New diamond matrix stone user, micro-chipping?

[Strauss95]

I recently picked up the full set of Edge Pro diamond matrix stones so I could make my Edge Pro system relevant again when sharpening "super steels". I'm a big sharpening nerd so I'd binge watched and read everything I could find about the stones before using them. I also bought Diemaker's stone dressing set of loose abrasives so I had the proper supplies for dressing them. I use the retractable table magnet, slide guide, angle cube, and drill stop collar.

My issue I'm running into is apparent micro chipping on the apex. I have been able to repair and fix the issue after sharpening a second or third time, but seem to be running into the issue on every "first" sharpening of a knife. My process has been as follows....

1. Reprofile edge with 80 grit stone. Keep pressure light, back and forth strokes until I apex and a burr forms.
2. Switch to edge trailing only on the 80 grit, just a few light sweeping passes each side to minimize the burr.
3. Move through the rest of the grits, light pressure, edge trailing only, slight sweeping left to right motion on the downstroke with the stone. 10-15 strokes per side, minimum.
4. Light stropping with bare leather on Edge Pro.

I've been inspecting the apex through the progression with my inexpensive pocket microscope. It was very cheap, but it actually works surprisingly well, 60x magnification. The apex does clean up some as I move up through the grits. I've tried doubling the amount of strokes per side which helped some, but did not remove all micro chips. I've had this problem on most all of my higher end, hard steels. K390, Maxamet, Rex45, etc. Only way I've been able to fully remove them is to do a complete re-sharpening, starting back on the 80 grit.

I've dressed my stones a couple of times with proper loose abrasives, but that didn't change the end result. Since the micro chipping improves each subsequent sharpening, I'm wondering if the reason for the chipping is the much larger burr that is formed on the first sharpening? Since I'm typically reprofiling, naturally the burr gets a bit bigger in certain spots on the apex, even though I try to hit specific areas at a time that still need work. When I sharpen the second and or third time the burr is much smaller on the 80 grit stone since I'm reaching the apex immediately.

Another issue I'd like input on is, I also have noticed I get a cleaner apex if I do only straight "up and down" edge trailing passes. But the scratches on the bevel end up looking "splotchy", not nice and uniform. The end result doesn't look very nice. When I add a slight horizontal sweeping motion the bevel looks very nice with a uniform scratch pattern.

Just wondering if anyone else has experienced these "issues" and can give me some pointers moving forward.

 

[115Italian]

I’m thinking the 80 grit is too aggressive. I always take into consideration the condition of the edger before I start sharpening. If there is a reasonable edge on it still, there’s no reason to go that low in grit.

 

[Obsessed with Edges]

Same thought as above.

I'd see no reason at all to use an 80-grit stone - not even for reprofiling. Stones that coarse are known for causing chipping issues with some steels. And cracks that propagate from the chips will lead to even more chips & fractures after the fact.

Alternatively, some will use a very coarse stone for reprofiling, but will stop short of fully apexing the edge with it. That way, the risk for chipping the thin edge is lessened. Apex the edge with one of the subsequent, less coarse stones instead.

 

[Strauss95]

I was surprised how "hard" my Rex45 Military felt on the stones. It took about 45min to reprofile the edge down to 16 degrees per side with the 80 grit stone. I would have been grinding away for hours if I was using the 250 grit instead. The Rex45 was second only to Maxamet in grinding difficulty. I tried starting over with the 80 grit once as an experiment, but the rest of the second or third sharpening's I started with the 250 grit stone since the profile was already set. I also tried starting with the 650 once grit but it wasn't aggressive enough to remove the micro-chips. I've been trying different stones, strokes, etc and checking progress with the pocket microscope.

I am really leaning towards the problem being the burr growing too large from reprofiling, and taking pieces of the apex with it when breaking off.

I experimented with back and forth strokes up though the 1100 grit stone as well, but think I got better results with edge trailing only once I reached the apex. The chips I'm dealing with are indeed extremely small, only visible with the pocket microscope. Some of them are big enough to hang up when trying to slice phone book paper testing the edge.

Also just wanted to note I'm only running into this issue on super steels and the diamond matrix stones. When sharpening more "basic" steels I use Chosera stones and don't see any micro-chipping.

I also have been working on my freehand skills and haven't ran into the micro-chip issue there either. That is using either diamond plates, or Venev stones on super steels too. But I spend more time on each grit due to my lack of skills compared to the Edge Pro, so maybe I'm grinding the chips out in the process.

Hoping Diemaker will chime in, maybe he has seen this in his testing?

