Sharpening high hardness and wear resistant steels

[Chris "Anagarika"]

Chris,

Yeah - yours aebl paring is very thin as well (I can't recall in my mind now - lol).

For aebl paring thinnest apex where degradation is by wear, could be 1-2um wide. Of course depend on tasks & technique & pressure, etc..

General DMT C + 1um strop probably produces toothy edge - so longevity hinge on factors ^ above. Sub micron peaks could degrade rapidly and if failure mode is roll/deformation, performance could drop quicker than intended. Having a gut feeling (hahaha by empirical experience) what thinnest apex be - could aim for ideal strop rounding the apex, to ensure edge is no longer in damaging range - i.e. in wear mode. Jason B's has more sharpening experience than I, so producing these kind of edges are probably just an inherent instinct to him :thumbup:

Thanks. The AEBL has 2 mini ripples (on the sharpening bevel) but no chip. It is in line with your discussion on the video. Since it still cuts well, I see no reason to sharpen it out. :thumbup:
The video is a good reminder for me not to always chase clean dry shave. Lol.
Yeah, guessing the apex condition is perhaps what differentiates pro like Jason with his thousands of sharpening that can match the steel (incl. HT), geometry, abrasive, intended usage to produce the optimum result, and obsessed amateurs like me . I'm learning always though.

 

[HeavyHanded]

aaaaaaah not quite so fast . . . I want to know how it does trimming slivers off hard rubber. My 110v could cut hair, whittle hair, catch on hair. Petered out in the real world.

Vid trimming hard rubber or it didn't happen.

had an old wheel chock collecting dust at work, cord reinforced rubber. Jst a quick view cutting through, not sure if this counts or not. I didn't do a before and after on paper or anything, but it held the edge just fine.

[video=youtube;8_W108aEpYU]https://www.youtube.com/watch?v=8_W108aEpYU[/video]

 

[ice-pic]

Well I am impressed by that,tough knife.
I have been cutting Kiwi fruit lately and the knife shines there also.

 

[HeavyHanded]

Well, the initial numbers are in for the King stones on this 10v 68 RC knife.

The initial pressure cut on 3/8" Manila averaged 17lbs - not bad

Initial draw cut was 12 pounds and it could barely do that two out of three - not good

I took some very uninteresting video. I attempted to set the bevel on a guide, then switched to freehand as I needed more feel, speed and pressure.

My impression is that the "facsimile" of a burr I mention in the video is mostly the apex slowly croaking from lateral loading and minimal abrasion, similar to sharpening something like D2 on a hard Arkansas, maybe worse. The abrasion barely keeps up with the lateral forces acting on the apex. It looks like a burr, but as for being the trailing by products of grinding - not exactly.

In all fairness to the King stones, after testing I resharpened on my Suzuki Ya ceramic bound AlumOx stones. While the 1k Suzuki Ya did a fair bit better than the 1k King, it still produced very little in the way of swarf, as did the SY 4k, a stone that normally produces thick streaks of swarf even on high Rockwell stainless and high RC carbon steels are ground with ease. The final edge was not much better than the King result.

Based on this outcome I am going to include a series done on silicon carbide wet/dry. I am not planning to retest the Kings.

[video=youtube;4ENpM0LkFK4]https://www.youtube.com/watch?v=4ENpM0LkFK4[/video]

 

[Steel_Drake]

Well, the initial numbers are in for the King stones on this 10v 68 RC knife.

Would you by any chance have any willingness to try the King 1k and 4k one more time, but flatten them with a diamond plate immediately prior to use and make sure a heavy slurry is always present on the stone (which may require re-lapping the 4k during use)?

It would generate a useful data point on how much of a difference using the same stones very muddy makes on these types of steels. Having myself tried to use the King 4000 without flattening it and without a slurry on Maxamet, I found that the King 4k virtually did nothing at all to the Maxamet that way. Conversely, I found I could get the King 4k to produce the type of apex finish I would normally expect if I used it freshly lapped and with a heavy slurry on it.

 

[BluntCut MetalWorks]

Appreciated :thumbup: Impatiently waiting for your next test

Well, the initial numbers are in for the King stones on this 10v 68 RC knife.

The initial pressure cut on 3/8" Manila averaged 17lbs - not bad

Initial draw cut was 12 pounds and it could barely do that two out of three - not good

I took some very uninteresting video. I attempted to set the bevel on a guide, then switched to freehand as I needed more feel, speed and pressure.

My impression is that the "facsimile" of a burr I mention in the video is mostly the apex slowly croaking from lateral loading and minimal abrasion, similar to sharpening something like D2 on a hard Arkansas, maybe worse. The abrasion barely keeps up with the lateral forces acting on the apex. It looks like a burr, but as for being the trailing by products of grinding - not exactly.

