Curved sharpening stones

[mzzj]

I kinda meant that at some point, some houses will warp and doors will stick. Or did we solve that with some kind of free-floating door frame? 

At least in here sticking doors are pretty much thing of the past.  40 year old garage door needed adjustment on hinges to compensate for wear but that's about it.
Doorframes and doors also come in standard sizes with pre-machined cutouts for locks and striker plates.  (or even assembled with hardware) 

It's either +50 years old building or something gone silly if construction workers/joiner-carpenter needs a chisel.

[ebastler]

I kinda meant that at some point, some houses will warp and doors will stick. Or did we solve that with some kind of free-floating door frame? 

That's what builders' foam is for (at least over here). 
The official license to botch...

[eKretz]

Hmmm. Ok. Lemme try a logic game.

If you assume that this particular tool (i.e. soft ark) is best-suited to this particular niche (i.e. shiny up a bevel, add a microbevel, or cheesegrate/lap-it-to-get-it-to-work-almost-as-well-as-way-better-alternatives-but-use-it-anyway-because-of-tradition) which we have put it in, presumably due to all the new and shinier (and cheaper and/or more profitable?) tools which have been added to our arsenals since at least 1908 or earlier, you might be getting shortchanged.

Is this even the traditional way to use it? Or did we invent this practice/methods for some other reason? Such as the invention of the diamond saw making perfectly flat and very nearly rectangular slabs of this stone the easiest way to produce them? Perhaps the first generations to buy these perfect slabs, maybe they immediately "fixed them?" Then a generation of humans grew more fond of the "new car shape" than they had need for this tool to actually be effective?  By this time, synthetics might have taken over the market, and these stones might have started to be shelved, anyhow? Or become collector's items?

While the true craftsmen in Solingen Germany quietly continue to find this stone to be one of the best tools for hand-sharpening despite all the new and shiny? 

Despite the time I invested into the fancy wood mounting systems I made, mine are not collector items. Everything there is for utility, once I figured out that these ARE going to be my main method of sharpening, due to being actually more practical for me, all told (well, to be more specific, I mean for blades which require to maintain very keen edges; this method is incredible for maintaining a keen and durable edge, all by its lonesome. Amazing. Not that it makes a sharper edge than other methods). I have used my india only twice in the last 2 years. To sharpen drill bits, and to sharpen a friend's brand new knife that came with no edge. The bits I added were added to get the right height/grip, add utility with the endcaps, clamping points, ergos, et al. That was kinda satisfying in itself; it felt like it was in my DNA to haft stone to wood, like pre-humans have done for like 1 million years or something like that. 700K maybe? I forget what the stone age was.

Err, that has not much to do with my short statements. For final edge work, a translucent or black Ark is the tool of choice. And yes they have been used that way since they came out of the ground via mining probably the very first time. That's their purpose. And it's because the stone is so hard and dense that it can't really do a lot of cutting. If you lap it very coarsely it will cut faster but it will rapidly dull and the stone is so hard that the dull grit doesn't get removed, it just sits there dulling more and more and you end up with a glazed surface.

A Soft Ark is a different animal altogether. These stones are less dense than the aforementioned stones, and when the surface dulls, if a little more pressure is used they will shed dull grit and have new sharp grit ready to cut. If you really want a performer find yourself a Lily White Washita stone.

The reason these stones are not used so much anymore is because they aren't much good for any steel containing hard carbides like vanadium carbide or tungsten carbide. These are present in solution in a lot of the newer steel alloys. For plain carbon tool steel (straight razor, old chisels or plane blades, older kitchen knives) they are fantastic. For any modern "super" steel (SV30, HSS etc.) they are mostly useless as the carbides are harder than the silica that forms the stone.

[KL27x]

Yeah, the translucent/surgical is completely different than soft/"hard." I have nothing to complain about the translucent/surgical or the way that they're used today. IMO surgical black/translucent is a burnishing stone, and it is best at being a burnishing stone. When it gets dull and becomes like glass, peeps like that. No one thinks this is a good thing with the soft.

The reason these stones are not used so much anymore is because they aren't much good for any steel containing hard carbides like vanadium carbide or tungsten carbide. These are present in solution in a lot of the newer steel alloys. For plain carbon tool steel (straight razor, old chisels or plane blades, older kitchen knives) they are fantastic. For any modern "super" steel (SV30, HSS etc.) they are mostly useless as the carbides are harder than the silica that forms the stone.

You assume this is the case. I don't know if that's true or not, TBH. Because I don't have any "super" or crucible/powdered/sintered steels. But.

My kitchen knives are very hard stainless steel. This stainless is so hard, I initially used a belt sander to get a profile on this set of kitchen knives. Starting with 36 grit.* (Well, no, that wasn't significantly faster/better than 80; but it was taking so damn long, I tried and used 36 for the start of one knife, and that wasn't too coarse for this; more dangerous to messing up the side of the knife, though, which I did but not too bad).  I sharpen a 440C knife. I also sharpen some chrome vandium steel on it. Just a small chisel made from hardened tool steel hex bar stamped C-V? All that jazz is what you assume, or been told, or have read. But maybe 1000 people use this soft ark, and they get 1000 different results. Because of the way we share/teach/learn to use them. Seems like most people end up thinking of them as some mystical, old-timer, nostalgic thing. Which is usually called "very slow and unforgiving, but will payoff with extreme patience." This if far from the truth in my shop and kitchen.

Undoubtedly, I understand that the size of the bevel and hardness (or abrasion resistance) of the steel is definitely a limiting factor to ANY abrasive stone which cuts primarily by abrasion (not lapping/mud). Particularly on wide flat bevels, these "super steels" of high RC and abrasion resistance will make a flat stone, esp, "tap out" and skate earlier for the given bevel area in contact with the stone. This is why curving it makes it cut better.


