Convex Hones

[drmoss_ca]

So, a funny story. Convex Arkansas stones are currently popular, and the guy selling them at the_superiorshave_com says they are used all the time in Germany. Apparently that is the case as a razor and hone with two single points of contact - one on the spine and one on the edge - can still be honed no matter how badly it has been ground. I understand the geometry involved, and I can see that it makes sense. I would rather a razor was properly ground, but needs must where profit is in play.

Some years ago, I won't say how many as I'm still a youngster, I bought a complete set of Naniwa Superstones from a now defunct online store. I used them, found them good and decided to make them as good as could be. Big mistake! The moment my Shapton DGLP started flattening each and every one, an elliptical flat spot started to appear in the middle, and after a good deal of work, covered much of the surface of each. At this point, being tired of lapping these hones, I tried to hone a razor. But now the hones did not work as before - not even close! So what did I do? Continue lapping them flat, keep on honing, or what? I did what anyone with more money than sense would do, and bought another complete set. The new set worked just like the first.

That was a bit of a mystery to me, until I started to read about convex Arkansas stones. The meaning of the ellipse became clear: the hones were convex along their length and across their width, and I was beginning to flatten that out. It would have been nice if the manufacturer or the seller had said something about not flattening them with a lapping plate, but they did not. That's in the past.

I have continued to use the Naniwa Superstone 1k and 3k as bevel setting hones, and I bought the 1k Chosera as a sign of faith in the future. Maybe it is convex in both directions too. I am not going to try to find out! I'll use it just as it came, and shall not flatten it at all.

 

[jaro1069]

So, a funny story. Convex Arkansas stones are currently popular, and the guy selling them at the_superiorshave_com says they are used all the time in Germany. Apparently that is the case as a razor and hone with two single points of contact - one on the spine and one on the edge - can still be honed no matter how badly it has been ground. I understand the geometry involved, and I can see that it makes sense. I would rather a razor was properly ground, but needs must where profit is in play.

Some years ago, I won't say how many as I'm still a youngster, I bought a complete set of Naniwa Superstones from a now defunct online store. I used them, found them good and decided to make them as good as could be. Big mistake! The moment my Shapton DGLP started flattening each and every one, an elliptical flat spot started to appear in the middle, and after a good deal of work, covered much of the surface of each. At this point, being tired of lapping these hones, I tried to hone a razor. But now the hones did not work as before - not even close! So what did I do? Continue lapping them flat, keep on honing, or what? I did what anyone with more money than sense would do, and bought another complete set. The new set worked just like the first.

That was a bit of a mystery to me, until I started to read about convex Arkansas stones. The meaning of the ellipse became clear: the hones were convex along their length and across their width, and I was beginning to flatten that out. It would have been nice if the manufacturer or the seller had said something about not flattening them with a lapping plate, but they did not. That's in the past.

I have continued to use the Naniwa Superstone 1k and 3k as bevel setting hones, and I bought the 1k Chosera as a sign of faith in the future. Maybe it is convex in both directions too. I am not going to try to find out! I'll use it just as it came, and shall not flatten it at all.

And i'm sure you will get to use them for many, many, many years to come.....

 

[Longhaultanker]

“...a razor and hone with two single points of contact - one on the spine and one on the edge - can still be honed no matter how badly it has been ground. I understand the geometry involved, and I can see that it makes sense.

This makes more sense to me than anything I’ve read or video I’ve watched on the whole convex issue. I’m still not a fan, but at least I understand it better.

But here’s the question I’ve got: doesn’t the rolling X stroke do the same thing?

 

[drmoss_ca]

I think it does, and the convex hones are just a way speeding up and simplifying the honing to make industrial production more efficient.

 

[Longhaultanker]

Of course, taking a notoriously slow stone , which I love, and making it faster. Speed, faster, faster. SMH!

 

[cladium]

Longhaul this was asked and answered to the other thread, still hasn't changed.