 

[stonemedusa6264]

Not sure about edge pro stones but using them might help knock off random diamonds that are sticking out too much. It's been awhile since I lapped my stones but I did several less important knives before I did anything I wanted really nice. I don't have a microscope but I like removing the bur and finishing with light leading edge strokes. When I think about it I imagine the abrasive pushing the apex material into the stronger blade or pulling it out into nothing. The one way is pressure against reinforced metal the other there is pressure pulling away from the strong part. To me trailing edge is more likely to tear off apex or make a bur. I have nothing at all to backup this statement but it's how I think about it. Without stropping I can shave and they cut paper not hanging up anywhere. For a working edge at f400 it's fine. If I go for a polish I can whittle hairs without stropping.

 

[Strauss95]

Not sure about edge pro stones but using them might help knock off random diamonds that are sticking out too much. It's been awhile since I lapped my stones but I did several less important knives before I did anything I wanted really nice. I don't have a microscope but I like removing the bur and finishing with light leading edge strokes. When I think about it I imagine the abrasive pushing the apex material into the stronger blade or pulling it out into nothing. The one way is pressure against reinforced metal the other there is pressure pulling away from the strong part. To me trailing edge is more likely to tear off apex or make a bur. I have nothing at all to backup this statement but it's how I think about it. Without stropping I can shave and they cut paper not hanging up anywhere. For a working edge at f400 it's fine. If I go for a polish I can whittle hairs without stropping.

Appreciate the input. The diamond matrix stones are unique in that they work best with edge trailing strokes. The maker, who posts on here often, actually instructs edge trailing ONLY for the last two stones in the line up (2300 and 4000 grit).

Like yourself, prior to getting the diamond matrix stones, I always used light pressure edge leading strokes for burr removal. The diamond matrix stones are indeed a different animal.

If I didn't have the microscope I'd have no idea the micro-chipping was an issue. It should also be noted that it's not noticeable in "actual" knife use, it's just me being a crazy knife nerd. I'm just trying to figure out what is causing this problem for me. At first I just thought it was the aggressiveness of the lower gits, but when looking at Diemaker's images he posted on S90V I saw his apex was MUCH cleaner than mine throughout the entire progression. That's when I realized I was having an "issue".

 

[Wandering_About]

Sharpening all the way to the edge has caused some edge issues for me on reprofiles with an Atoma 140. I do my best now to just take the scratch pattern to just not quite to the edge and work the bevel down to an apex with nothing more coarse than a 400 grit stone.

Seems to me that a super coarse stone can cause some kind of fatiguing of the steel at the edge that can show up as microchipping later on if that affected steel is not fully removed. This seems especially true when I work up a burr with a very low grit stone. My theory is that flexing of the steel at the burr and apex causes the fatiguing and on a low grit stone it creates large enough areas of fatigue that it ends up showing up as microchipping. I've not had issues with 400 grit stones, but things can really show up with my Atoma 140 diamond stone. Using very light pressure helps, but I've found apexing with a bit finer stone works better for me, and I'm usually going to 800-1000 grit to finish an edge anyway.

 

[Strauss95]

Sharpening all the way to the edge has caused some edge issues for me on reprofiles with an Atoma 140. I do my best now to just take the scratch pattern to just not quite to the edge and work the bevel down to an apex with nothing more coarse than a 400 grit stone.

Seems to me that a super coarse stone can cause some kind of fatiguing of the steel at the edge that can show up as microchipping later on if that affected steel is not fully removed. This seems especially true when I work up a burr with a very low grit stone. My theory is that flexing of the steel at the burr and apex causes the fatiguing and on a low grit stone it creates large enough areas of fatigue that it ends up showing up as microchipping. I've not had issues with 400 grit stones, but things can really show up with my Atoma 140 diamond stone. Using very light pressure helps, but I've found apexing with a bit finer stone works better for me, and I'm usually going to 800-1000 grit to finish an edge anyway.

Sounds like the same problem I am running into when working up a large burr reprofiling with the 80 grit diamond matrix stone. My only worry is not knowing when is the right time to stop with the 80 grit, without having to spend too much time on the 250 grit? I suppose that will just come from trial and error, and keeping a close watch with the microscope.

 

[Wandering_About]

Sounds like the same problem I am running into when working up a large burr reprofiling with the 80 grit diamond matrix stone. My only worry is not knowing when is the right time to stop with the 80 grit, without having to spend too much time on the 250 grit? I suppose that will just come from trial and error, and keeping a close watch with the microscope.

I usually just check with a little 10x hand loupe and stop when the scratches from the 140 are just about to touch the edge. My view is it's better to spend a little extra time on an intermediate stone than to have to fix a bad edge later on.