In all fairness to the King stones, after testing I resharpened on my Suzuki Ya ceramic bound AlumOx stones. While the 1k Suzuki Ya did a fair bit better than the 1k King, it still produced very little in the way of swarf, as did the SY 4k, a stone that normally produces thick streaks of swarf even on high Rockwell stainless and high RC carbon steels are ground with ease. The final edge was not much better than the King result.

Based on this outcome I am going to include a series done on silicon carbide wet/dry. I am not planning to retest the Kings.

[video=youtube;4ENpM0LkFK4]https://www.youtube.com/watch?v=4ENpM0LkFK4[/video]

 

[HeavyHanded]

Would you by any chance have any willingness to try the King 1k and 4k one more time, but flatten them with a diamond plate immediately prior to use and make sure a heavy slurry is always present on the stone (which may require re-lapping the 4k during use)?

It would generate a useful data point on how much of a difference using the same stones very muddy makes on these types of steels. Having myself tried to use the King 4000 without flattening it and without a slurry on Maxamet, I found that the King 4k virtually did nothing at all to the Maxamet that way. Conversely, I found I could get the King 4k to produce the type of apex finish I would normally expect if I used it freshly lapped and with a heavy slurry on it.

I'll give it a try using a slice cut from the same stone to raise the slurry. The stones were just flattened, so I'll add some mud and repeat. I have some reticence using this method as I've never seen it improve grinding ability on other steels, and managing a slurry is difficult to quantify, whatever the outcome. But in keeping with the thread I'll give a try and report back.


The next test I'm planning is to reset the bevel on a fine India and refine on the two grades of textured Spyderco ceramic.

 

[Steel_Drake]

I'll give it a try using a slice cut from the same stone to raise the slurry. The stones were just flattened, so I'll add some mud and repeat. I have some reticence using this method as I've never seen it improve grinding ability on other steels, and managing a slurry is difficult to quantify, whatever the outcome. But in keeping with the thread I'll give a try and report back.

Thanks, I appreciate it.

The next test I'm planning is to reset the bevel on a fine India and refine on the two grades of textured Spyderco ceramic.

I'm a little concerned that going from an India F to a Spyderco M may be a bit too large of a grit jump. I'd anticipate you'd need to spend quite a lot of time on the Spyderco M to replace such a coarse scratch pattern. In my own testing I was going all the way up to a ~3-5k waterstone before switching to the Spyderco M to save grinding time (and to guard against some of the dangers of prolonged freehand use of Spyderco benchstones, though you have a guided system so that shouldn't be an issue for you).

 

[HeavyHanded]

I'm a little concerned that going from an India F to a Spyderco M may be a bit too large of a grit jump. I'd anticipate you'd need to spend quite a lot of time on the Spyderco M to replace such a coarse scratch pattern. In my own testing I was going all the way up to a ~3-5k waterstone before switching to the Spyderco M to save grinding time (and to guard against some of the dangers of prolonged freehand use of Spyderco benchstones, though you have a guided system so that shouldn't be an issue for you).

I know, and may have to adjust my plans if it doesn't work out. I'm trying to avoid the ceramics only burnishing an already set edge, so they have to do some of the work of setting that edge AND refine it a bit. If it doesn't work out, I can go back and use the Suzuki Ya 1k, as its still AlumOx but in a much harder binder than the King.

 

[HeavyHanded]

OK, I resharpened the 10v on King 1k and 4k stones, using heavy mud generated with slices cut from the same stones. This time I did the entire thing with the guide, no freehand.

It took about 20 minutes on the 1k, refreshing the mud every couple of minutes, using approx 1 - 1.5 lbs of force for all but the final few minutes of work. There was an improvement in how the stone was able to sharpen the steel, and this was entirely dependent on the presence of mud. It was not a huge improvement, but the influence was unmistakable.

The effect was much more pronounced on the 1k. I spent 40 minutes total on the 4k, diligently working up mud as it was pushed around. After 20 minutes I increased my angle about 1/3 of a degree as it just wasn't making progress at the apex. One stretch of belly on one side of the blade, about 1/8", was slightly more obtuse coming from the 1k, estimate a degree or so (possible the guide rod floated for a few passes ?). The 4k was utterly unable to recover that slight deviation. Even with heavy mud it was all it could do to flatten out the 1k grind marks and shine it up a bit along the edge.

Edge quality was improved based on three finger sticky and ability to crosscut newspaper and paper towel.

Retested on the Inquisitor and it came back with slightly higher numbers on the push but a notable improvement on the drawcut:
18lbs pressure cut
9lbs minimum draw

Overall good numbers. If one had to use these stones on this steel, is possibly the only way to do so. I kept the amount of added water to a minimum when building the mud. Is entirely possible a thick slurry from these stones could be used on frosted glass to better effect, especially on the 4k. Had the impression as I worked that the surface was becoming smoother and the slurry had less and less to grab onto - the rubbing stone just as smooth as the stone itself.

