut test. Am pretty sure it could return good numbers down to 1/2 lb if taken as a best two of three like I do with the draw cut numbers. To the nearest pound it is pretty much 100% consistent.

 

[awestib]

Wow - great information, thanks for doing/sharing this Martin! Happy Holidays by the way everybody.

 

[MAD777]

I have been following this thread with great interest, admittedly understanding about 50% of it. But I want to thank you for the exceptional work you've put into this. I have been collecting a few super steels and can apply the knowledge you have shared.

Sent from my SM-G900V using Tapatalk

 

[eKretz]

HH - did you do any durability testing? That might prove interesting as well. Thanks for taking the time also. This stuff does take some doing.

 

[HeavyHanded]

Ran some quick numbers using the fine side of a Norton Crystalon. It cuts this steel very rapidly and ends with a very clean edge. Due to high RC it ends with a finish a good bit finer than the rated 280 grit.

Pressure cut = 15.5 lbs
Draw cut = 8 lbs

Compared to -

diamonds:
14 lb pressure cut
9 lb draw weight

compared to wet/dry:
16 pressure
10lb draw

Muddy Kings:
24 pressure
9lb draw

Keeping in mind these are all on 3/8" Manila, pressure cut is zero draw, draw cut is 2" pull.

So now the speculative conclusion - if no diamonds just sharpen on a trusty combination Norton stone...based on cutting 3/8" Manila.

It looks like there is a rough correlation (no surprise) between higher pressure cut values and lower draw values. I've seen this before and never really dialed it in by finish. I'd imagine one might actually find a percentage value of draw to press that would correspond to performance if compared to total poundage.


Historically the lower draw value corresponds to longer life if the wear test is done with a draw. Honestly I've never done a straight pressure cut test to failure or to a target poundage. I'd imagine the lower start value on either test will relate to a longer life in a given mode. A real test might be alternating pressure/draw cut, but not sure how to do that quickly with different weight values. The Inquisitor would need an overhaul...

 

[HeavyHanded]

HH - did you do any durability testing? That might prove interesting as well. Thanks for taking the time also. This stuff does take some doing.

I haven't.

I was sort of hoping I'd get close enough numbers on some of the abrasives to make wear resistance the deciding factor, but with such different start values I'm not sure how the info would be of comparative value.

 

[Steel_Drake]

I haven't.

I was sort of hoping I'd get close enough numbers on some of the abrasives to make wear resistance the deciding factor, but with such different start values I'm not sure how the info would be of comparative value.

Very interesting results you've gotten so far. One thing that I think might be very interesting would be to repeat the three sharpening approaches used on a high hardness steel with little-to-no vanadium content. It would help to clarify how much of the observed differences in numbers are attributable to the vanadium carbide content specifically vs. reflecting inherent differences between the results the sharpening media produce.

Also, just to check, the numbers you obtained are single results obtained after one trial on each abrasive type, yes? I'm not sure if it would be worthwhile to re-run the three abrasive types just to reduce the amount of noise in the results.

It's too bad you don't have an SPS-II 1k and 3k as I think they would produce some really interesting results in this test. They cut much faster than the Kings and seem to induce less apex rounding than the Kings as well, in my experience using them. I'm half inclined to try and figure out a way to get an SPS-II 1k and 3k into your hands to add to the results pool, honestly.

So far, what has really struck me about your testing is that your experiences sharpening 10V on these different abrasives have sounded different from mine with Maxamet. I didn't have the issues with ceramics that you did, and didn't find the waterstones quite as slow to use as you did. It may really turn out to be the case that Maxamet lies just below the VC volume that would cause problems on non-diamond or CBN, while 10V lies above that VC volume? Once you are done with this series of tests it may prove useful to get that blade in 10V into my hands and see if it behaves noticeably differently for me than Maxamet.

 

[HeavyHanded]

I expect to keep doing some testing on this, as it is informative and is helping work the kinks out of my guided widget. I don't know about repeating the test on the Kings or ceramics. I'd have to do something different technique wise that would not be normal - like dosing the surface with some other abrasives, or in the case of the Kings, constantly texturing it as I went.

At a guess I'd say the differences certainly come down to the Vanadium, and possibly the same 10% in Tungsten produces a smaller total volume of carbides as well...anybody?

Of all this, only two things really surprised me.

The chipping I was still getting off of the coarse DMT I did not expect to see.

And on the fine Crystalon it skated over the stone like it was glazed, yet raised a burr with a few moments work and finished with a nice clean edge.

 

[Jason B.]

Im not surprised about the diamond stone chipping the edge at coarser levels given the hardness of the test blade. This is something I've noticed on hard and thin Japanese Kitchen knives when I set or repair a bevel with diamond plates.

Sharpening tungsten rich steels I've noticed that Glassy feeling as the blade moves over the stone, my hap40 blades have a similar feeling. It's definitely a unique feel to tungsten rich steels.

 

[Steel_Drake]

The chipping I was still getting off of the coarse DMT I did not expect to see.

Im not surprised about the diamond stone chipping the edge at coarser levels given the hardness of the test blade. This is something I've noticed on hard and thin Japanese Kitchen knives when I set or repair a bevel with diamond plates.