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Imagine for just one second, a 2" wide single bevel plane blade on a perfectly flattened non-lapping stone in a sharpening guide. How much area of steel to stone do you have? It's huge! How do you expect this kind of abrasive to work like this, at all? This is like taking a file and laying it flat on your welding table, sliding it back and forth, and expecting it to cut even this soft hot rolled steel when using it in this way. This is similar to having too high a TPI for a cut. The file is harder than the steel, but the geometry doesn't work. Take a flat sanding block with some wet/dry sandpaper, and even better add some oil, and this will cut.* THIS is probably why some people claim that ark can't sharpen A2 plane blades, even. But some people can. We tend to think it's the "quality" of the individual stone. But maybe it's more likely the technique. These A2 "upsell/upgrade" blades also tend to be 50% thicker; this is 50% more bevel surface area.

If you think of the soft ark as a very fine toothed file, and you know how to use a file, you might get more out of it. Because it's excellent when used in this way. The finer the file, the smaller the area it can cut. So even after convexing it, there's a limit to what it can handle. But in this case, for most western tools anyway, it can still cut enough to be a sharpening tool, IME.

*Does this mean the file is a bad tool for hogging unhardened steel? No. It's the best unpowered tool in the world for removing material from steel chucked in a vice, when that area of removal isn't thicker than what the file will handle. Way better and faster (and more accurate and controllable) and more efficient than sand paper over a sanding block. We still use files because they are the best at what they do, not to save on sandpaper. Context matters. The sloth is way faster than the barracuda when you put them both on land.

added: Now if you rub that file on your welding table long enough, there are no shavings, still. But maybe you notice it starts to get shiny? Do you say "wow, now THIS is what the file is for! This is the best and only correct way to use a file! This is great! Files are for burnishing!"
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I might just have to buy a "super steel" to try it and report. But which "super steel?" because I don't really care to buy one let alone more.

*edited to add that I used a woodworking belt sander which is way too slow for this. I have never used a proper belt grinder, but I'm sure it would go 4-5x faster at the right surface speed for hardened steel. It's like using the wrong weight hammer for the job. The energy goes into the wrong thing. When you're too slow, here, the sandpaper takes relatively more of the wear than the metal. When you hit the right speed for this particular job, the metal comes off way faster. You will get way more sparks, too. You don't get that huge spark trail on the woodworking sander cuz it's too slow. You get hardly any at all.

[tautech]

Imagine for just one second, a 2" wide single bevel plane blade on a perfectly flattened non-lapping stone in a sharpening guide. How much area of steel to stone do you have? It's huge! How do you expect this kind of abrasive to work like this, at all? This is like taking a file and laying it flat on your welding table, sliding it back and forth, and expecting it to cut even this soft hot rolled steel when using it like a retard. THIS is why some people claim that ark can't sharpen A2 plane blades, even. But some people can. We tend to think it's the "quality" of the individual stone. I posit it's the technique. (These A2 "upsell/upgrade" blades also tend to be 50% thicker for the wow factor, even though the flex is 99% from the last tenth of in inch of from the apex; this is more bevel surface area).

That is exactly why I stopped using honing guides......say we just want to freshen the edge......which is now a 'face' of a single angle where just a shade steeper honing angle can get the dulling edge back to pristine sharpness.

The primary grind and honing angle can be restored later after a hollow grind. Halfway through a job time is money !

[CatalinaWOW]

The skills are definitely going away.  Part of the general drop in mechanical skills (at least here in the US).  80-100 years ago we were an agrarian economy.  Most people lived on a farm, and farmers have to be jacks of all trades maintaining their own gear at the end of a long slow supply chain.  Now less than 10 percent of the population is farming.  The rest work in fast food, offices, factories and the like.  Only a tiny fraction actually cut things.  And those who do use power tools and disposable tools.  The utility knife is ubiquitous in tradesmen's tool boxes.  When the blade gets dull, turn it around and use the other edge.  When that edge gets dull swap in a new one.  Or snap off the end and push the blade out a few millimeters. 

The economics of sharpening just don't make sense.  That new blade for a utility knife costs a few cents in bulk.  At tradesmen wages there is no way to sharpen a blade for that price.  Same kind of things are true at a slightly higher price point for saw blades, drill bits, router bits and the like. 

Now as a retired hobby person the economics make all the sense in the world.  As long as I don't find sharpening drudgery it makes all the sense in the world.

[KL27x]

The skills are definitely going away.  Part of the general drop in mechanical skills (at least here in the US).  80-100 years ago we were an agrarian economy.  Most people lived on a farm, and farmers have to be jacks of all trades maintaining their own gear at the end of a long slow supply chain.

I relate to these farmers. I spent most of yesterday fixing my PCB etching system. I let the mud daubers into the NPT connector for the third and final time. Luckily it wasn't a spider, this time. The mud daubers (or w/e it was) stop inside the connector, rather than messing up the inside of the regulator, like the spider. I assume there's some gross larva growing inside that hardened goo, which is probably more what stopped me from just drilling it out, rather than the prospect of cleaning the bit, after.  I got the heebee jeebees and suddenly wanted some rubber gloves just inspecting it.

I drilled out and tapped the inside of my last replacement fitting to take a 1/4" bolt as a cap.

Plugged it in, and nothing. Air lines cracked and replaced. This section of plastic air hose has to be heated and unbent so it stays straight, that there's an art to that without ruining it. This got me wondering if maybe a piece of aluminum tube stuck inside the tube would be corrosion resistance enough, but that's for another day.

(I finally noticed after a decade of doing this, that when the bubbles of my cupric tank boil over, exactly why. I just vaguely thought when the cupric turned to cuprous, the bubbles got more crazy. But it's actually when the acid runs out. )

Then I spent another 3 hours grind-turning a custom reamer for production use.

The economics of sharpening just don't make sense.  That new blade for a utility knife costs a few cents in bulk.

