Thread: The science of pyramids?

Originally Posted by Redwoood

While Nenad's images look amazing, I believe they are not 100% accurate (at least not for a smile created through honing) because the spine seems to be of the same thickness throughout. I would assume that the spine should be thickest in the middle and tapering out towards heel and toe.

Nenand probably exaggerrated the smile to demonstrate his point. That razor looks more like a scimitar. But the spine is accurate. It should be the same thickness along its entire length, if it is honed properly.

I believe that the smile is a self-regulating mechanism. The more pronounced it is, the higher the tendency of the hone to take away the belly, and thus, reduce it. You would have to put in a lot of effort (maybe including lifting the spine) in order to create a very pronounced smile.

This is true, but a flat hone will handle a certain amount of smile. It's only supposed to be slight. You would notwant to lift the spine. You can vary the pressure to achieve the smile. There's a description of this in the barber manual.

Once you start honing straight with an angle and heel leading, you cannot go back to simple straight honing because the heel portion of the spine would not hit the hone in the former and would subsequently lift the heel part of the edge in the latter.

Remember, you're honing so the bevels lie in a plane. The only thing the leading heel does is make the scratch lines at an angle to the edge, instead of perpendicular to it (for straight across). I, in fact use both. I might use a wide hone to firsr set up the razor and then maintain it witha barber hone. So, I start out honing straight across heel first, and I refresh by using the x-pattern. As I said, you get the same scratch lines.

Originally Posted by Joe Lerch

Nenand probably exaggerrated the smile to demonstrate his point. That razor looks more like a scimitar. But the spine is accurate. It should be the same thickness along its entire length, if it is honed properly.

That would make it difficult to achieve a smile as I understand it.
In order to achieve a smile you have to hone away more (with more pressure?) of the edge at the toe and the heel. Now, if you hone more of the edge, you also remove more material off the spine. If your spine is of perfectly equal thickness, you would have a hard time reaching the toe portion of the edge and it would be impossible to reach the edge near the heel. Besides, your bevel would have a steeper angle at heel and toe.

Remember, you're honing so the bevels lie in a plane. The only thing the leading heel does is make the scratch lines at an angle to the edge, instead of perpendicular to it (for straight across). I, in fact use both. I might use a wide hone to firsr set up the razor and then maintain it witha barber hone. So, I start out honing straight across heel first, and I refresh by using the x-pattern. As I said, you get the same scratch lines.

Maybe I didn't express myself properly the first time around. If you hone on an angle with the heel leading, there will be a portion of the heel-spine which does not touch the hone. The greater your angle, the longer this portion will be.
Now if you do this for a while, the rest of the spine will diminish in thickness, while the in-the-air portion will not.
If you ever wanted to switch back to a straight, edge-perpendicular-to-honing-motion technique, you would end up with the problem that the in-the-air part of the spine would now be thicker than the rest of the spine, and the uneven thickness would lift the heel portion of the edge up. So you better stick to heel-leading if you've done this for some time.

I'm not trying to stir up trouble, just trying to see if my understanding of honing is sound.

Redwoood

[quote=Redwoood]

That would make it difficult to achieve a smile as I understand it. In order to achieve a smile you have to hone away more (with more pressure?) of the edge at the toe and the heel. Now, if you hone more of the edge, you also remove more material off the spine. If your spine is of perfectly equal thickness, you would have a hard time reaching the toe portion of the edge and it would be impossible to reach the edge near the heel. Besides, your bevel would have a steeper angle at heel and toe.

I see what you meant. If you start with a straight edge and spine, and and create a smile, that will happen. The spine bands will be wider at the ends. My new Fillie was manufactured with a smile and it has a straight spine of uniform thickness, with uniforly thick bands and bevels. Some of the older razors, like some W&Bs have a smiling spine of uniform thickness. I assume they were gound with a smile. In this cae the bands and bevels are uniform.

Maybe I didn't express myself properly the first time around. If you hone on an angle with the heel leading, there will be a portion of the heel-spine which does not touch the hone. The greater your angle, the longer this portion will be. Now if you do this for a while, the rest of the spine will diminish in thickness, while the in-the-air portion will not. If you ever wanted to switch back to a straight, edge-perpendicular-to-honing-motion technique, you would end up with the problem that the in-the-air part of the spine would now be thicker than the rest of the spine, and the uneven thickness would lift the heel portion of the edge up. So you better stick to heel-leading if you've done this for some time.