Oddly, I was having issues with microscopic chipping off my DMT EF, but not off my Atoma 1200 or my DMT EEF on my Mule Team in Maxamet. I haven't used any DMT plates coarser than the EF since I got my Atomas, so I don't know know if I'd have the same issue on a DMT C. I should check that at some point.

 

[BluntCut MetalWorks]

Martin/HH - your excellent works are very much appreciated!

My recent 68rc 10V blades are actually production but I don't have time (nor inclination) to turn many of them into products.

10%W is equiv to around 3.3%V in term of carbide count (+- % depend on actual MxCy form). Also carbide size should taken into consideration (WC is much smaller-avg than VC)

Micro chipping from coarse grit sharpening/apexing and other steel attributes - such as ductility & bending radius (at carbide interface/boundary)... are heavily correlated to binder matrix (whether ferrite/iron; cobalt; mart; aust/ra). Physical & behavior attributes might become apparent by focusing at binder matrix factor.

http://zknives.com/knives/steels/st...HAP40,Rex 121,CPM 10V&ni=,1421,,54&hrn=1&gm=0
https://www.tedpella.com/Material-Sciences_html/Abrasive_Grit_Grading_Systems.htm
https://books.google.com/books?id=pYLjBwAAQBAJ&pg=PA334&lpg=PA334&dq=cobalt+matrix+hardness&source=bl&ots=hfTwV-P5oE&sig=-qtN0S63EsOjqg11bJhjlxXTp5s&hl=en&sa=X&ved=0ahUKEwj964zyp4PRAhWFxlQKHSh8AHgQ6AEITDAJ#v=onepage&q=cobalt%20matrix%20hardness&f=false"

tạm biệt

 

[HeavyHanded]

Martin/HH - your excellent works are very much appreciated!

Not a problem - this is pretty easy compared to retention testing.

My recent 68rc 10V blades are actually production but I don't have time (nor inclination) to turn many of them into products.

10%W is equiv to around 3.3%V in term of carbide volume (+- % depend on actual MxCy form). Also carbide size should taken into consideration (WC is much smaller-avg than VC)

So while still a ton of carbides and a respectable amount of V, the Maxamet has considerably less carbide by volume and much of it smaller than the <3 micron of the 10v VC.

That would make it a lot easier to grind comparatively, even at comparable RC, which as a separate factor only slows grinding down but doesn't really interfere the way carbides do.

 

[BluntCut MetalWorks]

It's the 10%Co matrix, which (I am guessing) is equiv to about 5%Fe matrix (except a few rc higher but still only 20rc). Binder, binder.....

...
So while still a ton of carbides and a respectable amount of V, the Maxamet has considerably less carbide by volume and much of it smaller than the <3 micron of the 10v VC.

That would make it a lot easier to grind comparatively, even at comparable RC, which as a separate factor only slows grinding down but doesn't really interfere the way carbides do.

 

[BluntCut MetalWorks]

before I go stealth/mia ...

5-10% binder in volume is a huge amount... on the extreme a WC tool bit is mostly WC + 5-17%Co, where Cobalt is 100% of binder matrix. In high cv steels, 5% of highly ductitle (Fe/Co/soft-stuff) at particle & mart unit interfaces translate to a much larger influence, since ductility allows plastic & some displacement.

 

[cchu518]

Hey fellas, I just thought I would tack on a question here rather than start a new thread. I just received a knife in S110V steel and saw that a lot of folks recommend aligning the carbides using a diamond paste/strop method. It's that weird steel to me that feels dull yet rips through course material like a hot knife in butter. I've been able to get it toothy sharp and am awaiting for my diamond paste to come in. I'm starting to Ng to believe that S110v is grabby and thats its characteristics, that I shouldn't expect for it to do what it does and to have a refined edge.

The question I have is can diamond paste do the same with D2 tool steel and align the carbides so that it is less toothy and has more of a refined edge if it works in this way does it stay like this for a while?

 

[DeadboxHero]

Hey fellas, I just thought I would tack on a question here rather than start a new thread. I just received a knife in S110V steel and saw that a lot of folks recommend aligning the carbides using a diamond paste/strop method. It's that weird steel to me that feels dull yet rips through course material like a hot knife in butter. I've been able to get it toothy sharp and am awaiting for my diamond paste to come in. I'm starting to Ng to believe that S110v is grabby and thats its characteristics, that I shouldn't expect for it to do what it does and to have a refined edge.

The question I have is can diamond paste do the same with D2 tool steel and align the carbides so that it is less toothy and has more of a refined edge if it works in this way does it stay like this for a while?

You can refine the edge on s110v, its not impossible, its just difficult, most peoples angle inconsistency adds up and rounds the apex rather then polish a crisp edge, microconvexing prevents a treetoping edge

Also, even if you don't round the edge microscopicly, you are still reducing edge endurance and take away the performance of those cemented carbides that you pay all that money for. Besides, a mirror edge is always going to reduce the cutting endurance of the edge no matter what the steel is, of course the trade off being cleaner cuts and more finesse.

I'm coming to find most knives just need the proper balance of polished toothy, with the exception being straight razors, some wood working tools, and certain kitchen knives

The diamond compounds just are just to polish the teeth where the carbides are more exposed embedded in the iron matrix, they don't align the carbides


Also I would nt go crazy with compounds. Just stick with the 1 micron.