This exact example is actually why I started sharpening. I used to buy exacto and utility blades by the 100 pack. And once I learned to sharpen my knives properly, I swear it is faster to sharpen than it takes to get my replacement blades out and swap them out and to properly dispose of a blade (which for me this involved putting some tape over the edge, at least, before dropping it in my trash can). That little victorinox stone used to sharpen exacto knives is where it first clicked to me, that this is viable for me.

added: In hindsight, it wasn't the changing/disposing of the blades that bothered me the most. Once something becomes part of my habit, it's fine. I hated reordering them. Yes, the more you order at a time, the longer between reorder... but the more you forget how to buy more of the good quality and a decent price, and the more it matters you get the right ones. I already found a good one through trial and error and actually caring which worked the best, but that one is not available anymore. Or that seller is gone. And I don't want to investigate exacto blade brands and styles and catalog numbers, again. Because I'm not interested in that, anymore. I already figured that out... oh wait. What I figured out was a brand and a model number and a pricing/availability (and perhaps quality control) in one specific moment in time. And those things change over time (or you forget the bits of data you need to find and buy them). The rock is the same today as it was a million years ago. It will be the same a million years from now. That should cover me for the rest of my life, at least.

[tautech]

The mud daubers (or w/e it was) stopped inside the connector. I assume there's some gross larva growing inside that hardened goo.

Mason bees/wasps we call them here. They paralyse spiders with their sting and lay an egg on them and seal them in a mud cavern for their larvae to consume the meal and then emerge as new wasps to start the next generation.

Daupers have been found responsible for blocking the pitot tubes on airliners and then the fight computers and pilots get the wrong airspeed info that leads to crashes.

[SeanB]

I do tend to dress blades at work, mostly because the as bought edge is not actually sharp, so i will dress it up quickly to have a really decent cutting blade. OK I am not actually using a bought stone, just using what is to hand, either the base of a ceramic cup, or the edge of the mouse pad, a salvaged offcut of Rustenburg black granite kitchen top, which has only a top and front polish, and rough cut sides. It does make a fine mouse mat, does not move at all, very precise, and heavy enough that nobody wants to take it, plus the thickness of the thing is enough to get a disposable blade engaged enough to dry dress it. They come off a lot sharper than out of the box, and then make cutting anything so much easier.

At home I use some round aluminia hones, not actually meant to be hones, but what else do you do with a ceramic piston when somebody broke the borosilicate glass bore by careless handling. I call them my thousand Euro hones, as that is the replacement cost from Ceramus.

[eKretz]

The reason these stones are not used so much anymore is because they aren't much good for any steel containing hard carbides like vanadium carbide or tungsten carbide. These are present in solution in a lot of the newer steel alloys. For plain carbon tool steel (straight razor, old chisels or plane blades, older kitchen knives) they are fantastic. For any modern "super" steel (SV30, HSS etc.) they are mostly useless as the carbides are harder than the silica that forms the stone.

You assume this is the case. I don't know if that's true or not, TBH. Because I don't have any "super" or crucible/powdered/sintered steels. But.

My kitchen knives are very hard stainless steel. This stainless is so hard, I initially used a belt sander to get a profile on this set of kitchen knives. Starting with 36 grit. (Well, no, that wasn't significantly faster/better than 80; but it was taking so damn long, I tried and used 36 for the start of one knife, and that wasn't too coarse for this; more dangerous to messing up the side of the knife, though, which I did but not too bad).  I sharpen a 440C knife. I also sharpen some chrome vandium steel on it. Just a small chisel made from hardened tool steel hex bar stamped C-V? All that jazz is what you assume, or been told, or have read. But maybe 1000 people use this soft ark, and they get 1000 different results. Because of the way we share/teach/learn to use them. Seems like most people end up thinking of them as some mystical, old-timer, nostalgic thing. Which is usually called "very slow and unforgiving, but will payoff with extreme patience." This if far from the truth in my shop and kitchen.

Undoubtedly, I understand that the size of the bevel and hardness (or abrasion resistance) of the steel is definitely a limiting factor to ANY abrasive stone which cuts primarily by abrasion (not lapping/mud). Particularly on wide flat bevels, these "super steels" of high RC and abrasion resistance will make a flat stone, esp, "tap out" and skate earlier for the given bevel area in contact with the stone. This is why curving it makes it cut better.


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*Snipped*
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I might just have to buy a "super steel" to try it and report. But which "super steel?" because I don't really care to buy one let alone more.

No, actually, I don't assume, but apparently you do...

I have tried it. More than a few times. I probably have accumulated years if not a decade of linear honing and sharpening time. I often sharpen on something for a couple hours most every night, have done for many years since a couple decades ago when I started using straight razors, trying different stones, hones, steels and techniques. It is a relaxing hobby for me.

The "super" steels can not be efficiently cut by silica abrasive. Period, full stop. I say again, the silica is softer than the carbides contained in these steels. A knife just saying "Cr-V" on the side doesn't mean much on it's own. The vanadium needs to hit a certain percentage to make the steel difficult to sharpen. S30V is about where it starts to get pretty tough. Give it a try yourself, the steel will skate right across an Ark stone like it's on glass. Which it basically is. With a very coarse silica based stone you might get lucky and manage to cut the matrix around the carbides and pull them out allowing some small amount of work to be done but the edge will be ragged as all get out and the going will be VERY slow to say the least. These steels can not be efficiently cut with much short of diamond or CBN abrasives. Graduate to a T15 HSS blade and you won't even make much headway with an aluminum oxide or silicon carbide hone.

BTW, the file analogy sort of bears out my point. Forget the welding table, would you try using the file to sharpen the A2 plane blade? No, because it's not hard enough to cut efficiently. Same goes for the file vs. the sandpaper against the welding table. The file is nowhere near as hard as the sandpaper's abrasive, so of course the sandpaper will cut better over a large surface area... If you could apply enough pressure to the file while it was flat against the table it certainly would produce shavings. A sharp coarse double cut file probably would produce shavings quite easily. It's a matter of using the right tool for the job and the right technique for the tool at hand.