It doesn't seem like you're visualizing the heel leading honing correctly. It is done on a wide hone and is exactly the same as straight across honing, in that the entire edge is hone at one time. The only difference is that the heel leads. Pressure is still uniform amd the entie edge spends the same amount of time on the hone. The spine and bevel are taken down uniformly, and to the naked eye, the blade looks the same whether you use the x-pattern, straight across, or heel leading. The difference is that heel leading also looks the same as the x-pattern microscopically, whereas straight across has scratch lines that are perpendicular to th edge. There is no problem moving back and forth between honing styles. With heel leading you don't even change the scratch pattern.

Originally Posted by Joe Lerch

It doesn't seem like you're visualizing the heel leading honing correctly. It is done on a wide hone and is exactly the same as straight across honing, in that the entire edge is hone at one time. The only difference is that the heel leads. Pressure is still uniform amd the entie edge spends the same amount of time on the hone. The spine and bevel are taken down uniformly, and to the naked eye, the blade looks the same whether you use the x-pattern, straight across, or heel leading. The difference is that heel leading also looks the same as the x-pattern microscopically, whereas straight across has scratch lines that are perpendicular to th edge. There is no problem moving back and forth between honing styles. With heel leading you don't even change the scratch pattern.

Ah ok, I got you know. You have to make sure that the shoulder/shank is always right at the edge of the hone. Although even then, there would be a tiny portion of the spine that doesn't hit the hone because of the height of the shoulder/shank ( h * tan \alpha, if the shank is h high and \alpha is the heel angle). But that would probably be very small indeed.
The scenario I described happens when you hone with the blade's edge close to the edge of the hone. This would happen if, for example. you hone is not quite wide enough for straight across, but wide enough for heel-leading across.

Thanks for your explanations, Joe.

Redwoood

Stay away for a few days and you guys have all the fun.

First: Nenad ... YOU ROCK!!! Super Diagrams. Now do a few with a heel leading stroke where the heel is on the hone at the beginning of a stroke and the tip at the end and you will present the Rolling Hone method better than words ever could.

About spine shape: It is not the only factor in determining the edge shape. Variable pressure through honing will do it and even on a flat spine an incredible smile can be achieved, much like Nenad's illustration. Ask, Ed. I think one of my blades (the Henkels in my Gallery folder) ended up in his hands. (how's the scales comming there, Ed?)

And I will contradict Joe (AGAIN!?!?!?) on the efficiency of a curved, even heavily curved edge. My face isn't flat so my razor doesn't need to be, and with a wide smile I can use an almost insane cutting angle (that's toe leading the heel on my face for n00bs) without fear of nicks or cuts.

Flattening the edge of a curved spine razor is a crime though. Honed Ed's Wolstenholm and it was uncomfortable to work the flat edge shape against the curved spine. Okay, so that's not a crime, but it's inconvenient.

X

Originally Posted by xman

About spine shape: It is not the only factor in determining the edge shape. Variable pressure through honing will do it and even on a flat spine an incredible smile can be achieved, much like Nenad's illustration.

But Nenand is right when he points out that you can't maintain an extreme smile on a flat surface. You only have to think in terms of putting an even chamfer on the edge of a coin. It can't be done without changinging the contact point.

On the other hand, the baber manual only speaks in terms of a slight smile, which can be done. Actually, it only warns against a frown (which is said to give a rough shave), so a straight edge is within its recommendation, but an extreme smile rather than a slight one is not.

And I will contradict Joe (AGAIN!?!?!?) on the efficiency of a curved, even heavily curved edge. My face isn't flat so my razor doesn't need to be, and with a wide smile I can use an almost insane cutting angle (that's toe leading the heel on my face for n00bs) without fear of nicks or cuts.

I agree with the efficiency of a smile, even if it's only two tapers with a smooth transition between them (which is what the barber manual describes). It's all a matter of degree. Look at Nenands diagram and think in terms of putting an edge on a 2" diameter disk (as an extreme example). How much of it will shave your face? And if you apply enough pressure for two points an inch apart to shave, what happens to the pressure in the middle? I don't think I've seen any razors in good shaving condition with other than a slight smile.

The effect of the smile is to provide an edge that's at an angle to the whiskers in most locations, so you're not just doing a push cut. I'm trying to visualize why a frown would feel rough, and it seems tha it's because the edge is pushing the skin toward its center, where it bunches up and gets cut or abraded. You'll have to convince me that a smile is any better than a straight edge used at an angle or with a slight scything motion. A guillotine has a straight edge cutting at an angle, and it's pretty efficient.

Flattening the edge of a curved spine razor is a crime though.

If you think about it, it produces an edge in which the bevel angle varies along the edge. I'm trying to visualize it and it seems that the spine band thickness would also need to vary.