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Why can't you set a bevel off a finishing stone with high pressure?

[NB - This is a *hypothetical* question. I'm not going to do this, and not asking for tips about bevel setting, or better stones to use. Or indeed for anyone to point out that sharpening a knife is different from honing a razor, without saying why... ;)]

I can form, flip and remove a burr on Aogami Super with a Charnley &c. in no time at all to put a bevel/edge on a kitchen knife. Using high pressure at first, going down to barely even touching the stone by then end. Takes a few minutes.

Aogami Super is HT-ed harder than the large majority of SRs I guess (?). I'm also having to remove a load more metal to set the bevel/edge initially because a knife is bigger and thicker. Plus I'm freehanding, and holding an angle at high pressure is going to be more difficult than doing the same on a razor.

So... Why couldn't you take a razor from bevel through to finish on a single, fine, stone starting at very high pressure and gradually decreasing the amount used?
 

rbscebu

Girls call me Makaluod
One, and not the only, problem with using high pressure on a SR is that most SR's have a hollow grind and a very thin blade (compared to must knives). High pressure tends to bend the blade and this lifts the edge off the whetstone.
 
High pressure would deflect a razor - not making contact at the edge.
For me edges are always better in a progression.
I suppose anyone could just use a finisher, although I see no need for high pressure but rather, many, many laps if you were so inclined.
Why would you be so inclined though 😏
 
You can, depending on the stone.

A 12k will easily fully set a bevel and even remove a small chip. Using pressure will raise a burr, but you can easily remove the burr completely by jointing the edge,( one or two lite strokes on the corner of the stone) and reset the bevel in 10-20 laps.

Google (12k chip removal)
 
Why in the world would you want to waste stone applying a completely ill suited tool for the job for the required amount of laps to do that? Good finishers tend to cost more than a typical bevel setter as well.
 
Under 300 laps. 80 circles, 206 laps and about 15 minutes. On a thin hollow ground Henckel, Platinum 5/8 hollow ground razor.

No stone waisted. You don’t need a lot of pressure, use circles. Most synthetic stones are more aggressive than we give them credit for.

Back in the day, folks had a course stone and a fine stone, mostly naturals and did just that for hundreds of years.
 
Thank you for thoughts here guys...

The bending or deflecting problem because of how thin/delicate a razor is hadn't crossed my mind, that would certainly be a significant issue I imagine. Especially as it would happen differentially along the length. Exactly the kind of thing I was hoping people would point out, ta!

Interestingly now that I think about it... if you did this - setting a bevel at high pressure with the razor slightly deflecting initially - apart from being a bit of a mess and uneven, you'd end up with a kind of hamaguri sharpening, with the bevel shoulder eased, and some convexity blended into the edge. I doubt there'd be much point in that on a razor, but that's what'd happen.

As I said; it is not something I want to do. I just wanted to think about why.
 
So, don’t use so much pressure. Use circles.

It has been done with slates, coticules, Jnats, Arks and other naturals that will finish for hundreds of years. A good Jnat will easily finish a bevel from 1k,even set a bevel or remove a chip with just diamond or tomo slurry.

It is nothing new, shocking or wasteful.
 
Pressure goes up pretty easy by using the off hand vs honing in hand. Even a light finger touch on the razor increases it a noticeable amount and avoids some of the problems you might get with torqueing a full hollow honing in hand. It's pretty easy to demonstrate this by putting a stone and razor on a scale and zero it out and then hone.
 
Like the guys said, for perfect edge any flex is something you strive to avoid. But yes it can be done. You can dig a 100’ well with a screw driver or fall a tree with a pocket knife if patient and persistent. But the old adage of the right tool for the right job rings to mind.

It’s not a knife. This fits into the razor nuisance and difference in honing for sure. It’s also why so many excellent old finishers have been mutilated by someone with a knife :-( So many nice hones with massive dishing in one spot…. there is no doubt how it occurred.
 
[NB - This is a *hypothetical* question. I'm not going to do this, and not asking for tips about bevel setting, or better stones to use. Or indeed for anyone to point out that sharpening a knife is different from honing a razor, without saying why... ;)]

I can form, flip and remove a burr on Aogami Super with a Charnley &c. in no time at all to put a bevel/edge on a kitchen knife. Using high pressure at first, going down to barely even touching the stone by then end. Takes a few minutes.