[KL27x]

would you try using the file to sharpen the A2 plane blade? No, because it's not hard enough to cut efficiently. Same goes for the file vs. the sandpaper against the welding table. The file is nowhere near as hard as the sandpaper's abrasive, so of course the sandpaper will cut better over a large surface area

eKretz. I'm treading into dangerous water here, because you're the machinist. So I look forward to your thoughts on this.

The file is supposed to be harder than the welding table, in my example. If your welding table is harder than a file, please just imagine a different welding table that isn't. In my country, hot-rolled steel has such low carbon that it can't even be heat treated to begin with. (It has to be, because it is used for structural things. And if it had too much carbon, welds would fail. I think it's spec'ed btn 0.3-0.6%, or maybe that is for common rebar? I can't recall, now). I would guess rc hardness in the 40's, scratching on the 50's at best? Furthermore, let's say the surface oxides have all been freshly ground away, so there is nothing funny on the surface.

The file will still slide over the table without cutting. It's because of the geometry. The file was optimized to make quick work of a smaller area of cut on this material. That's what the teeth were sized/shaped/spaced to do. When you try to use the entire face at the same time, it doesn't work. It's similar to having too high a TPI in a cut. You just spin your wheels, and your saw blade will just overheat and dull. No matter your feed rate/pressure, no matter your surface speed, it just won't work. Even if we give the saw infinite beam strength so we can jack the feed pressure as high as we want, well there's nowhere for the chips/swarf to go. The saw gullets will choke on the chips and rub and drag those chips against the stock. That 40 tpi saw trying to cut the 4" round, it needs to come up for air, sooner than that. It can't make that thickness of cut.**

The sandpaper doesn't cut because it's harder. It cuts because it starts out uneven to begin with, and particles break off and roll around between your sanding block and the welding table. This second bit is called lapping. And the lapping process can technically cut over an infinite surface area of cutting/contact if you are patient enough, although it will possibly have some practical limit, too. This is even better if you use some oil so you don't lose your abrasive grit.

But if you take a 1/4" thick plate of hot-rolled chucked in a vice? I'll take the good file which is optimized for fast removal at this task, over any sandpaper you want. All day, every day. The file will be faster. There's hard enough, and there's harder. OTOH, there's also geometry. Let's say the sandpaper is sharper, because we can use and throw away as much as we want. Clearances. The file has way better clearances by design. The sandpaper has just points that plow throw the material. Rake angle. File by design. Gullets i.e. swarf clearance. File by design (now that it's within its stride). The file will run circles around the sandpaper. The file is now in its element, like the barracuda in the deep sea.

Added: The soft arkansas isn't so optimal, of course. It cuts like a bad file, but that's still good enough for what we need in order to make great edges, as long as we use it within its scope or sweet spot. Although it's a bad file, it's still way better as a file than it is as a lapping stone. To lap, you need lapping paste/grit. Finally, even a bad file can potentially still cut faster than lapping, as long as we stick to the right cuts. This is because lapping is inefficient. For the amount of work input, not a lot happens, compared to direct abrasion/filing. A more accurate way to state that in a physical sense might be to say: for the amount of work, a lot more "other things" happen aside from material removal, compared to direct abrasion/filing. OTOH, the lapping stone can be firm (releasing some grit but still pretty stingy) enough to have some of the best of both actions, and the benefit of staying a bit sharper via faster turnover/renewal rate, but a bit less stable/accurate. And this balance can be good effective. These kinds of synthetic stones in their strides are probably the best for a practical balance between speed and work and accuracy, when they are tuned right for your needs.

As for the other stuff, I know the ark stone will not be able to work on any steel; and there will be a practical limit. I think curving the stone will increase this band. So now, what kind of edge bevels are we now able to do with these other materials. I think the hardness of the steel is a major factor, itself. I have a chisel made from a file. That file has the original temper. I do not sharpen it on the ark. I don't know if it would work, but it surely won't work well. I can tell by the way it feels, that it is struggling with even a fairly narrow edge bevel. (It was very slow to grind that bevel in on an aluminum oxide belt sander, too.)

I still don't know for myself that it can't be effective on "super steels," though. I have no doubt that anything with a very high hardness is not going to fare well. I know some things you said might be super high rc, but maybe others are "super steels" for other reasons? So if you suggest SV30? I might give that a shot. I wouldn't be too sure that these carbides will make that much difference aside from the total percentage increase, I think. The chromium and chromium carbides is a big part of what makes stainless so slow to grind, because that's 13% of the steel. It's a lot. The other stuff is just couple more slightly harder peanuts added to the whole can of chunky peanut butter. Maybe?


So I honestly edited the post you are responding to BEFORE I read the above post of yours just now. Just wanted you to read it,  and for other people to know what I added, and that nothing was changed to purposely shade your latest post. I hadn't even read it, yet. So this makes your post look weird, and it makes me look triply redundant, now, but I don't know better to to fix it.

added 2:18:I had also softened some of my language which might have initially been more provocative. I am not looking for any kind of trouble. This asterisked section has, in my own hindsight, become somewhat of a distillation of many of my ideas, and I was trying to flesh it out, a bit. And to streamline it. And to make it more accessible and as not-confrontational as I could, while keeping to my train of thought. This is why I had edited it, in the first place, just for whoever few people might read it for the first time (or again). I didn't know this would have happened.

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Imagine for just one second, a 2" wide single bevel plane blade on a perfectly flattened non-lapping stone in a sharpening guide. How much area of steel to stone do you have? It's huge! How do you expect this kind of abrasive to work like this, at all? This is like taking a file and laying it flat on your welding table, sliding it back and forth, and expecting it to cut even this soft hot rolled steel when using it in this way. This is similar to having too high a TPI for a cut. The file is harder than the steel, but the geometry doesn't work. Take a flat sanding block with some wet/dry sandpaper, and even better add some oil, and this will cut.* THIS is probably why some people claim that ark can't sharpen A2 plane blades, even. But some people can. We tend to think it's the "quality" of the individual stone. But maybe it's more likely the technique. These A2 "upsell/upgrade" blades also tend to be 50% thicker; this is 50% more bevel surface area.