 

[Strauss95]

I was surprised when I first noticed the micro-chips from the diamond matrix stones, especially since I was expecting them to finish even better than my other diamond stones. Besides possibly developing too large of a burr when reprofiling, I also don't spend that much time with each subsequent stone after. Reason being I was trying to follow Diemaker's suggestion of about 10 strokes per 3" of blade length, although I was doing closer to 15-20 probably.

I wish I could get a more consistent scratch pattern on the bevel itself when doing only vertical edge trailing strokes. The bevel ends up looking like crap when doing so, looking all patchy and uneven, even though I overlap my strokes to ensure full coverage. I have to include a slight sweeping motion left to right when edge trailing to get a smooth, even looking bevel. Or maybe applying some pressure may help in that scenario? I've been keeping my pressure very light with the DM stones after I used too much my first go around with the 80 grit. I dressed it with 20 grit aluminum oxide loose abrasive on a ceramic tile I picked up specifically for that purpose. I've been paranoid that the slight sweeping motion was contributing to the micro-chipping, but they may be completely unrelated.

 

[DeadboxHero]

Cut the 80 grit edge off by running it into the next stone in your progression.

 

[old4570]

80 grit is great if you need a new bevel on a hard knife !
But once that bevel is formed , there is no need for it unless your after a 80 grit edge . ( That 80 grit will leave deep gouging ) you might consider moving to 120 before the apex is 100% and then 180 .

Once you have a nicely formed bevel , then maybe 320 grit diamond to clean up with . And for a more refined edge maybe 600 or 800 grit diamond ..
At which point you should be considering bur removal .

I have a decent collection of diamond stones / inserts for my guided knife sharpening . ( 80 - 120 - 180 - 240 - 320 - 600 - 800 - 1000 ) Oxid as well some hard oil stones ..

 

[Strauss95]

Thanks for the input everyone! DeadboxHero By "cutting the edge off" I assume you mean in the same way I'd do that before freehand sharpening to remove the old edge? By directly, lightly slicing into the stone a few times with the edge?

 

[Diemaker]

Strauss95 - Try raising the angle by .1 degree or so, or about .02", and take a few light passes with your last stone covering no more than 1" to 1-1/2" of blade with each stroke. This is to make sure that the last stone is reaching the apex. With really hard steels, or ceramics, the coarsest stones tear the apex off leaving a blunt flat face. ToddS posted an image of a straight razor that he sharpened with a 600 grit plated diamond stone that clearly showed this. If all you do with subsequent stones is polish the bevel then you can end up with what looks like a sharpened knife but not exactly sharp, because it is so hard to remove enough steel with the finer stones to refine the apex. This is something that I always do now when sharpening.

Yes, the act of scratching material off of a surface will do some damage. The rule of thumb is to remove twice as much material with your current stone as the deepest scratch from the last stone. ToddS did a blog on this and surmised that the micro-fractures in the steel extended below the scratch about as much as the depth of the scratch. I would assume this will change with the material being scratched and how sharp the abrasives are but could very well be wrong.

The Matrix 80 is probably the least aggressive 80 grit diamond stone there is. The bond makes a huge difference in how a stone cuts and resin is the least aggressive bond. This is not good for hogging but it is good for finishing, as it doesn't do as much damage to the steel since it doesn't dig in as deep, very little of the diamond crystals are exposed. I like it and am not shy about using it to set the bevel on a knife that is rather dull. It is way better to start with a bit too coarse of a stone than one that is not coarse enough, you have to set the bevel first before anything else. I try to just reach the apex with it and nothing more. I would rather miss a spot than remove more metal than needed.

Should your passes be perpendicular to the apex or with some angle? Knives are the only tools I know of where perpendicular to the apex passes is not the only direction used. I don't cover more than around 1-1/2" of blade with a 6" stone per pass, probably closer to 1". I worry that the more angle to my passes the more likelihood of microchipping, but this is more of a gut feeling than anything else. The gut feeling comes from grinding and using cutting tools from and for many different materials for about 35 years.

That fine apex is not stiff steel but a wet noodle. Think of filing an edge on thin metal, say flashing. If you use edge leading the file will catch the edge and pull it up causing all kinds of trouble. Edge trailing passes will be smooth but leave more burrs. With diamond and hard steel those burrs are so small they are not an issue, they are easily removed with a strop of some sort. I think this way of removing the burrs does the least damage to the apex, leaving a keener edge. The last thing I want to do is to finish sharpening an edge by pushing the burr into it.

I think ToddS's blog on edge trailing vs edge leading passes is well worth reading, like all of his blog posts.

