Convex club.

[kohalajohn]

Very excited. Just arrived today. Been researching this and talking with Jarrod about this, for months now.

You can see a bit of light at each outside end, which proves the convexity.

The light, mottled side is the soft bevel setter. (although at 2.5, the "soft" is super dense).

The black translucent is the finisher.

Both sides convexed by Jarrod on his concave granite plate. Check out videos at TSS.

Honing oil is water mixed with Ballistol.

Now let the conversations begin about this new system.

The idea is that since the convexity makes it fast, you can go from bevel setter all the way to the end, just by using the finisher.

I will report back.

 

[kohalajohn]

Oh, and the photos in the background are of The Donald, who you have seen before using my simpsons brushes on his baby sum smooth face.


im

 

[stone and strop]

How does the convexity have anything to do with the speed of cutting?
It seems it would be most useful for non straight edges.
Quite a price I might add!
A one stone hone? Let us know how long that takes.

 

[bluesman 7]

Can you measure the clearance at each end? I've been using .5 mm (.02")crown over an 8" hone for my math musings. From the pictures yours looks to be a bit more crowned than this.

 

[kohalajohn]

The convexity speeds up cutting because only one bit of the edge is touching the stone. So the effortis concentrated.

Yes it is spendy.

Other question about precise angles. I don’t know.

 

[David]

I wonder how these would work on knives?

 

[Dick peck]

I think it's easier to try new things early on. I think after time we get a little set in our ways. At this time I think I'm about 3 years in. Maybe only two I can't seem to pick a starting date.so I like the idea of trying the stones. If they work well for you then they are great. I know my hard black put super sharp edges of my blades. It may just be a matter of practice with your new stones. Good luck and keep us posted.

 

[stone and strop]

The convexity speeds up cutting because only one bit of the edge is touching the stone. So the effortis concentrated.

Is that same point not making contact on a flat hone?
I mean honestly, a flat hone will stay in contact with the entire edge longer than a single point riding along a convex hone.
I've looked at Jarods "reasoning" with a major point about razor mfg.'s using this type of hone.
It makes sense for them to use such a thing because they know the razor will make contact along the entire edge while being honed regardless of the geometry. This does no favors to the poor sap that gets that razor if there WAS a problem
The good news is you will always get good contact when honing, the bad news is your geometry can get messed up and you will never know it. Unless of course you put that same razor on a flat hone

Really don't see the attraction to such a thing, to each his own.
I will stick with the flat, repeatable, maintainable hones.

 

[Acmemfg]

Remember the curved TV screens that were all the rage about 4-5 years ago? I bought one. Works ok I guess. Very doubtful I would buy another...if I could even find one.

 

[eKretz]

I'm in full agreement on the sticking to flat hones. I also agree that razor manufacturers might see a lot more use out of a hone that is convexed in one axis. A hemispherical hone of even huge radius seems a little silly to me. YMMV.

Any time a razor makes point contact rather than hitting the hone all at once over a large surface area the local cutting speed will increase - that's a simple matter of increased pressure per unit of area. That will happen whether the hone is convex and the razor is flat or if the razor is smiling and the hone is flat. Where the cutting speed decreases is when the razor has a very straight edge and is being honed on a very flat hone, unless increased pressure is used to compensate - but often that isn't possible with a razor since it will flex.

 

[bluesman 7]

That will happen whether the hone is convex and the razor is flat or if the razor is smiling and the hone is flat.

Bingo!!!

 

[stone and strop]

I'm in full agreement on the sticking to flat hones. I also agree that razor manufacturers might see a lot more use out of a hone that is convexed in one axis. A hemispherical hone of even huge radius seems a little silly to me. YMMV.

Any time a razor makes point contact rather than hitting the hone all at once over a large surface area the local cutting speed will increase - that's a simple matter of increased pressure per unit of area. That will happen whether the hone is convex and the razor is flat or if the razor is smiling and the hone is flat. Where the cutting speed decreases is when the razor has a very straight edge and is being honed on a very flat hone, unless increased pressure is used to compensate - but often that isn't possible with a razor since it will flex.

I understand the pressure increases at that area but it is also NOT in contact for very long at all (a small fraction of the time)compared to a flat hone (given a straight edge) so I would bet the "speed" is about the same.
With the reasoning proposed then shouldn't we all be honing on 1" wide hones? Wouldn't it be "faster"? I don't think so.
Even if this is not the case - for reasons I cannot comprehend, how much "faster" could it possibly be?
Would it be worth the effort to do so?
The ONLY benefit to such a creation is for productivity, nothing else. Time is money. This is why razor factory's used it.

 

[eKretz]

I don't think it is worth the effort either. However, I am all for anyone who wants to try it out trying it out, if that is what they wish to do. The speed increase on a very slow hone would probably be significant, but for myself - as I've mentioned before - I'd just rather create a small smile on any blade that didn't already have one.

One easy way to get an idea of the possible speed increase - take a file and a piece of steel, and make a cut with the file held in flat contact with the steel. Now turn the file so it's only cutting with a tiny bit of the corner and cut again with the same pressure. Observe how very much deeper the corner cut. The higher psi will definitely remove material considerably faster.

With the type of stroke necessary on a razor with this setup (rolling x basically) the material would be removed all along the edge quite quickly. To equal the material removal speed of the corner, the broad part of a file (same with flat razor and flat hone) would have to be used with much higher pressure.