The actual stone surface was contributing very little. In the absence of mud, grinding slowed to a halt and the stone surface was only able to burnish the steel. Best practices would be to use an XC or XXC to build the slurry (as recommended) as this would also have the effect of heavily texturing the stone and improving the bite of unfixed abrasive slurry.

Props to Steel Drake. On to the India/ceramics...

 

[Steel_Drake]

OK, I resharpened the 10v on King 1k and 4k stones, using heavy mud generated with slices cut from the same stones. This time I did the entire thing with the guide, no freehand.

Thank you for taking the time to try out the Kings again. I know running these sorts of tests is a fair bit of work, and I really appreciate it.

Your experience with using them with a heavy slurry corresponds quite closely to the results I was getting using the King 1k and 4k on Maxamet. Since the actual surface of the stones on the Kings still manage to contribute to a greater extent on steels like CPM-M4 at ~62 HRC, you might imagine why I was always so confused when people would say King stones couldn't be used on on M4 type steels, since I always use my waterstones with a heavy slurry on them and hadn't really tried the Kings without a slurry prior to this thread.

Of course, in practice I would use (and do actually normally use) SPS-IIs rather than Kings on these types of steels (if I wanted to use waterstones) since they have a harder abrasive, a much higher abrasive density, and an even lower bond strength, meaning they aren't quite as time consuming and laborious to use as the Kings were.

I'm looking forward to your next update.

 

[Mike DeAmicis]

I'll give you guys three guesses on what I'm about to say, though you probably won't need them.

There is an obvious tool choice for this application that is being overlooked. Sigma Power Select II waterstones are made from silicon carbide with very little binder, and should have no trouble cutting any steel regardless of hardness or wear resistance.

Considering I managed to successfully apex a ceramic knife on an SPS-II 1000, I don't see why it would have trouble 10v.

Thanks for this. A whole lot of enlightenment in a small package.

 

[Wowbagger]

Rubber vid
Thank you
Now once you got some cuts on the edge take it to the block and carve a sliver off in a controlled manner.
For instance I thought I saw the edge fail to bite near the end of the vid so you kept digging in progressively steeper to get a bite (or maybe the edge encountered a previous cut that was another angle and that's why it lost its bite) but what I kept getting with S110V was the edge lost its sharpness and could not take a light curl. It would just skip and grab and skip and grab but not a controlled light sliver. Think fine feather stick kind of curl but consistent thickness not cutting deeper at the end. As if you were just cutting the flashing off a molded rubber part.

Sorry to harp on this. It is just that I do this a lot, M390 can and the "V" steels don't seem to be able to keep a sharp enough working edge . . . in other words they are not high wear . . . and high sharp at the same time.

Maybe I need to experiment with geometry. I am just using similar knives with stock factory edge geometry.

Thanks again for taking the time to post that vid. I don't even ask for another . . . just that you try the lighter cut and let me know how it went. Did it skip and grab , skip and grab (like the edge was giving up) or did it take an even light curl and could you control the depth easily ?

 

[HeavyHanded]

Rubber vid
Thank you
Now once you got some cuts on the edge take it to the block and carve a sliver off in a controlled manner.
For instance I thought I saw the edge fail to bite near the end of the vid so you kept digging in progressively steeper to get a bite (or maybe the edge encountered a previous cut that was another angle and that's why it lost its bite) but what I kept getting with S110V was the edge lost its sharpness and could not take a light curl. It would just skip and grab and skip and grab but not a controlled light sliver. Think fine feather stick kind of curl but consistent thickness not cutting deeper at the end. As if you were just cutting the flashing off a molded rubber part.

Sorry to harp on this. It is just that I do this a lot, M390 can and the "V" steels don't seem to be able to keep a sharp enough working edge . . . in other words they are not high wear . . . and high sharp at the same time.

Maybe I need to experiment with geometry. I am just using similar knives with stock factory edge geometry.

Thanks again for taking the time to post that vid. I don't even ask for another . . . just that you try the lighter cut and let me know how it went. Did it skip and grab , skip and grab (like the edge was giving up) or did it take an even light curl and could you control the depth easily ?

The last strip I cut went very clean. I changed angle and hogged the corner off because I was accumulating some hangers off the edge of the block. If I had been 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, I'd have a lot more control. And then I was trying to shave the thickest slices I could manage without choking, to see how it would do with max (speculation) lateral loading on the apex. It was catching great, felt like I was carving Basswood.

Personally I don't use a ton of high VC steel, but in my experience it holds up to fine edge work better than the high Chromium carbide steels. 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.

