Thread: I could use some advice here

Yes, I have seen the wiki on the rolling X strokes, thanks.

I will do that and I will let you know how it goes

Math time: the intersection of two planes is a straight line.

That means that no razor with a smile can have the whole edge on the hone at a single moment. The bigger the smile the bigger the rocking.
It may or may not be warped. Also poor grinding or previous abuses that change the spine thickness or blade width typically make things worse.

The solution of course is to hone each section of the edge subsequently, that's what the rocking/scything/whateveryouwannanameit stroke is - you drag the edge across the hone from the heel to the tip throughout the stroke.

Since you breadknifed the razor you'll have a lot of work to do. Being short on experience I'd say at least 10 hours before you get it to shave could be more though. You will definitely need to start with a much coarser hone than the one you have on the photos.

Originally Posted by gugi

Math time: the intersection of two planes is a straight line.

That means that no razor with a smile can have the whole edge on the hone at a single moment. The bigger the smile the bigger the rocking.

I am sorry but that statement is wrong. You are seeing the blade as a single plane.

A curve is made of interjections of lines at different angles. The same applies when talking to planes. A curved plane is made from interjections of straight planes at different angles.

Now, if I can make the edge fully centered in relation to the spine thickness, there will be a point where the edge and the spine share the same plane, and that plane is where the whole edge makes contact.

I can't explain better as English is not my native language, but I hope you get my idea! That if 2 straight lines (edge and spine) can have contact on a hone (flat surface), a curved line (if properly done) can too, as the curve is just a sum of straight lines.

Originally Posted by Hammett

I am sorry but that statement is wrong. You are seeing the blade as a single plane.

A curve is made of interjections of lines at different angles. The same applies when talking to planes. A curved plane is made from interjections of straight planes at different angles.

Now, if I can make the edge fully centered in relation to the spine thickness, there will be a point where the edge and the spine share the same plane, and that plane is where the whole edge makes contact.

I can't explain better as English is not my native language, but I hope you get my idea! That if 2 straight lines (edge and spine) can have contact on a hone (flat surface), a curved line (if properly done) can too, as the curve is just a sum of straight lines.

I'm not going to invoke Euclid to help me with this. I really don't care to apply mathematical concepts to what I can see with my own eyes.

If the spine is straight, meaning that it can lie flat on the hone when the blade is held parallel to the hone, then hold the razor on the hone in that position. Now hold the blade edge so that it is held parallel to the hone at a distance that is half the total thickness of the spine

At that point, the entire length of the spine is touching the hone and none of the blade is touching the hone and the blade edge is parallel to the hone.

Now, lower the edge down to the hone. A smiling edge will touch the hone in only one region, not the entire length of the edge.

I was talking theoretically, of course!

I have an old W&B with a smile and when I put it on the hone, 95% of the edge makes contact at the same time.... Of course manufacture slight deformations, spine wear, metal deformation through the years, etc will change the fact that it is possible to have a smile edge to make full contact with a hone.

On the practical side, yes, you're absolutely right that it is very odd to have a smiling edge that makes full contact across the edge at the same time, thus the need for rocketing X strokes.

Originally Posted by Hammett

On the practical side, yes, you're absolutely right that it is very odd to have a smiling edge that makes full contact across the edge at the same time, thus the need for rocketing X strokes.

If the edge is appropriately contacting the hone, what is the resoning re the need for exotic sharpening strokes?



ed

Because the edge has a smile and second, because the blade rockets on the hone, hence the need for the "exotic" sharpening strokes.

Originally Posted by Hammett

I am sorry but that statement is wrong. You are seeing the blade as a single plane.

Uhm, no, the statement is correct, your understanding of math isn't. A 'curved plane' is called 2-dimensional space or surface and generally is not made from interjections of planes. If the 2-dimensional space is a manifold yes, locally it resembles Euclidian space, which is what you're thinking. An ideal edge is obviously not a manifold. the two sides of the bevel are two completely different tangent spaces attached to the same point/line.

Originally Posted by Hammett

That if 2 straight lines (edge and spine) can have contact on a hone (flat surface), a curved line (if properly done) can too, as the curve is just a sum of straight lines.

First there are three lines, the edge and the spines on the two sides of the razor. Second straight doesn't describe your razor.

Any three points form a plane, whole lines belonging to the same plane puts a lot of restrictions. If your edge (a line) and the spine on one side of the razor (another line) belong in a single plane, the spine on the other side of the razor (third line) is not in the same plane and therefore cannot be in a plane with the edge.

It the math is too abstract you can take a piece of paper and convince yourself that you cannot fold it to form a 'smiling' edge without crumpling or tearing it.

BTW English isn't my native language either, hence using math which is invariant, to explain your issue.

Originally Posted by gugi

It the math is too abstract you can take a piece of paper and convince yourself that you cannot fold it to form a 'smiling' edge without crumpling or tearing it.

True, I cannot make a smile from a single piece of paper, but I can get a bunch of papers and make a smile, and that's my point.

Originally Posted by gugi

Any three points form a plane, whole lines belonging to the same plane puts a lot of restrictions. If your edge (a line) and the spine on one side of the razor (another line) belong in a single plane, the spine on the other side of the razor (third line) is not in the same plane and therefore cannot be in a plane with the edge.

Sorry, I am not a math geek (though I understand what you say). I am speaking of what I am remembering from primary school, hence I admit I might be wrong.

But, if we can imagine a half-moon 3D object and we cut it with 2D planes at any angle, we will end up with 2 edges made by the intersection of the 2 planes and the object. If we can narrow those 2 edges to a minimum (just a line), that new edge will share the same plane from the 2 sides of the spine.

Originally Posted by Hammett

True, I cannot make a smile from a single piece of paper, but I can get a bunch of papers and make a smile, and that's my point.

And that's the reason why you cannot have a smiling edge lay on a flat hone. If you can make it with a single piece of paper you'd be done.

Originally Posted by Hammett

But, if we can imagine a half-moon 3D object and we cut it with 2D planes at any angle, we will end up with 2 edges made by the intersection of the 2 planes and the object. If we can narrow those 2 edges to a minimum (just a line), that new edge will share the same plane from the 2 sides of the spine.

If I understand correctly your proposition, the part in red is what you cannot make happen. I mean you can make it in a single case and that is when the two planes coincide, but that's not a razor.

Anyways, the whole point of talking about the math is to convince you that there is only one way to get a shaving edge on that razor. If you aren't convinced you'll still have to do it the only possible way, but it may take you a lot of time trying to make something happen that is impossible to happen.
You can do x-pattern strokes, you can do scything strokes, rocking strokes, they accomplish the exact same thing which is to abrade metal from every section of the bevel, one at a time. I personally find it easiest to focus on the goal and the means are just whatever it is necessary to achieve it. Of course, other people prefer to use set prescriptions without worrying too much what exactly is happening and that can get them to the same end too.

All I'm saying is that if getting into the math is becoming a distraction it may be better to refocus back on how to sharpen that razor.


And yes, I've got a proven record as a math nerd, my math skills put me somewhere in the top 0.05% of people. I suppose just the fact that I calculated it gets me a third of the way there