You all ruined my Worksharp!

[Doug C]

I was going to say..
How sharp do you want your knife to be ?
How often do you want to re-sharpen ?

..but your post below cleared that up ! :thumbup:

My knives are hardly users.

DC

 

[dkb45]

I was going to say..
How sharp do you want your knife to be ?
How often do you want to re-sharpen ?

..but your post below cleared that up ! :thumbup:



DC

What I would love to have is so sharp I can cut the fabric of spacetime, but I will have to settle for push cutting tissue paper.

 

[awestib]

I'll scare up one of my pieces of Flexcut and take a closer look on Tues - have a high powered microscope at work. I break down some of the compound on a clean slide with mineral oil and see what shakes out. If it looks strange I repeat this a few times. Have gotten very consistent results in the past and was able to determine the average abrasive size of several compounds with reasonable accuracy.

I've already done this with the Formax microhoning compound and Ryobi white and black, as well as a handful of others, have never done this with Flexcut.

Martin - time to release a "grand unified compound analysis chart" based on your findings. That would help us all a lot and it could be a sticky !!

 

[awestib]

Personally I avoid using oils on leather strops unless I'm reconditioning it and the leather really needs some help. In that case I'd stick with products made for leather. You run into situations where there's too much mobility of the abrasive and it stops working properly. This applies to paper and when using hardwood lapping boards as well, but is a lot more forgiving in those applications relative to leather.

You can rub a few drops of mineral oil into the block of compound and apply that way, or just press hard and make a grid across the surface. I used to keep my compound in a baggie with a few drops of oil, give it a shake and the entire surface of the block will soften a little and go on a lot easier.

i've done that (zip lock bag with a bit of mineral oil as a storage for the BRKT black compound) and it works great.

 

[Chris "Anagarika"]

Andy, Martin,

Similarly I store the black stone like compound and when using, rub some oil to it and apply to paper :thumbup:

 

[dkb45]

Ok new problem. I am very careful with my sharpening, but I am getting pretty bad micro chipping on the edge. My edges are also just not that good compared to how they should be even though I am keeping angles right and I am keeping pressure right. The edges are rounding slightly, but the issue I am getting is a terrible polish on the edge. Tons of really deep scratches that are just not coming out from my most coarse sandpaper.

 

[HeavyHanded]

Martin - time to release a "grand unified compound analysis chart" based on your findings. That would help us all a lot and it could be a sticky !!

Andy, I only have pics of two compounds at the moment - I'd better get hopping!

 

[HeavyHanded]

Ok new problem. I am very careful with my sharpening, but I am getting pretty bad micro chipping on the edge. My edges are also just not that good compared to how they should be even though I am keeping angles right and I am keeping pressure right. The edges are rounding slightly, but the issue I am getting is a terrible polish on the edge. Tons of really deep scratches that are just not coming out from my most coarse sandpaper.

Couple of thoughts, the microchipping might be that you're revealing the ends of the grind troughs from the coarser scratches you mention. The cutting line can sometimes appear to get more irregular for a few as you work these out.

Keep the paper tight on whatever surface is the backing, stay on it with the light pressure and frequent cleaning, and add more progressions. Was a time if I wanted to make certain I had done a good overgrind from a rougher finish, I'd raise and remove the burr twice before moving to the next progression.

 

[Chris "Anagarika"]

Ok new problem. I am very careful with my sharpening, but I am getting pretty bad micro chipping on the edge. My edges are also just not that good compared to how they should be even though I am keeping angles right and I am keeping pressure right. The edges are rounding slightly, but the issue I am getting is a terrible polish on the edge. Tons of really deep scratches that are just not coming out from my most coarse sandpaper.

Imagine the steel surface as being scratched = valley being made, it means to remove deep scratches = remove everything else to level down to same level as the valley bottom.
Light pressure is used to ensure the next finer grit only abrade the peak and not deepending the valley, and so on.

Hope this is helpful. I have some deep scratches from coarse dmt when I have yet understand how deep diamond can dig, that I leave it as it is rather than removing too much metal.

It also explain what Martin describes: the microchip might be the valleys going full to the edge apex.

 

[dkb45]

I looked under the loop (10x) and most are just on the edge. I have been doing passes on the sandpaper with moderate through to light pressure on each grit (using each grit kind of as a progression in itself). Does the "only on the edge" micro chipping mean I am using too much pressure? It can't be diamonds contaminating the paper, I have been careful on cleaning.