Aogami Super is HT-ed harder than the large majority of SRs I guess (?). I'm also having to remove a load more metal to set the bevel/edge initially because a knife is bigger and thicker. Plus I'm freehanding, and holding an angle at high pressure is going to be more difficult than doing the same on a razor.

So... Why couldn't you take a razor from bevel through to finish on a single, fine, stone starting at very high pressure and gradually decreasing the amount used?
I just did a test with a 5/8 full hollow Dovo. My Naniwa 12 k broke in half a few years ago. I convexed one side and lapped the other side flat. This razor already had an ok bevel. The edge was dragged two times over the edge of the stone before i started.
When you use convex stones you can to some degree manipulate where you working on the bevel, effectively working from the bevel shoulder to the apex. When you work on a smaller section the pressure is increased with the same pressure you use on a flat stone. I used more pressure then normal on the convex side mostly using half strokes. I then moved to the flat side and finished the edge with light strokes. This is sort of the same concept as you use with knifes. When you move to the flat side your bevel shoulder is not in contact with the stone initially. You are basically creating a micro bevel by working on a smaller part of the bevel. This cleans up the edge and refines the apex.
The process took a little longer time then a normal progression, but not much. It would probably go much faster if i had a full sized stone to.
So if you only had one finisher you could have one flat side and one covex side and get by ok for lighter bevel work.
I have also done this with coticules. I use a convex fast coticule with a little pressure and slurry, then a flat fine Les lat.
You work the bevel with pressure and refine and align the apex with light pressure.
The process probably works best with flexible grinds, but i did get a nice edge off one of my hart steel razors.

The problem i have with synthetic finishers is to read the feedback. It is easy to be fooled by how it feel on the stone. The razor starts to stick to the stone long before it is finished, because you have polished bevel planes. I always get more consistent results if i go back to a 3k or lower if i am not doing repair work.
 
[NB - This is a *hypothetical* question. I'm not going to do this, and not asking for tips about bevel setting, or better stones to use. Or indeed for anyone to point out that sharpening a knife is different from honing a razor, without saying why... ;)]

I can form, flip and remove a burr on Aogami Super with a Charnley &c. in no time at all to put a bevel/edge on a kitchen knife. Using high pressure at first, going down to barely even touching the stone by then end. Takes a few minutes.

Aogami Super is HT-ed harder than the large majority of SRs I guess (?). I'm also having to remove a load more metal to set the bevel/edge initially because a knife is bigger and thicker. Plus I'm freehanding, and holding an angle at high pressure is going to be more difficult than doing the same on a razor.

So... Why couldn't you take a razor from bevel through to finish on a single, fine, stone starting at very high pressure and gradually decreasing the amount used?
Excessive wear on the stone. Excessive flexing of the blade and resulting burr and fin edge. Pressure is good when doing edge repair, removing a lot of steel, or briefly when deliberately raising a burr for using the burr method of setting a bevel. Any other time, light to very light pressure is your friend.

A razor behaves much differently from a knife on the hone, due to the much more acute and carefully controlled bevel angle. A knife's edge is more robust and does not flex as easily. Also a knife benefits very little from application of abrasives finer than 1k or 2k, because of the usage pattern. You don't pamper a chef knife or a butcher knife. You gasp in horror when you see someone slicing paper with your favorite razor. You often strop a kitchen knife on a butcher's steel rather than honing it. You would never attack a steel bar with your razor. The razor is more delicate and more easily damaged.

When you are unsure, always follow the herd. They must have something there. Experiment, and you are probably repeating what thousands of other guys have already tried. The reason the thundering herd does not do it that way is that it could not be proven to be better than the regular old way of doing things. If you want to try setting a bevel on a finisher with heavy pressure, by all means, do so and don't let me discourage you, if you are truly on a quest here. The common way may not be the most refined or most technically advanced way, but it will work well enough to keep the herd mooing contentedly so after going rogue with your heresy, you can always just pretend it never happened and get back on one of the heavily traveled paths.