If you think of the soft ark as a very fine toothed file, and you know how to use a file, you might get more out of it. Because it's excellent when used in this way. The finer the file, the smaller the area it can cut. So even after convexing it, there's a limit to what it can handle. But in this case, for most western tools anyway, it can still cut enough to be a sharpening tool, IME.

*Does this mean the file is a bad tool for hogging unhardened steel? No. It's the best unpowered tool in the world for removing material from steel chucked in a vice, when that area of removal isn't thicker than what the file will handle. Way better and faster (and more accurate and controllable) and more efficient than sand paper over a sanding block. We still use files because they are the best at what they do, not to save on sandpaper. Context matters. The sloth is way faster than the barracuda when you put them both on land.

added: Now if you rub that file on your welding table long enough, there are no shavings, still. But maybe you notice it starts to get shiny? Do you say "wow, now THIS is what the file is for! This is the best and only correct way to use a file! This is great! Files are for burnishing!"
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edited:
Regarding the supersteel/SV30?

So ideally, I would want to try a steel which is chock full of these vitamins C and V and w/e other chunks you like in there, but which is not going to be heat-treated as hard a file?  I'm thinking 63-65 tops? But the lower, the better.*

Ours is a completely different appreciation of sharpening, BTW. I want the process to be sweet, but also short. All jokes aside.

So I'm looking forwards to the critique from a machinist. If I got something wrong here, I will grateful to know where I've tripped up.

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*Looking at the price of these things, my enthusiasm for this experiment has wained just a little. So if you can suggest the exact brand and model you have the experience and hopefully still have, so i can have the same apple as your apple, that would be nice. And now I see it is S30V, not SV30. Oops.

** edit: Imagine if you had to cut this 4" round of mild steel using only your horizontal saw and you have only an endless and free stack of these 40 tpi blades. But the world depends on this. So you would eventually cut through this steel with this saw. And the way you'd do it is to stop and rotate this round in the vice every several seconds, at first, to target the next high spot where you can get your foot in the door, again. You would be cutting small sections of chords approximating a radius or a curve. Just nibbling off the high spots as you go off that wheel of cheese. At first this will be really slow going. But as you get closer to the center, and that radius decreases, you can cut longer between adjustments. (Because the polygon's # sides of fixed chord length, the length where the saw stalls, is decreasing; the angles of the polygon are decreasing, and the rate at which the cut thickness increases with the depth will decrease.) But I digress. When sharpening, we can't curve some of our edges away from the stone by nibbling it into a radius, because some of these edges need to be straight. We con convex the bevels in order to reduce the cutting area. Compound bevels, same idea. But there a major multiplication of surface area to stone when we put any straight blade onto the flat stone. So we can curve the stone away from the bevel.

To most people of our era, that would sound stupid. If you leave it flat, the stone will just burnish more and "act like a finer grit," right? But it's a fundamentally different tool. You can't put on or even maintain a good edge when you're burnishing too much. Even if you do it longer, you will make an apex, but that edge will not be as hard; this is where you can cut some of that schmoo off with a microbevel, and hope to get to the crunchy center. But if you want to learn it, you can get a better edge than that off the soft, directly, and to sharpen very quickly. Not just finish. Or course if you want the burnishing at the end, you would go to a different stone for that.

[coppercone2]

i dont want to think about mechanical things for a long while but restoring blades and drill bits makes sense because its basically factory new and the restored system is not working in a degraded state.

shipping materials are already a big enough disposal fee from dealing with cardboard so it makes sense, fuck thinking about how much it will cost you to cut a box open or put a hole in something, thats always better free. its a stupid ass microtax, i swear i hallucinate little parking meters on boxes

with knives the only problem is that you need a spare in rotation so you don't cut yourself when you are excited and need it to open something or prepare food etc, so it can be sharpened at the right time

i swear it makes the price of a pizza pie double because you need to deal with the stupid box and stupid pizza box related problems (its a pest shelter so it must be destroyed). I kind of wonder if you can roll up a pizza box  ,but then it starts costing you duct tape. it might as well be a truck suspension

[KL27x]

Bout time you dropped by, Copper! What are you on vacation?

Good to see ya.

[coppercone2]

Bout time you dropped by, Copper! What are you on vacation?

Good to see ya.

massive clean up and accumulated broken shit repair

[coppercone2]

awg2020, rackmount telemetry set, solar system, battery gadgets, old pc, sorting 8 shoe boxes worth of fasteners, researching crimps/tools, cable management, etc.

[KL27x]

Tending the ranch, jah. Nuther day, another sorrow.

But about these fancy rocks sharpeners, I'm still on a roll, here. Gotta excorcise these demons.

Warning: for the crazy knife people, only:
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BURR REMOVAL.
The curved stone also seems to aids with peeling off the burr. The first time this really hit home, I remember quite well. But the story starts earlier.

The experiments started small. The little Victorinox soft was probably the first. It's barely more than 1.5" long. And shortly after making it, I had the habit of sometimes carrying it around in my pocket. Mostly just to remind myself that it was there. But I had an occasion to sharpen a friend's chef knife with it.

Some days after this, I noticed the grooves I had made in the stone. This was a 7 or 8" chef knife which had never been sharpened before, so it took a little while to do, standing by the sink, using a drop of dish soap and water. This might have been the first opportunity to sharpen a factory edge in my convex stone education, aside from the tiny blade on a multitool. So this was a bit of an opportunity for me. 

The bevel has the vertical striations left by a grinding wheel. Very slightly hollowed. This gave me a good target. I found the stroke where those lines started to recede a little from both the back of the bevel and the edge end of the bevel. After some trial and error, I fell into using two or 3 long drawstrokes to cover the entire length of the edge. As you can imagine, breaking an 8" edge into two or 3 pieces on a stone that is 1.5" is way over-square. I was sawing side-to-side more than forward. So this is what must have left the grooves on the stone, in hindsight. I managed to put a respectable, clean edge on the knife, though, in my own memory. I was happy with it.