Rolling x isn't exactly the same,...yes it is the same in terms of point to point issue avoiding (truly solving) grind problems

But you're still aligning the edge via a line also touching spine.

When the hone is curved upwards down its long axis, vs just across the short axis, you are never touching the spine and edge with a line, they're instead being touched with an arc, an arc that creates a hollowed and more fragile but sharper bevel °

upward curve on stone long axis = for bevel shape advantage, upward curve on stone short axis = for speeding up due to avoiding unnecessary extra honing on warped blades

a fine honing rod equally avoids addressing warp issues, but fails in the ability to alter bevel shape

a big honing wheel with a flat edge, if its edge were as wide as razor cutting edge, would make the better bevel just like the bench stone curved upward on its long axis, if the two diameters were equal. But then when honing a warped razor you either burn off 'extra' steel fixing it OR u will not hold spine flush across the whole edge of such a wheel (aka rolling x)

 

[global_dev]

bought a complete set of Naniwa Superstones from a now defunct online store. I used them, found them good and decided to make them as good as could be. Big mistake! The moment my Shapton DGLP started flattening each and every one, an elliptical flat spot started to appear in the middle, and after a good deal of work, covered much of the surface of each.

Interesting, so you think these were intentionally convex? How would someone maintain that or a similar convexity across the set?

 

[drmoss_ca]

I have no idea - I was surprised to discover it when I tried to flatten them. To maintain convexity is fairly simple - just use your nagura or lapping plate preferentially around the edges rather than evenly, but when you don't even know the hone came convex, how would you know to do that?

 

[global_dev]

I think an interesting discussion out of this though, is if you bought only one or two of these convex hones, for your progression, would be difficult to get to the edge with a mix of the typical flat finishers? Or vice versa?

these hones needed to be an intentional convex purchase, no?

 

[drmoss_ca]

I bought a whole set, with no inkling they were anything other than flat (after all, who suspected that hones were anything other than flat?) How "typical" are your flat finishers? Are they truly flat? Have you looked?

I'm not trying to be difficult here. I did not know what I'd bought, and I bought a second entire set with which I have got along nicely without trying to flatten them. Naniwa do not sell them as convex hones as far as I know, though maybe these days they could profit from doing so. I'm just recording my experience, and you may make of it what you will.

If you would like to examine them for yourself, I'll be happy to sell both sets at half price.

 

[global_dev]

I meant “you” rhetorically, not specifically you.

i meant if someone unknowingly purchase one to plug a spot in their progression, Or added a non-convexed to a convex progression that it would be slightly problematic

i ask this because I’ve been fooling around with convexed synths and some finishers recently that are all from a concave plate i made. And without any significant experience In mixing them (hadnt felt the need to try that yet, doesn’t really make that much sense) i was curious.

 

[global_dev]

How "typical" are your flat finishers? Are they truly flat? Have you looked?

I use a flat granite piece or atoma for flatness of hones, and my straight edge rulers show they are pretty flat.

 

[drmoss_ca]

I'm sorry for being so short, I should have been kinder. Since all of them have the convexity I assume it is a feature, not a bug. It would be better if they actually said it on the box (maybe they do, but in Kanji), as it becomes apparent they will hone nicely if you use x-strokes, but not so well at all if you use straight strokes. The older set is no a hybrid of a flat ellipse in the centre and edges that fall away ever so slightly. I suppose I ought to raise the gumption to finish the job and make them entirely flat, but TBH I'm not inspired - I don't use them at the moment and if I do want to use a Superstone or someone wants a razor done on them, I can use the new set.

 

[Marshal]

How would someone maintain that or a similar convexity across the set?

Probably with the little red Naniwa rubbing brick, it's small so it can easily be manipulated to keep a curved shape across the stone. Or if they were aware of the convex shape and seeking to maintain it, lift the stone slightly while "flattening it" to take a little off either side. Of course if they've got the Naniwa flattening stone (or similar, I have a Norton one) they can put a concave shape down the center of the stone to keep a slight convex curve on their hone. Maybe by putting a piece of 300 grit sand paper on a suitably curved surface and running the flattening stone back and forth until it takes the desired shape.

