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Razor sharpening class: Warp - how it affects a razor

Bart

Well-Known Member
Gentlemen,
It has come to my attention that few people understand about warp, and how it affect the sharpening of a razor. First allow me to tell something that may come as a surprise. Straight razors are rarely straight. This is due to the hardening process of the the razor blanks. The blade is heated to high temperature and than quenched in a bath, to quickly cool it, which "freezes" the steel structure without giving it time to relax. The result is hard and resilient, yet brittle steel. Too brittle, hence during the next step the blade is tempered, in order to release stresses and regain some ductility. Needless to say, that all stresses occurring and being relieved during this part of the production process sometimes alters the shape of the blade a bit. The result is a blade slightly out of true. This is further corrected during the grinding process, but even so, no straight razor blade is mathematically straight. This was one of the reasons why razors were produced with a smiling curve at the edge, as I'm about to illustrate. But, as smiling edges take some additional skills to sharpen them well, and perhaps because straight edges might be easier to produce, a lot of modern razors come with a straight edge.

Time to show a drawing:

[img=800]http://www.coticule.be/tl_files/barts_pics/blade&edge_conditions.jpg[/img]

At the top left, we see a razor without any significant warp, produced with a straight (non-smiling) edge. This is what many people consider to be a perfect razor. But is says nothing about the edge it is capable to take, because, that is all in the steel. It is also the kind of razor that invites inexperienced honers to push a razor up and down across the hone. That should work, in this case, although years of honing will probably introduce unevenly honed spine and edge parts, because whatever unbalance in pressure and honing stroke is repeated over and over again at the same spot.
Next, we see two drawings of a warped razor. It's the same warp both times, the razor turned over. You can see how at one side, only the middle part of the edge will touch the hone and at the other side the heel and tip will make contact. Obviously, I have exaggerated the drawing for clarity. This razor requires the X-stroke on one side and the rolling X-stroke at the other. By shifting the points of contact at the side of the hone, all of the edge will at some point during the stroke touch the hone. In a manner of speaking, the hone follows the curve in the blade. In no way, this must be considered a defect, because: 1. a lot of modern razors would need to be considered defect. And 2: once sharpened these razors shave perfect, because, as mentioned, the quality of the edge capable is all about the steel.
Only in rare cases a blade can be so severely warped that it becomes very difficult to sharpen in correctly. I have only encountered such a razor once, and with a very narrow hone and a good X-stroke I managed to get it sharpened after all. And it turned out to be an exceptionally smooth shaver. So smooth that I honed with the narrow hone for weeks, because I thought the magic was in the hone.

On the second row, at the left, we see a razor without any significant warp again. This time one with a smiling curve at the edge. When put on the hone, only the middle part of the edge makes proper contact. Please pay notice how much this situation resembles that of the top right (straight edge, warped blade). Also this blade can't be sharpened without a rolling X-stroke.

The final images both show the warped condition of a razor with smiling edge. On one side of the blade, the smiling edge overrules the "frown" of the warp. This is the reason why no one ever notices warp in a smiling razors. One needs to adopt a rolling X-stroke anyway, so the warp goes unnoticed. At the opposite side of the blade, the warp amplifies the smile, which just calls for a bit more outspoken roll in the stroke.

Thank you for your attention.

Kind regards,
Bart.
 

garyhaywood

Well-Known Member
bart so if one side is making full contact with x stroke. The other side the heal and toe are not making full contact. Would you use a roll x on one side and a flat x on the otherside. so basicly one side rolling x and on the way back flat x. I have come across this . so i have just rolling x on both sides, i have considerd doing just that flat x one side then roll the other . I just was'nt sure?
 

Bart

Well-Known Member
randydance062449 said:
This is a very useful and accurate post. I completely agree with you. Well done.:thumbup:
Thank you Randy, coming from a seasoned expert, these words mean a lot to me.

garyhaywood said:
bart so if one side is making full contact with x stroke. The other side the heal and toe are not making full contact. Would you use a roll x on one side and a flat x on the other side. so basically one side rolling x and on the way back flat x. I have come across this . so i have just rolling x on both sides, i have considered doing just that flat x one side then roll the other . I just wasn't sure?
On razors with smiling edge, I always need a rolling X. But on warped razors with a straight edge, yes, I often need the regular X-stroke on one side and a rolling X-stroke on the other. With many honing hours on the counter, I don't really have to think about it. I always make a few slow strokes, paying careful attention to the ripple of fluid, right in front of the edge. That sort of "calibrates" my stroke for that razor. I regularly slow down while honing, to check if I 'm still making my strokes right.
I guess this is one of those things that many experienced honers get right without putting much thought in it.

Best regards,
Bart.
 

garyhaywood

Well-Known Member
To be onest there has been times when the ripple is even all the waay but i have found that a tiny part of the cutting edge is not hitting the hone. As the heal is on and of the hone so qquik i also find that the ripple hard to judge at the heal. And in many cases looks like its on the hone when it realy is'nt. This is why i use marker as well as wathching the wave. Unless there is a real bad warp then yes i could easily spot that. The way the water runs up my edge is good for me to no my stroke is nice and even. In a realy dull blade even if its flat i normaly start with the heal down first as it gets less time on the hone other wise i find my heal's are not as sharp as the rest of the edge.
 

Bart

Well-Known Member
I don't hesitate to work on part of the edge (notoriously the heel and toe) if stays behind. Honing really is listening to the hone and reading the edge all the time. And respond with proper action to what it says. But that can only be learned with experience. Someone pointed out to me that in the
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(don't mind the CrO honing part, that's outdated), you see me doing the weirdest things during the bevel correction stage, as if I'm just doing something random. But it's actually all dictated by how the edge was developing. A lot of TPT's are edited out of that video. That test actually deserves more attention on this forum. During the bevel stages, I couldn't do without it.