Anyhow, after seeing this, that idea to discover a better way to sharpen a longer knife on this stone got planted. What I had been doing to date was just the debur motion I used on the chef knife in my video. That had been almost immediately the first thing I fell into for sharpening, and I still use it for touchups and deburring. So I put on my thinking hat and came up with... circles. I never liked them. I still don't. I never used them. But that was the best idea I had come up with, and life went on.

It was probably a year later when I randomly clicked into doing that rowing motion figure 8 when sharpening my kicthen knives, on that 6" stone I use there. And eventually I got around to remembering to try this technique on the pocket stone.

I finally have the pocket stone and an 7" Santoku in the same room together. I got the rowing thing going on that little 1.5" stone, working my way up the blade on the one side. Then working my way back down the blade on the other side. It doesn't take very long for this to feel "right." And then I check the blade. I can feel pretty well when I have a razor edge, and this feels like a razor edge. But there's no bur. I do this another time, working my way up and then down. Still nothing. I try a third time, raising my angle just a hair, working my way up one side and down the other. Still nothing. I'm dumfounded, because I can feel I'm on the edge. I can feel the metal grinding off, and it's coarse but consistent; it's not a finishing stone, anymore, this way. And yet the edge has no fuzz. Then I finally look on the stone under a mag lamp, and there's these little balls of rolled up burr on the stone. It wouldn't have even occurred to me that I was capable of doing that, let alone on accident. I was peeling off that burr automatically while adapting this technique to this tiny stone for the first time and get getting used to the feeling.

As seen in my video, I don't do anything special to debur a knife with this method. Just by finishing with single alternating strokes, you get clean edge with no microbeveling. I felt like this was the case, before. And I feel like the edge is consistently hard and durable this way. But I was never 100% sure if I wasn't just subconsciously raising my angle during deburring or not. This day convinced me I probably am not suffering confirmation bias. I just happened to hit the right pressure and to switch sides frequently enough when using this pocket stone that the burr was coming off as I wet. This also confirms this motion works for me pretty darn well.

Also notice that it took me over a year to learn this motion, spontaneously. I hope this saves a step in someone else's timeline. But, OTOH, the time you took to read this far, you will never get back.
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[eKretz]

Ok. First of all, there are a lot of inaccuracies in the way you think you understand things working. The very first one I'm going to bring up is the hardness of the welding table. All welding tables are pretty soft. Most good ones that aren't homemade are actually cast iron. This because it's very stable and far less prone to warpage over time. One drawback is that you can't easily tack weld to a cast iron table. One plus is that you don't often need to anyway because they have holes for pushing pulling and clamping. This does take longer than a tack though.

Next, the carbon percentage of "low-carbon" steels. These are generally accepted to be equal to or below 0.2% carbon content. So 1020 steel or below. They are effectively impossible to harden by heating and quenching unless they are case hardened. The average Rc hardness of steels in this category is probably closer to 10Rc.

Next, the file not cutting over wide surface area comment. You compared this lack of cutting to the reason a fine-toothed saw blade won't cut once the chip clearance or "gullet" is clogged. Bad comparison. A file won't cut much at all in this situation because of the large amount of surface area in contact at once. For the file to cut you would need to apply a very large amount of force, but it would still cut at that point - until the chip clearance was taken up. A file's hardness is probably going to be in the mid to high 60's Rc. So only a very little harder than a good hard average knife blade. There are myriad differences between a file and sandpaper. A file also has a MUCH coarser set of teeth in most any case. So of course it will cut very rapidly in instances where surface area in contact is small. The harder the abrasive or cutting material, the less pressure it will take to cut for equal surface area in contact.

I'm going to stop there for now. In future it would help if you constrained the length of your posts a bit. There is a lot to go through there. I have other things to do, lol.

[eKretz]

Just wanted to add also that if I had to cut through a 4" round with a 40 tooth blade I would definitely not do as you described, haha. I would simply remove teeth until only every other or every third were left. Then grind the gullets deeper.

Regarding the convex stone removing burr/wire edge easier, this is because it is in contact with a low surface area and can CUT aggressively rather than rub or cut very little. Burr formation increases massively with pressure and the freer the cutting action the less burr is formed. The apex of a blade is on the order of tenths of a micron in width, so extremely flexible. If the cutting action isn't very free it will partially flex out of the way rather than cutting. Then you get a burr.

The same can be done with a curved knife edge and a flat stone. If you have a straight edged blade then the convex stone will be of benefit in reducing burr formation but it will be difficult to keep the blade edge straight. A better approach might be to sharpen the blade with a flat hone and then do only burr removal with the convex hone.

[KL27x]

I would simply remove teeth until only every other or every third were left. Then grind the gullets deeper.

I've done that, too, eKretz. But on a wood saw. So oddly, it is funny how I almost corrected you. For a wood saw, you have to leave every fourth tooth. But yeah, every third on the metal cutter.

I'm too tired and way too busy to read the rest of your post, closely, my friend. The reason I posted this here, rather than in some kind of tool or knife related forum is because I know I'm going get stabbed by a lot of pitch forks. Over here, well, there's just the one still poking, and I'll get 'round to reading your latest issues later in the day.

Thanks, in advance, and as always, for the friendly battle cry. See you on the field, soon. 

[KL27x]

Ok eKretz, I sat down and read your posts. And...

You know a lot more than me about rockwell scale hardness of stuff. I was just pulling numbers out my ass, to draw a picture. I stand corrected. I had no idea mild steel was in the 10's rc. Thanks. 

As for the rest, I gotta say. What happened? You're talking sense, now. Oddly, I haven't budged an inch, and you corrected me on everything, and yet we're in agreement. I agree with your last two posts, almost with everything. 