It would be great if any of you guys weren't across the bloody country to give me pointers in person. Seeing my technique is the easiest way to figure out what I am doing wrong.

 

[Obsessed with Edges]

I looked under the loop (10x) and most are just on the edge. I have been doing passes on the sandpaper with moderate through to light pressure on each grit (using each grit kind of as a progression in itself). Does the "only on the edge" micro chipping mean I am using too much pressure? It can't be diamonds contaminating the paper, I have been careful on cleaning.

It would be great if any of you guys weren't across the bloody country to give me pointers in person. Seeing my technique is the easiest way to figure out what I am doing wrong.

What steel are you sharpening? And what grit of sandpaper are you using right now, with what backing under the paper? If this is the S30V mentioned in your original post, you may be seeing the difficulty of removing the coarser grit scratches with the SiC/AlOx of the paper. At finer grits, the limitations of the abrasive make it much more difficult to abrade the vanadium carbides in S30V. At coarser grits, the carbides just get plowed out of the softer matrix steel holding them, so their hardness doesn't impact it as much at that stage. At finer grits, the sandpaper will have to start abrading the carbides themselves (shaping them), to make a significant difference at the edge. Neither SiC nor AlOx will be hard enough to do that very well, if at all.

I'm bringing this up, because these are the exact same issues (see bolded and underlined text below) that limited my own efforts in trying to use SiC sandpaper to refine S30V past a certain point. Firmly affixing sandpaper to a very hard backing, like glass or smooth stone, can help it dig a little more aggressively, but the abrasive can only do so much. Diamond works much, much better at the refining stages on S30V and similar steels with high vanadium carbide content.

Ok new problem. I am very careful with my sharpening, but I am getting pretty bad micro chipping on the edge. My edges are also just not that good compared to how they should be even though I am keeping angles right and I am keeping pressure right. The edges are rounding slightly, but the issue I am getting is a terrible polish on the edge. Tons of really deep scratches that are just not coming out from my most coarse sandpaper.

David

 

[dkb45]

What steel are you sharpening? And what grit of sandpaper are you using right now, with what backing under the paper? If this is the S30V mentioned in your original post, you may be seeing the difficulty of removing the coarser grit scratches with the SiC/AlOx of the paper. At finer grits, the limitations of the abrasive make it much more difficult to abrade the vanadium carbides in S30V. At coarser grits, the carbides just get plowed out of the softer matrix steel holding them, so their hardness doesn't impact it as much at that stage. At finer grits, the sandpaper will have to start abrading the carbides themselves (shaping them), to make a significant difference at the edge. Neither SiC nor AlOx will be hard enough to do that very well, if at all.

I'm bringing this up, because these are the exact same issues (see bolded and underlined text below) that limited my own efforts in trying to use SiC sandpaper to refine S30V past a certain point. Firmly affixing sandpaper to a very hard backing, like glass or smooth stone, can help it dig a little more aggressively, but the abrasive can only do so much. Diamond works much, much better at the refining stages on S30V and similar steels with high vanadium carbide content.


David

The steels it is happening to are D2 (Bionic), Elmax (801), and S30V (700). Surprisingly, M390 (Barrage) came out really crisp with only a handful of deep scratches and no micro chips at all. I really thought SiC could abrade the vanadium carbides, but I am so over my head with all of this stuff my information is getting really jumbled up.

I guess that leads me to another question... are there diamond stones that match or exceed 2000 grit sandpaper? I know about the DMT XXF stone, but a lot of people who used it said it did not produce an edge as good. I think I may just have to suck it up, bite the bullet, and splurge for a full range of DMT stones from XC to XXF.

 

[dkb45]

Looking up DMT stones, I am torn. I want to get a set of diamond stones, but I can get another belt sander. My belt sander was awesome while I had it, but I also didn't have steels like Elmax and M390 when I had my belt sander. The majority of the belts I can find are AlOx, which I know doesn't do a whole lot to vanadium carbides. I did a bunch of S30V blades, and did do one S60V and Elmax blade and all came off my belts razor sharp with an edge as good as I could get with any steel (no micro chips or deep scratches), but I don't know if I was weakening the vanadium carbides.

I'm sorry about being all over the place. I am liking manual sharpening, but it just can't hold up to a belt sander, especially with what I learned from owning and using my Worksharp. The skills acquired from the Worksharp are mostly lost on sandpaper and stones, but almost 100% applicable to a belt sander.