If you are getting a great edge doing what you are doing, you don't need to understand it. Just keep doing it.
 
Excessive wear on the stone. Excessive flexing of the blade and resulting burr and fin edge. Pressure is good when doing edge repair, removing a lot of steel, or briefly when deliberately raising a burr for using the burr method of setting a bevel. Any other time, light to very light pressure is your friend.

A razor behaves much differently from a knife on the hone, due to the much more acute and carefully controlled bevel angle. A knife's edge is more robust and does not flex as easily. Also a knife benefits very little from application of abrasives finer than 1k or 2k, because of the usage pattern. You don't pamper a chef knife or a butcher knife. You gasp in horror when you see someone slicing paper with your favorite razor. You often strop a kitchen knife on a butcher's steel rather than honing it. You would never attack a steel bar with your razor. The razor is more delicate and more easily damaged.

When you are unsure, always follow the herd. They must have something there. Experiment, and you are probably repeating what thousands of other guys have already tried. The reason the thundering herd does not do it that way is that it could not be proven to be better than the regular old way of doing things. If you want to try setting a bevel on a finisher with heavy pressure, by all means, do so and don't let me discourage you, if you are truly on a quest here. The common way may not be the most refined or most technically advanced way, but it will work well enough to keep the herd mooing contentedly so after going rogue with your heresy, you can always just pretend it never happened and get back on one of the heavily traveled paths.

If you are getting a great edge doing what you are doing, you don't need to understand it. Just keep doing it.

Thank you for this!

Little bit of background... the reason I was asking was specifically because I don't want to do it, but I wanted to understand that. I sharpen things every day, for a living (as well as razors for myself), and understanding the differences is important. If I can get away with understanding why not to do something, without actually having to actually do it and feck something up - that's ideal! And I do quite a lot of restoring things, so understanding how pressure affects different kinds of edges is useful.

I'd say a couple of things though... softer steel and less material removal would mean that excessive stone wear when doing something like that on a SR would be a comparatively insignificant issue for me. I get an awful lot more wear from sharpening knives, and flatten stones every day, so don't really mind that bit. Also - bevel angle on a razor is probably going to be the same or actually slightly higher than most Japanese kitchen knives get sharpened, which is about 15 degs, and often a lot less for single bevels.

I realise that none of the above was obvious in my original post, and that I'm working with slightly different types of quite high-end knife than a lot of people might. I just spend quite a lot of time thinking about this kind of thing!

---

I have a follow up question though, which I asked a while back, but didn't get a completely clear answer: how much of the blade of a (traditional western) straight razor is HT-ed?

Someone I think posted a picture showing one they'd polished to reveal a kind of hamon line, and differential HT, along the length of the spine. With the hardened steel starting kinda where the grind began. Is that the norm? It must affect honing and how evenly you remove material on the spine and edge...?
 
I have to believe the answer is sure - it should work - but as others have said, probably not optimal. Like trying to break out of jail with a nail file.
 
Thank you for this!

Little bit of background... the reason I was asking was specifically because I don't want to do it, but I wanted to understand that. I sharpen things every day, for a living (as well as razors for myself), and understanding the differences is important. If I can get away with understanding why not to do something, without actually having to actually do it and feck something up - that's ideal! And I do quite a lot of restoring things, so understanding how pressure affects different kinds of edges is useful.

I'd say a couple of things though... softer steel and less material removal would mean that excessive stone wear when doing something like that on a SR would be a comparatively insignificant issue for me. I get an awful lot more wear from sharpening knives, and flatten stones every day, so don't really mind that bit. Also - bevel angle on a razor is probably going to be the same or actually slightly higher than most Japanese kitchen knives get sharpened, which is about 15 degs, and often a lot less for single bevels.

I realise that none of the above was obvious in my original post, and that I'm working with slightly different types of quite high-end knife than a lot of people might. I just spend quite a lot of time thinking about this kind of thing!

---

I have a follow up question though, which I asked a while back, but didn't get a completely clear answer: how much of the blade of a (traditional western) straight razor is HT-ed?