One thing I would nitpick about harder abrasive cutting with less pressure. I choose to think that the sharper and/or better geometry will cut with less pressure. E.g., tungsten carbide is harder than steel. But when we cut mild steel with carbide inserts, we have to take deeper cuts with a higher feedrate/pressure. This is because HSS inserts will take a finer and sharper edge. The carbide hogs off material faster, mainly due to tolerating higher temperatures, unless I am mistaken. So with the tungsten carbide, we can take deeper cuts at a time at higher tool temps.

But let's get back. Now that you corrected me and I see the light, let's examine what we now agree on. By reducing the surface area of contact, we increase the cutting aggression and reduce the rubbing and friction. I agree. I inadvertently suggested that this increased the cutting to burnishing ratio. That is clearly not correct when we put that side by side to what you said. We go with your expertise. We increased the cutting aggression: rubbing/friction ratio. Much better, right? And thanks for making this so much clearer.

That said, did you ever try anything like what I am doing? When you spent those years and several hours a week sharpening fancy stuff?

All I'm wondering is... how did you use your stone? Did you buy a barracuda and then do like everyone else? Drag it around the dog park on a leash? Did you quickly determine that like everyone else currently says, that this barracuda dog sucks at running, jumping, and fetching, but what it really shines at is playing dead?

I suspect that if you had considered all of these factors when you were using this stone, you might have tried some different things.

If you understand what parameters and what feel and feedback you should be considering to get this tool to "chooch" at its best, in its stride, to do what it's good at... if you could find a way to let the tool do the cutting and not try to make it bark like the other dogs, then you might have gotten some different results. If you have one of these funny, scaly dogs, and you're not satisfied with his ability to catch a frisbee, maybe you could try signing him up for the swim team. He might surprise you.

I'm still open to buying this fancy knife and trying it. And you don't have to answer. But in case you care... what about the Buck Vantage Pro S30V with the "Paul Bos heat treat?" This is running close to a hundo. But the spyercos are twice as much. So I hope you got nothing bad to say about this Buck or this heat treat. Even better if you can share a model you like. Heck, pretend you're buying a new knife. If you would like, I'll even send it to you when I'm done. I like to test it for at least several weeks, though. $100 soft cap? Maybe more if you twist my arm for something that strikes your fancy. That will be my payment to you. Because I'm not a knife guy. I'm in it for the process and the capabilities. And I have knives covered, already.

[KL27x]

I just remembered. I have a knife guy in my circle. So can reach out and see if he can be persuaded to buy a new knife with my wallet.

My eyes are glazing over just thinking about shopping a knife.

I'll hold off for tonight though. So if you want to be part of my experiment, speak now or it might be too late.

[eKretz]

Ok eKretz, I sat down and read your posts. And...

You know a lot more than me about rockwell scale hardness of stuff. I was just pulling numbers out my ass, to draw a picture. I stand corrected. I had no idea mild steel was in the 10's rc. Thanks. 

As for the rest, I gotta say. What happened? You're talking sense, now. Oddly, I haven't budged an inch, and you corrected me on everything, and yet we're in agreement. I agree with your last two posts, almost with everything. 

One thing I would nitpick about harder abrasive cutting with less pressure. I choose to think that the sharper and/or better geometry will cut with less pressure. E.g., tungsten carbide is harder than steel. But when we cut mild steel with carbide inserts, we have to take deeper cuts with a higher feedrate/pressure. This is because HSS inserts will take a finer and sharper edge. The carbide hogs off material faster, mainly due to tolerating higher temperatures, unless I am mistaken. So with the tungsten carbide, we can take deeper cuts at a time at higher tool temps.

But let's get back. Now that you corrected me and I see the light, let's examine what we now agree on. By reducing the surface area of contact, we increase the cutting aggression and reduce the rubbing and friction. I agree. I inadvertently suggested that this increased the cutting to burnishing ratio. That is clearly not correct when we put that side by side to what you said. We go with your expertise. We increased the cutting aggression: rubbing/friction ratio. Much better, right? And thanks for making this so much clearer.

That said, did you ever try anything like what I am doing? When you spent those years and several hours a week sharpening fancy stuff?

All I'm wondering is... how did you use your stone? Did you buy a barracuda and then do like everyone else? Drag it around the dog park on a leash? Did you quickly determine that like everyone else currently says, that this barracuda dog sucks at running, jumping, and fetching, but what it really shines at is playing dead?

I suspect that if you had considered all of these factors when you were using this stone, you might have tried some different things.

If you understand what parameters and what feel and feedback you should be considering to get this tool to "chooch" at its best, in its stride, to do what it's good at... if you could find a way to let the tool do the cutting and not try to make it bark like the other dogs, then you might have gotten some different results. If you have one of these funny, scaly dogs, and you're not satisfied with his ability to catch a frisbee, maybe you could try signing him up for the swim team. He might surprise you.

I'm still open to buying this fancy knife and trying it. And you don't have to answer. But in case you care... what about the Buck Vantage Pro S30V with the "Paul Bos heat treat?" This is running close to a hundo. But the spyercos are twice as much. So I hope you got nothing bad to say about this Buck or this heat treat. Even better if you can share a model you like. Heck, pretend you're buying a new knife. If you would like, I'll even send it to you when I'm done. I like to test it for at least several weeks, though. $100 soft cap? Maybe more if you twist my arm for something that strikes your fancy. That will be my payment to you. Because I'm not a knife guy. I'm in it for the process and the capabilities. And I have knives covered, already.

Right, better geometry does result in a freer cutting action also. My point was that for equal geometries, the harder material will cut freer. Again, many variables here.

Tungsten carbide cuts much faster than steel cutting tools due to its ability to withstand high heat but also because it is much harder. Mid-70's Rc and higher depending on the sinter mix. Also the modern coatings are even harder and have more lubricity. HSS will not take a finer edge than the right grade of tungsten carbide - the caveat is that the tungsten carbide is much more brittle. Unless it's only used for very light cuts or in a softer material like aluminum it will crumble at the edge. For a very fine finish cut of very shallow depth it can be sharpened to a razor edge. Edge prep on general-use tungsten carbide is normally a very fine radius or chamfer - or both. Sometimes what is called a T-land, which is basically a very narrow 15° or thereabouts negative edge.