That said, if I did get a belt sander, would I be best off (pertaining to high vanadium steels) to get a set of SiC belts and reserve them specifically for those steels, or would AlOx be fine? It worked before, but like I said, I could have just set those edges up to be almost entirely ripped off... or I could have just made a sharp knife and I am worrying about nothing. I worry about nothing a lot.

 

[HeavyHanded]

The steels it is happening to are D2 (Bionic), Elmax (801), and S30V (700). Surprisingly, M390 (Barrage) came out really crisp with only a handful of deep scratches and no micro chips at all. I really thought SiC could abrade the vanadium carbides, but I am so over my head with all of this stuff my information is getting really jumbled up.

I guess that leads me to another question... are there diamond stones that match or exceed 2000 grit sandpaper? I know about the DMT XXF stone, but a lot of people who used it said it did not produce an edge as good. I think I may just have to suck it up, bite the bullet, and splurge for a full range of DMT stones from XC to XXF.

You can use the sandpaper up to about 800 grit on the higher VC steels, and after that you're better off switching to some 3M diamond lapping films. Can be had for $6 a sheet for the 6" squares in sizes down to sub micron. If you are doing a lot with these steels you probably should get some diamond plates.

 

[Obsessed with Edges]

The steels it is happening to are D2 (Bionic), Elmax (801), and S30V (700). Surprisingly, M390 (Barrage) came out really crisp with only a handful of deep scratches and no micro chips at all. I really thought SiC could abrade the vanadium carbides, but I am so over my head with all of this stuff my information is getting really jumbled up.

I guess that leads me to another question... are there diamond stones that match or exceed 2000 grit sandpaper? I know about the DMT XXF stone, but a lot of people who used it said it did not produce an edge as good. I think I may just have to suck it up, bite the bullet, and splurge for a full range of DMT stones from XC to XXF.

2000 grit sandpaper is about ~10µ particle size (FEPA-P grit standard). I've found both of DMT's EF (9µ) and EEF (3µ), and stropping with diamond paste down to 3µ and lower, to work very well in refining edges taken beyond the 2000 grit sandpaper in finish. You could also likely get away with just utilizing the EF, then refining with 3-1µ pastes on wood strops, for a very high polish on S30V. The vanadium carbides in S30V are ~2-4µ average size, so there's a noticeable difference in ease of refining & polishing S30V's edges when you get to the EF diamond and finer. In particular, the 3µ diamond paste produces a BIG jump in polish, assuming the edge has already been refined enough to be ready for it (thru EF).

SiC is something like 10-15% less-hard than vanadium carbide, and AlOx (alumina) is ~25% less-hard. Conversely, diamond is 2.5X-3X as hard as vanadium carbide, which is why it works so much better at grinding & refining the carbides themselves. There's sort of an illusion about grinding high-VC steels using SiC or AlOx, in that it can work at coarser grits (HH mentions up to about ~800 grit; that seems about right), because the carbides are essentially being plowed or scooped out whole from the softer surrounding matrix steel. The illusion is in assuming the carbides themselves are being 'ground' at that level, because the steel is being successfully ground; but that isn't what's actually taking place. I picture it like using a garden trowel made of aluminum (think: soft 'abrasive') to scoop rocks ('carbides') out of the dirt ('matrix'). Works fine for that, but not-so-good if you're trying to actually grind or shape the rocks with the trowel, instead of just dislodging them whole and moving them out of the way.

BTW, the SiC sandpaper will still work on D2. It has no vanadium carbides to speak of, but instead has chromium carbides. Still pretty hard, but well within the capability of both SiC and AlOx. Both work great on D2.


David

 

[dkb45]

So what I am hearing is that even though I love belt sanders, they are not good for high carbide steel? If so, that sucks. That kind of makes me hate vanadium carbides.

What's weird about sandpaper apparently not being able to abrade vanadium carbides is that my S30V blade has the least micro chipping. My D2 blade has the most, and I was the most careful with it. It's like my knives are purposefully doing random crap to leave me completely confused. Maybe storing them all in the same container was a bad idea because they can now cooperate and plan.

 

[Andy the Aussie]

I just bought extra belts in different grades for the WSKT...

