Intentionally Convex Coticule ?

[alex1921]

What was happening pre 2017/2018 when the convex hone concept was reintroduced to the American audience?
Were the Europeans casually convexing their hones and Americans were resisting? Like that TI executive story.
Were the Dovos all butchered by being honed on flat stones?

Before somebody says they all used pasted strops, I am not buying that because back when I was starting in 2017 I would go on a German and a French forum and those guys loved rocks as much as we do.

 

[H Brad Boonshaft]

I recently had this conversation with another member about this thread, relating my experience with Convex honing. I thought we could all learn something if the postulators and haters (hate the world) would stay out of it.

What is there to “get” from convex honing that we are missing, and what are we doing wrong if we are not getting more keenness or comfort from convex honing?

I’m squeezing, but I get no juice…

 

[JPO]

I honed on slightly convex hones for quite some time. Maybe 1-2mm crown, and could not tell a difference in the edges from flattened stones. In my latest experiment with the katana hone, I could not tell the difference in the compound bevel vs flat, though I suspect that the razor thickness could be the main cause of that.

Flat is easy. I deglaze my hard JNat finishers fairly often to keep them cutting, and it’s a lot easier to maintain a flat hone. Flat is a known quantity. Razor angles vary from 12-24 degrees, so assuming a benefit from a convex or concave hone without knowing what the razor is made like doesn’t make a lot of sense to me.

Mr Ryoichi and Iwasaki both say use flat stones.

View attachment 1808376

And he knows a thing or two about razors. Short version video below.

You call that a curve. This is a curve. Does it make a difference Yes. I don’t care what some old dude in Japan says

 

[JPO]

I recently had this conversation with another member about this thread, relating my experience with Convex honing. I thought we could all learn something if the postulators and haters (hate the world) would stay out of it.

What is there to “get” from convex honing that we are missing, and what are we doing wrong if we are not getting more keenness or comfort from convex honing?

I’m squeezing, but I get no juice…

I think you need to go and squeeze something else.

 

[Steve56]

I’ve read @JPO;s translation of the German paper. It appears that they are using convex hones to shape the bevel and flat hones to finish. This is rxactly what the Japanese do with those convex katana hones. They shape the ura, or concave side of a knife or sword with the curved hone, but they finish sharpen on flat stones.

I think that when the German paper was published was before ‘die hex’ or the Ern hollow grinding machine, so we might speculate that razors were thicker then (mine from that era are) and might benefit from thinning at the edge. But across a 0.5mm bevel it makes no sense to me. A katana bevel is in inches.

 

[Darth Scandalous]

I lap my synthetic stones before each use, no grid, no straight edge and quick lap/clean during use and before final laps. They were all pencil grid lapped when new, years ago.

Same, they don't really stay perfectly flat long anyway, but refreshing the surface seems to be pretty useful.

What was happening pre 2017/2018 when the convex hone concept was reintroduced to the American audience?
Were the Europeans casually convexing their hones and Americans were resisting? Like that TI executive story.
Were the Dovos all butchered by being honed on flat stones?

Before somebody says they all used pasted strops, I am not buying that because back when I was starting in 2017 I would go on a German and a French forum and those guys loved rocks as much as we do.

According to Florida Man, people were (him included) were inadvertently ruining their razors (which wouldn't shave out of the box) by resetting the bevels and honing on flat stones. In his telling, TI told him he was doing it wrong.

I recently had this conversation with another member about this thread, relating my experience with Convex honing. I thought we could all learn something if the postulators and haters (hate the world) would stay out of it.

What is there to “get” from convex honing that we are missing, and what are we doing wrong if we are not getting more keenness or comfort from convex honing?

I’m squeezing, but I get no juice…

What Florida Man preaches is that a bevel that's concaved will cut differently. It's thinner behind the edge so it's sharper from a geometric perspective. My question, is does that impact edge retention? I assume so. Maybe not enough to make a difference. But flat bevels in the 16 to 18 degree range shave me just fine, so I don't see a lot of value in thinning them out further.

 

[Darth Scandalous]

I’ve read @JPO;s translation of the German paper. It appears that they are using convex hones to shape the bevel and flat hones to finish. This is rxactly what the Japanese do with those convex katana hones. They shape the ura, or concave side of a knife or sword with the curved hone, but they finish sharpen on flat stones.