Yes, increasing the cutting action is always a net positive unless you just want something to be shiny. I'm not sure what you're asking when you ask whether I have tried anything like what you're trying. I probably have though. I must have a couple hundred sharpening stones of all varieties, natural and synthetic, of all shapes and sizes. My general thoughts on sharpening are that what works for one purpose may not work for another. There is no one size fits all solution if looking for the optimal result. The process - and the tool as well if necessary - must be tailored to fit the task at hand. I've used Arks prepped anywhere from a 36 grit loose grit lapped surface to one that will reflect like a mirror. This is possible on very hard and tightly bound stones. Not so much with a synthetic hone that's designed to drop grit at the first sign of dulling.

Buck's S30V has a very good reputation; from what I understand due at least in part to excellent heat treat protocol. If you really want a holy crap tough to sharpen steel - S30V is sort of middling difficult - try S90V, M390, ZDP-189, or something along those lines. S30V is just where it starts getting noticeably more difficult. It goes up from there. Along with the price. For a truly difficult to sharpen blade of S90V or similar you're probably going to be looking at $200 minimum. And really the hard part is removing bulk material to get the blade profiled the way you want it. Putting the finishing touches on at the end is the easy bit.

Personally I prefer a full flat ground knife that is very thin behind the bevel. Most of my kitchen and pocket knives no longer have their original primary grinds - I prefer something flat ground to more like .010" behind the bevel. This not only lets them cut very freely but makes touch up sharpening take about a minute.

T-15 HSS I have intimate personal experience with, as I made a razor out of it as an experiment after some guys were wondering if it could be done at one of the razor forums. It was crudely done one afternoon in my garage mostly freehand grinding with a bench grinder, but all the same. It is VERY difficult to cut. The bench grinder had a tough time.

I've been through a lot of knives over the years. Many have been sold, traded or given away. Spyderco has good steel and heat treat. Some of their "Mule" test blades have been outstanding and very high hardness. Benchmade is pretty decent but doesn't range quite as hard in my experience. A "super" steel with a high hardness is a tough S.O.B. to abrade.

[KL27x]

Interesting.

I'm not sure what you're asking when you ask whether I have tried anything like what you're trying. I probably have though.

Specifically, I was wondering if you have tried to increase the cutting aggression and reduce the rubbing and friction of the soft arkansas stone you used when you tried several times to sharpen supers steels, such as the S30V which you assured would skate right over like glass and that novaculite won't cut these steels full stop period?

Or did you use a machinist square-verified flat piece of ark on it when it skated like glass?

And I'm curious, because I got all kinds of blades to skate over arkansas stone like glass when I tried to follow the most common advice, and I have never had any of this super steel, yet. So I'm just curious, now. What is the myth or the fact or the stone or the technique.

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Hence why I said you assume or read or think this is not possible. Even if you have tried it, you may not know. Without applying what you know (and in this case you seem bent on saying what this entire thread is about is impractical, even though you haven't tried it), maybe you were using the stone "correctly" at that time. The correct way to use the stone, which is embedded in ages old internet culture going back and entire 30 years, is to make it the slickest block of glass you can and then to spend hours rubbing a straight razor you sharpened on an 8k waterstone to get that extra special something something on it which you can't describe but you will know when you feel it.

Considering the stone has been used for many thousands of years, and during 99% of that many thousands of years, it was among the most prized of sharpening tools, I kinda doubt what you think is practical is actually the case if you asked throughout most of our human history.

I respect this culture. These guys have a right to their belief system and hierarchy of knife steels and their own holy scriptures. I'm not going to go poke their nest or challenge their bullshit. But don't bring that stuff here to wave your dick. That you've BTDT and are a card carrying member of a cult which is obviously based on capitalism and trademarks than practical use and knowledge.

After the 29 seconds of internet shopping, I already know what the deal is. When a special steel is only available in "high quality knives" for 200+ dollars, it's not a practical application of that material, but a trademark and an upsell. Somehow I never found the application where I am looking for a knife that is harder than w/e the heck mystery steel is in my knives. So using "modern knife steel" as a reason to ignore the whole point of this thread as impractical is a joke to begin with. Wait. Calling it "modern knife steel" is a joke to begin with. Modern knife steel is the same as it was 100 years ago. This other stuff is modern punch and die steel sold in knife shape to collectors.

You can't even call it the modern knife steel if 0.01% of knife work is done with it. If it was "modern knife steel" it would also be sold in a basic shape on a basic stick handle for the guy that does that job where it is so superior.

[eKretz]

Now hold on, you seem to be reading different things than what I wrote. I said the Arks (or any silica based abrasive stone) won't cut the carbides full stop, period. They will cut the steel at the coarse end of the spectrum (Washita, Soft Ark), but extremely inefficiently. And they do it by cutting the matrix around the carbides and dragging them out whole, sort of like yanking the gravel aggregate out of concrete.

And yes as I mentioned I have tried Arks and many other stones on the "super" steels very often - with a very coarse and free cutting surface. They still will not cut the carbides. They will remove steel, albeit very slowly and dragging out the carbides by digging around them. They also give up quite a lot of abrasive during the process, which they really don't do with plain carbon steels.

The only reason to use a super smoothed stone surface is for something like shaving, where feel on the face is important. An extremely fine edge with as little tooth as possible is the goal. This is the kind of edge you want for a "push" cut with no lateral sliding (or sawing, if you will) motion involved. For a sawing type cut you want some tooth to remain and a coarser finish works better, as well as keeps cutting longer.

[KL27x]

I'm sorry for my irritation to spill.

You can take over this thread with your own special interest. I'm not interested in boutique knife steel circle jerk. I've read everything you said, like you're repeating it straight from this circlejerk.

Apologies.  I think I'm done. I'm way better with people before I open my mouth.