I LOVE sharp knives...I love pretty edges... I love using VERY sharp knives.... BUT for the vast majority of working knives (that are not used for a specialist application) the hair witling sharp thing (I do love it BTW) is purly for, as we say here, wank value.

 

[Obsessed with Edges]

So what I am hearing is that even though I love belt sanders, they are not good for high carbide steel? If so, that sucks. That kind of makes me hate vanadium carbides.

What's weird about sandpaper apparently not being able to abrade vanadium carbides is that my S30V blade has the least micro chipping. My D2 blade has the most, and I was the most careful with it. It's like my knives are purposefully doing random crap to leave me completely confused. Maybe storing them all in the same container was a bad idea because they can now cooperate and plan.

Powered grinders will have some better luck, due to the velocity, but will generate more heat with AlOx belts (as usually used) for sharpening high-carbide steels. A lot of manufacturers often recommend CBN belts (or wheels) for grinding steels like these. CBN is 2nd to diamond in hardness, but is less prone to damage caused (by heat) that diamond would otherwise be subjected to, and it'll cut high-wear steels more efficiently, with less heat generated by friction. That's the biggest drawback with diamond specifically, and most mfrs recommend against using it for powered grinding applications on ferrous metals, because the diamond breaks down under extreme heat, and it's carbon content also reacts in unpleasant ways with ferrous metals (containing iron, in other words), when heated to such levels.

Regarding the 'micro-chipping', I'd bet there's not as much true chipping (i.e. fracturing) going on, as you might think, if any. It usually takes a combination of very high hardness of the blades (60+ HRC) and very hard abrasive media (such as diamond on hard hones) to do that. More than likely, what you're seeing is remnants of coarse stage sharpening scratches that haven't been fully removed all the way to the apex. That would be a lot more common in situations like this, and it's more common when using sandpaper that isn't solidly affixed to a hard backing. The 'give' of the paper, by it's own free movement over the backing, will make it more difficult to aggressively scrub away the coarse scratches left on the edge. This is something that I noticed early on, in using sandpaper wrapped around one of my leather-on-wood strop blocks; it was very difficult to fully refine the scratch pattern all the way out to the apex. Affixing the paper over glass, with adhesive, makes it perform more like a stone, and it's much easier to refine scratch patterns when used that way, more so on high-wear steels like D2 and up.


David

 

[dkb45]

I wrap my sandpaper around a deep bucket paint stirrer, folds nice and creased to make it fit pretty tightly. The paint stirrer is a hard enough enough wood (I think pine) so there shouldn't be anything that would happen with a soft backing like leather or a mouse pad. I'm pretty sure that what I am getting happening is unusually deep scratches from my diamond stone that aren't being taken out by my sandpaper. I visually inspect the edges after every grit, and off the XC my edges are clean looking, with no apparent deep scratches. It could also be that the burr is being ripped off by the coarse sandpaper, because I don't work it down on the low grits (sub 800), I just work a burr on both sides and then move up.

 

[HeavyHanded]

Regarding the 'micro-chipping', I'd bet there's not as much true chipping (i.e. fracturing) going on, as you might think, if any. It usually takes a combination of very high hardness of the blades (60+ HRC) and very hard abrasive media (such as diamond on hard hones) to do that. More than likely, what you're seeing is remnants of coarse stage sharpening scratches that haven't been fully removed all the way to the apex. That would be a lot more common in situations like this, and it's more common when using sandpaper that isn't solidly affixed to a hard backing. The 'give' of the paper, by it's own free movement over the backing, will make it more difficult to aggressively scrub away the coarse scratches left on the edge. This is something that I noticed early on, in using sandpaper wrapped around one of my leather-on-wood strop blocks; it was very difficult to fully refine the scratch pattern all the way out to the apex. Affixing the paper over glass, with adhesive, makes it perform more like a stone, and it's much easier to refine scratch patterns when used that way, more so on high-wear steels like D2 and up.


David

^ This - I cannot imagine anything OP is doing that would lead to the creation of chips, is most likely left over remnants of rougher grind patterns. One of the reasons I stopped using wet/dry until I came back and tried it on my Washboard. It can be very difficult to tell visually if you've truly done a compete overgrind unless using it on the very hardest of surfaces, especially on V ground bevels - is why I mentioned doing multiple burr creation/removal per grit to be thorough. I even went as far as cutting down bonded back SiC belts and gluing them to brass plate, but at that point the cost takes a sharp turn relative to longevity.