 

[Strauss95]

Thank you for the input D Diemaker In regards to raising the angle, is that after I apex with the 80 grit or just the last stone I am finishing on?

Also, have you ran into the issue of uneven scratches on the bevel from pure vertical edge trailing strokes? Where the bevel ends up lookin blotchy or patchy? I find I need to sweep the stone a little bit in order to get a uniform finish on the bevel itself. Or could that be a problem of using too little pressure (my pressure is very light)? Like I said, I overlap the passes for sure to try to eliminate that but it doesn't seem to be working. FWIW I also see this same effect with other stones, not just your diamond matrix.

When I do the slight sweeping, edge trailing strokes, I'm moving about 1/2" horizontally. I find that's all it takes to clean up the scratches on the bevel.

 

[Diemaker]

Thank you for the input D Diemaker In regards to raising the angle, is that after I apex with the 80 grit or just the last stone I am finishing on?

Also, have you ran into the issue of uneven scratches on the bevel from pure vertical edge trailing strokes? Where the bevel ends up lookin blotchy or patchy? I find I need to sweep the stone a little bit in order to get a uniform finish on the bevel itself. Or could that be a problem of using too little pressure (my pressure is very light)? Like I said, I overlap the passes for sure to try to eliminate that but it doesn't seem to be working. FWIW I also see this same effect with other stones, not just your diamond matrix.

When I do the slight sweeping, edge trailing strokes, I'm moving about 1/2" horizontally. I find that's all it takes to clean up the scratches on the bevel.

I change the angle after the last stone. When I sharpen I don't worry about the apex much except for the first stone, and I don't worry about burrs, I just make sure the bevel is getting done. Once I am done with the last stone I wish to use then I raise the angle a bit and use the last stone again to make sure the apex is refined, then strop with diamond to further refine the apex and finally with bare leather to remove any burrs.

I don't get uneven scratches or blotchy/patchy bevels but that may have something to do with my sharpener. Every design element on it is about stability and repeatability.

The rest of my post got lost when I tried posting it but the forum software was updating, and I can't remember what it was.

 

[Strauss95]

I change the angle after the last stone. When I sharpen I don't worry about the apex much except for the first stone, and I don't worry about burrs, I just make sure the bevel is getting done. Once I am done with the last stone I wish to use then I raise the angle a bit and use the last stone again to make sure the apex is refined, then strop with diamond to further refine the apex and finally with bare leather to remove any burrs.

I don't get uneven scratches or blotchy/patchy bevels but that may have something to do with my sharpener. Every design element on it is about stability and repeatability. The only issue that light pressure may raise is

I will finish this later. It was complete but when I tried to post it the site was upgrading, and it lost some of my post.

Standing by for the rest!

I only get the wonky looking bevels with edge trailing strokes that have zero movement of the stone left or right. I assumed overlapping my passes would solve that, but the only fix I've seen is introducing some left or right sweep during the stroke.

 

[stonemedusa6264]

diemaker is todds the guy behind science of sharp? I've been slowly working my way through that website. I don't see any post specifically about leading vs trailing tho. There's stuff about it mixed into other posts. I'm not against edge trailing. I could never find anything definitive on it and got good results with edge leading. It is interesting to see what's happening at that level of magnification.

 

[Strauss95]

diemaker is todds the guy behind science of sharp? I've been slowly working my way through that website. I don't see any post specifically about leading vs trailing tho. There's stuff about it mixed into other posts. I'm not against edge trailing. I could never find anything definitive on it and got good results with edge leading. It is interesting to see what's happening at that level of magnification.

I believe you are correct. I'm willing to follow Diemaker's suggestions because I know he meticulously tests his stones and is very detail orientated, which I greatly appreciate. His willingness to offer support and to help others with the use of his product is the reason I bought his diamond matrix stones instead of the Venev's for my Edge Pro. I'm very satisfied with my full size Venev bench stones, which I've owned for almost 4 years now, but his helpful insight made all the difference for me when it came to buying stones for my EP. Mad respect.

 

[stonemedusa6264]

I'm still open to changing it but stuff like science of sharp n images like that weren't available when I found my style. I did step away from looking for more info cause I didn't find anything new or definitive in so long. I'm glad the knowledge base is progressing.

I found science of sharp about a month ago. Who knew carbide tear out wasn't a thing? I never heard anyone saying I micro bevel with a chosera to expose more carbides in the cutting edge. All the talk when I was getting into super steels was about carbide tear out, but it appears this doesn't happen. Like at all. You can shatter them with diamond stones though so thats great. I like one of the last things I read on there earlier. Someone asked him what the results meant. He said that they go against all current thoughts on the topic and he'd rather just let it stand for now.