At EOD you have to go with what you find works from personal observation, doesn't matter what anyone else says if it doesn't work for you. On rubber, the high wear might not be even much of a bonus.

 

[HeavyHanded]

More testing.

The ceramics did not work well on this knife. Initially I set the edge on an India stone but experienced a fair amount of edge chipping, so switched to my Suzuki ya 1k. Set the bevel and on to the "medium" side of my lapped Spyderco. Was slow going, but it appeared to be promising. However as I got closer to overgrinding the 1k scratch the edge began to chip out.

At first I thought I was revealing some artifacts from the 1k, but as I went it became increasingly obvious it was happening real time. I kept at it, lightening my load to well under a pound, approx 6-8 ozs. Yet, every time I came close to removing the microchips the goal posts kept getting further away and more would form.

Elevated the angle to 17° and switched to the "fine" side of my lapped stone, attempting to microbevel the microchips away, but it was still no use. Slight reduction in rate of chipping but not enough to get a truly clean edge. To the naked eye it looked OK, but at 20x you could clearly see the damage. Having spent close to an hour trying to get this right, I called it. There was swarf in evidence on the stone, so some abrasive action taking place.

I am not comfortable making any definitive statements re this sample, just reporting this is what I did and the result. In my hands this steel at 68 RC is a poor candidate for the low abrasion/burnishing action of fine textured ceramic.

So, got it as good as I could manage and tested it on the Inquisitor, averages:

25 lbs pressure cut

12 lbs draw

compared to what the muddy Kings produced:
18lbs pressure cut
9lbs minimum draw

next test, SiC wet/dry

 

[Steel_Drake]

The ceramics did not work well on this knife.

Thanks again for your continued efforts.

I have a couple of ideas on things you might want to try to isolate what was causing the poor performance on the ceramics, if you are so inclined:

First, do you happen to have a factory Spyderco M benchstone (i.e. unlapped)? That might be worth trying to exclude any effects of lapping your Spyderco F. If you don't have one, and are inclined to try it, I'll mail you mine to use for this test. I also say this because I don't use my Spyderco F benchstone because it behaves very strange and poorly compared to my M and UF benchstones.

Second, did you use the stones dry, with water, or with mineral oil? My experience has been that they work best when used with mineral oil.

Third, you may want to try an even lighter touch. My experience with these stones is that the work better the less force you use. I use mine with more like ~2-3 oz. of force than 6-8 oz.

Fourth, you may want to consider just using a ceramic after a ~3-5k waterstone just to get a crisp apex line, even if it means the ceramic itself isn't doing that much of the work (since the waterstones would also be AlOx anyway).

I'm actually really curious to see how the SiC wet/dry does. As long as you can de-burr the apex effectively, it might put up some interesting numbers.

 

[HeavyHanded]

I don't have a Medium. I have used my lapped stone on a number of knives and have gotten very good if not excellent results off of both sides. Is still possible they are part of the problem, but when I saw the India having trouble even with a light touch I knew I was in for it on the ceramics.

I used them with a thin smear of mineral oil. When switching to the finer side I lightened up as much as I could and still keep contact. I cannot say for sure as I currently have no scale under my set-up, and the guide widget actually supports some of the weight of the knife, but was a very light touch.

I thought about using the waterstones to get a better edge set, but felt if the ceramic couldn't even cut a clean microbevel, it wouldn't be capable of touchups either = not very useful in this application. And then I had already been at it for an hour.

 

[Steel_Drake]

I don't have a Medium. I have used my lapped stone on a number of knives and have gotten very good if not excellent results off of both sides. Is still possible they are part of the problem, but when I saw the India having trouble even with a light touch I knew I was in for it on the ceramics.

I used them with a thin smear of mineral oil. When switching to the finer side I lightened up as much as I could and still keep contact. I cannot say for sure as I currently have no scale under my set-up, and the guide widget actually supports some of the weight of the knife, but was a very light touch.

I thought about using the waterstones to get a better edge set, but felt if the ceramic couldn't even cut a clean microbevel, it wouldn't be capable of touchups either = not very useful in this application. And then I had already been at it for an hour.

Thanks for the further information. I may have to try taking my Mule Team in Maxamet straight from a ~1k stone to my Spyderco M and see how it reacts as a point of comparison.

 

[eKretz]

This pretty much confirms what I've found about this subject - and we covered that in a thread linked to earlier (the old stropping thread). High carbide steels can certainly be cut with AlO or SiC stones at a coarse level, albeit not very efficiently. For instance, I sure wouldn't want to do any heavy reprofiling with one. It's kind of like mowing the grass with a sickle rather than a lawn tractor. It can be done but it's much more efficient and you get a higher quality cut with better tools.

 

[HeavyHanded]

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.