I think that when the German paper was published was before ‘die hex’ or the Ern hollow grinding machine, so we might speculate that razors were thicker then (mine from that era are) and might benefit from thinning at the edge. But across a 0.5mm bevel it makes no sense to me. A katana bevel is in inches.

Chisels, too. But like you say, it's on the macro level, not the micro level.

 

[alex1921]

I think you need to go and squeeze something else.

Not cool man.

 

[Steve56]

You call that a curve. This is a curve. Does it make a difference Yes. I don’t care what some old dude in Japan says

Wait a minute John, isn’t the assumption that old guys know better than young guys, and old dead guys know best of all?

But more seriously, my previous comment about half the people not feeling a difference in the edges is still holding up, John can feel a difference, I cannot. And that might not be entirely the result of the hone shape. Different people prefer different things, and some faces/beards might feel a difference while others do not.

 

[JPO]

Not cool man.

Well being called obsessive is not cool man either.

"I have tried Convex honing, I have the stones. I am probably more honing obsessed than the average dog in this forum, though not as much as JPO."

 

[alex1921]

Same, they don't really stay perfectly flat long anyway, but refreshing the surface seems to be pretty useful.

According to Florida Man, people were (him included) were inadvertently ruining their razors (which wouldn't shave out of the box) by resetting the bevels and honing on flat stones. In his telling, TI told him he was doing it wrong.

What Florida Man preaches is that a bevel that's concaved will cut differently. It's thinner behind the edge so it's sharper from a geometric perspective. My question, is does that impact edge retention? I assume so. Maybe not enough to make a difference. But flat bevels in the 16 to 18 degree range shave me just fine, so I don't see a lot of value in thinning them out further.

From what I read a while back when Boris from France had a post about it he mentioned that the edge retention was actually worse, the edge was chipping faster and the razor needed to be rehoned after few uses. Again, not my experiment, just sharing what a razor maker wrote.

 

[Steve56]

My question, is does that impact edge retention? I assume so.

I think that would depend on the particular razor, how thick the metal is at the shoulder of the bevel. I wouldn’t dream of putting a Filarmonica 14 on that katana stone, the TI yes, of course.

 

[Steve56]

Well being called obsessive is not cool man either.

We’re engineers John, of course we are obsessed.

 

[Darth Scandalous]

I think we're all a little obsessed, or we wouldn't be having this discussion.

 

[alex1921]

Well being called obsessive is not cool man either.

"I have tried Convex honing, I have the stones. I am probably more honing obsessed than the average dog in this forum, though not as much as JPO."

I wouldn't say honing obsessed in a honing section of the forum is a bad thing. We are all honing obsessed. Who in their right mind keeps rehoning razors to test stones over and over.

 

[Darth Scandalous]

From what I read a while back when Boris from France had a post about it he mentioned that the edge retention was actually worse, the edge was chipping faster and the razor needed to be rehoned after few uses. Again, not my experiment, just sharing what a razor maker wrote.

worse, for concaved bevels?

 

[JPO]

We’re engineers John, of course we are obsessed.

OK. But that is only OK to say if you are an engineer. We are nuts.

In my world the sum of the forces is always zero.
Marine engineers don't agree.

 

[alex1921]

worse, for concaved bevels?

Yup.

 

[ZeelandsRoem]

Were the Europeans casually convexing their hones and Americans were resisting? Like that TI executive story.

Before somebody says they all used pasted strops, I am not buying that because back when I was starting in 2017 I would go on a German and a French forum and those guys loved rocks as much as we do.

Vast majority of European users definitely do not convex their stones, at least not significantly more than the current US ones.

As for stropping on paste, this was/is common among those who do not own stones or prefer the very cheap and simple approach. If someone is more into this, then chances are he will own a few stones and using them.

In his telling, TI told him he was doing it wrong.

My last TI, which I acquired somewhere in 2023, had a flat bevel and was stropped on diamond paste. I could be wrong but maybe TI no longer uses convex hones.

 

[Darth Scandalous]

Yup.

That tracks with my assumptions, then.