Someone I think posted a picture showing one they'd polished to reveal a kind of hamon line, and differential HT, along the length of the spine. With the hardened steel starting kinda where the grind began. Is that the norm? It must affect honing and how evenly you remove material on the spine and edge...?
A 15 degree bevel angle on a razor is inclusive. From one bevel face to the other. A 15 degree bevel angle on a knife is 15 degrees between one bevel face and the center of the bevel. The central plane of the blade. So a 15 degree knife equals a 30 degree razor. Except that there aren't any.

GENERALLY the entire blade is heat treated and tempered and the only differences in hardness are due to greater mass in the spine than the main part of the blade. This difference is of little consequence in honing. NO consequence, actually. Just hone it according to the method you choose following the regimen you like and the tools called for. The spine may be slightly softer due to shorter soak time at critical heat prior to quench. It may also be slightly harder due to the tempering process having full effect on the edge and not on the spine. I am not particularly experienced, let alone expert, at making razors so someone else will possibly correct me on that. However it also presents more face to the honing media and you are torquing the edge down ever so slightly as you hone, if you know your business. And as the spine wears, magically the spine's bevel face expands, slowing the incursion by the abrasive. When the honer doesn't do dumb stuff like hone on a bench (as a beginner) or hone on the shoulder or use excessive pressure or lay a finger on the blade or struggle to "control" the razor with two big meathooks, then the process quite naturally is self correcting, to a large degree. Some artisanal type razorsmiths will go out of their way to create and accentuate a hamon. I don't see the point, myself, except to justify a higher price for greater knowledge.
 
A 15 degree bevel angle on a razor is inclusive. From one bevel face to the other. A 15 degree bevel angle on a knife is 15 degrees between one bevel face and the center of the bevel. The central plane of the blade. So a 15 degree knife equals a 30 degree razor. Except that there aren't any.

GENERALLY the entire blade is heat treated and tempered and the only differences in hardness are due to greater mass in the spine than the main part of the blade. This difference is of little consequence in honing. NO consequence, actually. Just hone it according to the method you choose following the regimen you like and the tools called for. The spine may be slightly softer due to shorter soak time at critical heat prior to quench. It may also be slightly harder due to the tempering process having full effect on the edge and not on the spine. I am not particularly experienced, let alone expert, at making razors so someone else will possibly correct me on that. However it also presents more face to the honing media and you are torquing the edge down ever so slightly as you hone, if you know your business. And as the spine wears, magically the spine's bevel face expands, slowing the incursion by the abrasive. When the honer doesn't do dumb stuff like hone on a bench (as a beginner) or hone on the shoulder or use excessive pressure or lay a finger on the blade or struggle to "control" the razor with two big meathooks, then the process quite naturally is self correcting, to a large degree. Some artisanal type razorsmiths will go out of their way to create and accentuate a hamon. I don't see the point, myself, except to justify a higher price for greater knowledge.

Ha! I did wonder that after I wrote that... as you can perhaps tell I’ve never actually measured the angle of a razor’s edge.
 

Steve56

Ask me about shaving naked!
Something not mentioned, if the edge flexes, and it will with surprisingly little pressure on a full hollow razor, the hone will scratch up the side of the razor above the bevel. You’ll see these scratches on razors if you look for them. It might be a good time to reiterate that a razor is not a knife and cannot be honed like one. I came to razors from Japanese knives, and TBH I would have been better off on razors not having any knife sharpening knowledge at all. Everything is bass ackwards on a razor; if it doesn’t cut well you can’t push harder, if the edge isn’t developing properly you use less pressure, not more, and so on. The only thing that knife sharpening and razor honing have in common is that you rub both of them on abrasives.

When I started with razors, I wondered why razor guys had all these coarse hones. Maintenance on a JKnife was 3-5k, and I rarely used the 1k. The reason is that you can’t push very hard on a razor, and if you’re doing chip removal or geometry correction you have to have coarse hones or you’ll spend the rest of your life fixing your razor.

Cost is another issue. Really fine stones that can finish a razor are expensive - a Shapton 30k is around $350. So why wear down a $350 stone when a $20 King will set your bevel just as well?
 
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