 

[buca3152]

I guess a cylinder hone is next. Like the ceramic rods used for knives. I like flat stones. But am thinking there are so many ways so go for it.

 

[Chan Eil Whiskers]

I too have purchased this stone, but it's in transit. For me, this is an experiment. I know very little about the stone or what it actually does from an engineering or honemeister's point of view.

Maybe purchase is the wrong term. I might be renting it. My guess is the smaller and much cheaper version of this stone has sufficient real estate but the larger one will sell out (Jarrod's not making any more of the large 8x3 stones because they're so labor intensive to shape). I think maybe the large stone will be easy to sell should I decide to switch to the smaller stone or abandon convexity.

Looks fun?

Most of you are ahead of me in your understanding of convexity vs flatness. I don't understand any part of what this stone is about except that Jarrod says it works great. I've read all of his stuff at least a couple of times and watched his videos but it makes no sense to me, mostly.

What does make sense is the fact that convexity of the stone exposes only one little part of the edge to the stone and thus focuses the effort + speeds up the process + it should be much easier to hone an imperfectly flat blade.

Exactly why you can't go from a convex stone to a flat stone is beyond me, too, which probably well illustrates the extent of my ignorance. I don't know how to use the stone at all, not even how to start with it. Doesn't mean I can't figure it out enough to dive in.

I'm looking for information as are we all. The comments with these videos are helpful to me.

Jarrod mentions various lubricants and advises against using just plain water (too slow). I have two Arks (Norton Translucent and Hard Black) and have already discovered the benefits of synthetic oils. I've ordered the particular synthetic oil Jarrod links to + I have Ballistol if decide to go that route.

So, mostly I have a stone I don't really need in transit, a bunch of questions, and an adventure in store. Also, a firm and growing understanding of exactly how nice a padded room can be.

Great hobby, ain't it!

Happy shaves,

Jim

 

[Chan Eil Whiskers]

 

[Chan Eil Whiskers]

It would be helpful at least to me to know exactly what strokes should/do work on the convexed stones. Jarrod mentions several (normal x-stroke, rolling x-stroke, or elliptical stroke) as appropriate for the convexed stones.

You must use a normal x-stroke, ‘rolling’ x-stroke, or elliptical stroke on a convex stone.

What exactly is an elliptical stroke? It's not that I'm entirely ignorant of the terms or the strokes but that doesn't mean I have an exact understanding of the strokes, particularly that one. From watching the videos of Jarrod and the woman (at Devo?) honing it doesn't look to me like they're doing anything different from what we all do all the time, but I could be missing something, and that something could be vital.

Regular X Stroke (above)

45 Degree X Stroke (above)

Rolling X Stroke (above)

I would assume you wouldn't use the 45 Degree X Stroke but the others are okay, right?

What's an elliptical stroke look like?

I also wonder whether one can use an edge leading/spine leading/edge leading/spine leading, etc back and forth stroke (without removing the blade from the stone) on the convex stones? I'm pretty sure a half stroke is what the woman in the video posted above is doing on the convexed coticule, but she's moving almost too fast to see (yet I think I can see her flipping the blade and it's not after every stroke, right?).

[There's also some discussion as to whether her stone in the video is a coticule or a synthetic. It's a video Jarrod made before he had any convex stones. Early in his journey.]

Elliptical stroke? Here's one gentleman's description of what he calls an elliptical stroke, but is his description of something idiosyncratic or universal? This is quoted from a source which I'm not sure it's okay to quote (the rules are very unclear to me). I'll put the link and assume it can be removed if necessary. Link.

I place the blade on the hone performing circular ,I would say elliptical moves clockwise through the hone length pushing the slurry from the left side to right side keeping always the edge front, moving the blades in same time from heel to the point (estimate 20 elliptical moves).

So perhaps the elliptical is a stroke somewhat like this gentleman's using on the coticule?

What he's doing is more obvious when he flips the razor blade (at least to me it is).

I hope my questions and concerns are relevant to others exploring this topic and this stone.

Happy shaves,

Jim

 

[SliceOfLife]

I guess a cylinder hone is next. Like the ceramic rods used for knives. I like flat stones. But am thinking there are so many ways so go for it.

Bingo. What these hones and this method is doing is translating honing on a rod onto a surface that razor honers will be more familiar with. It works just fine, and is faster. But the types of stones it is effective with for razors without an insane amount of manual dexterity are limited. Honestly about the only finishing stone I’d be comfortable using this technique with is an Arkansas, or similarly hard stone with no slurrying effect.

 

[stone and strop]

One easy way to get an idea of the possible speed increase - take a file and a piece of steel, and make a cut with the file held in flat contact with the steel. Now turn the file so it's only cutting with a tiny bit of the corner and cut again with the same pressure. Observe how very much deeper the corner cut. The higher psi will definitely remove material considerably faster.

This is true given the same length of stroke but we know the contact is for much less time on any given spot.
Now take that same edge on the corner of the file but only use 1/10 of the stroke vs the full stroke on the flat side. How much variance is there now?
This is my point. Yes, it has more psi so will cut quicker in that one spot but for a much shorter period of time than full contact for a longer period.
Removal of metal on any given object is time on abrasive and pressure. Time being reduced and pressure increased - for me- is the same as longer on the abrasive with less pressure. The difference must be very, very, small.

 

[Chan Eil Whiskers]

I see that Jarrod Connerty of Superior Shave is participating in this and other similar conversations, but on his website.

Scroll down to the Q&A towards the bottom. Link.

Happy shaves,

Jim