I'll happily keep mine flat, as I've spent a lot of time and elbow grease making every synthetic and natural sharpening rock I have as dead flat as my hands are able. But it's an interesting idea that I can see the merit of.

 

[global_dev]

I’ve done that with the naniwa nagura, but you can tell that some of the progression stones are “conditioned” differently than others. Not a huge deal as you described ways to keep it concave, but its really soft.

 

[cladium]

Marshal if you've already flattened hard natural stones and are happy with them no sense messing about, that is hard hard work.

But if you have any finishing hones left unaddressed or any sort of soft finisher like naniwas, you really should try forming it to be like a wheel, it won't be as difficult as you think (provided stone's soft!) and you'll be shocked how different it can make the feel, as will I think anyone who never tried it. If they tried it and think it felt the same, which I do doubt, they need to reduce their hone's diameter until their hands feel it notably during honing, in which case surely any beard should feel the difference by then; it is a materially keener edge, this is just math.

I like the naniwas b/c you can hand form them relatively easily with just files and sandpaper and a chisel, mine are ~2mm crowned in the dead center vs the corners and I just filed off the four edges and then constantly blend toward that summit point until the curves are gentle/consistent to the eye test. Feels like the edge is going over a rolling speedbump or something, you can easily feel the push back to the razor shape FROM the hone and as you watch it you see about 2cm of contact and the pressure on the contact varies across the span in a way you can see. They swell and change when they dry, and I don't know if the resin base or the material causes this. But that's OK, just using a ruler and eyeballing it and the rubbing stone or a bit of sandpaper, you make simple adjustments just before you use the hone each time - remember the stone's soft, and the razor incumbent shape is being cut in to gently right upon the bevel itself where it naturally will flex, it doesn't have to be exact and it isn't like the razors' shape is 100% exact either, it is produced in a geometric range of acceptance and that range varies across the edge/spine etc. You just need a hone shape that is enough to feel shaving but never cutting too much in to chip the blade (from making the bevel too thin/fragile) or carve in to the area behind the bevel (this could be a problem for any old razor that was honed with tape in the past).

 

[A CUT ABOVE]

I just purchased a concave plate to make my stones convex. First stone I lapped was a Dota Creek polishing grey stone. I have been using a convex surgical black for a year and there is no question the edges are sharper, smoother shave and much faster to hone. I plan to convex all my stones. There are a lot of opinions about using convex stones. Proof is they have been using them for hundreds of years.

 

[cladium]

Have used for yrs only problem I see is you do consume hone quickly if it is a waterstone and it doesn't work right with taped spine so razor appearance must defer to its correct shape. Maybe end users will try them, or maybe not. They do not know what they're missing. Shame for them!

 

[kiruiz]

Convex Vrs No convex
In my opinion it’s just another way to do your hone. You like it, go for it. But it’s not the only way or the best. Japanese people never use convex for thousands of years and why?
All of the Japanese systems are meant to be flat. You choose your venum but I think it’s just another way to do it.
ken

 

[cladium]

have you been to a cutler in Japan? They have convex hones all over the place there, or did in my one trip there 20yrs ago anyway. They definitely know about using them, I walked from the main temple back to the train in Kyoto maybe 3-4 mi. on a lovely spring day and passed quite a few tiny shops in people's garages which was common there, some had western razors and quite convex hones, presumably to make the bevels concave so they would flex and be thinner which are good for shaving if not for chopping wood. Might have been more used there for scissors, but the reasons they used them didn't change - shape the stone as a wheel if you deliberately want to thin the edge for whatever reason, pretty simple.

did you see that post on another forum of that book from Norton from the 1920s or so which said a razor bevel is supposed to be concave? and did you ever use one for a rasr?