Bart.
 
Bart, your use of the term " calibrating my stroke" is spot on.
Starting with slow strokes, analyzing the fluid movement, and frequently testing with the TPT during the honing process and other tests like a microscope or HHT helps me gauge my progress.

I agree that a warped blade with a straight edge is the most problematic. In addition to what you have mentioned here I make use of angling ( tilting)( heel leading to a greater or lesser degree) the blade to achieve a better contact.
 

PA23-250

Well-Known Member
Great post; really should go in the sharpening academy eventually!

Funny thing is, some guys don't like the rolling X, claiming it leads to inconsistent pressures being applied & prefer to lead w/ the heel instead. I've found that can work up to a point (maybe not so much w/ really warped blades), but my barber's W&B had such a heavy smile, if I didn't roll, there's no way the heel would have ever made contact w/ the hone whatsoever! Ended up being a super-close shaver, too. In practice, I always roll a bit after watching the fluid.
 

garyhaywood

Well-Known Member
I;ve tryed the 45 degree angle,that lynn recomends , and it's never worked for . I find it still leaves the toe and heal behind.
 

Paul

Well-Known Member
garyhaywood said:
I;ve tryed the 45 degree angle,that lynn recomends , and it's never worked for . I find it still leaves the toe and heal behind.

45 degree angle works quite well for me in that it reduces, but certainly doesn't eliminate, the tilting required to execute a good rolling X stroke
 

Smythe

Well-Known Member
The 45 degree (heel leading) helps with honing in a number of ways. If you use a narrow hone it will make more efficient use of the surface to sharpen the edge. It’s also easier to keep the blade flat because at that angle you are less likely to lift the spine. It also helps prevent a frown on a straight edge blade… In fact, when bread-knifing is the best way I know to remove a frown… But this may be off topic.

But I can guarantee you the rolling stroke will sharpen almost any edge.
“When you can’t beat them, then join them”. I cannot straighten a warp so I have been grinding a slight smile in “some" of my warped razors just so I can roll the stroke to easily sharpen the edge… it works.
 

garyhaywood

Well-Known Member
richmondesi said:
garyhaywood said:
I;ve tryed the 45 degree angle,that lynn recomends , and it's never worked for . I find it still leaves the toe and heal behind.

45 degree angle works quite well for me in that it reduces, but certainly doesn't eliminate, the tilting required to execute a good rolling X stroke

I do agree it does reduce i should of said
 

garyhaywood

Well-Known Member
I naturaly even when flat honing tend to find it more comfortable if start with a slight 45 degree angle. Its hard to explain but my heal kinda of leads and my toe finishes in front at the end of my hone
 

tat2Ralfy

Well-Known Member
garyhaywood said:
I naturaly even when flat honing tend to find it more comfortable if start with a slight 45 degree angle. Its hard to explain but my heal kinda of leads and my toe finishes in front at the end of my hone

I do too, I find it more natural that having the blade straight across the hone, and I always give it a little roll
 

maro

Well-Known Member
OK guys, now you baffled me completely. :blink:
From Bart's initial post and your comments it looks like regular X-stroke is actually useless (as there are almost no straight_blade-straight_edge razors) and you have to use rolling X every time anyway.
Why to bother with the thickness of the spine and the correct angle? It's almost a free-hand honing (especially with a wide stone) anyway... :confused:
 

rayman

Well-Known Member
maro said:
OK guys, now you baffled me completely. :blink:
From Bart's initial post and your comments it looks like regular X-stroke is actually useless (as there are almost no straight_blade-straight_edge razors) and you have to use rolling X every time anyway.
Why to bother with the thickness of the spine and the correct angle? It's almost a free-hand honing (especially with a wide stone) anyway... :confused:


This is certainly an unusual statement. I think after you have had more experienc you will find out that there are many different types of edges to work with, and yes, even flat ones too. I even run into "S" patterns sometimes that drive me insane. The point Bart is trying to make is that the "X" pattern can be used to take care of many different situations including, but not limited to a warped edge.

I like to finish my blades on a 25mm hone now so it compensates for any imperfections in the configuration of the edge. Even if the blades edge is perfectly flat I still use an "X" stroke on the blade.

Ray
 

maro

Well-Known Member
rayman said:
I think after you have had more experienc you will find out that there are many different types of edges to work with, and yes, even flat ones too.
Well, I'm a total newbe with close to zero experience. I don't deny. :blush:
That's why I try to understand the "mechanics" of razor honing and got confused. :-/

I'm the proud owner of #26 from the Vault so with some experience it shouldn't be a big deal to do rolling X, but how to do that on the wider stone without lifting the spine?
 

rayman

Well-Known Member
maro said:
rayman said:
I think after you have had more experienc you will find out that there are many different types of edges to work with, and yes, even flat ones too.
Well, I'm a total newbe with close to zero experience. I don't deny. :blush:
That's why I try to understand the "mechanics" of razor honing and got confused. :-/

I'm the proud owner of #26 from the Vault so with some experience it shouldn't be a big deal to do rolling X, but how to do that on the wider stone without lifting the spine?

Actually, once you start doing the roling-x you do lift the spine but it is more like you just think about it and it happens rather than actually lifting it and watching it move.

Ray
 

tat2Ralfy

Well-Known Member
maro said:
I'm the proud owner of #26 from the Vault so with some experience it shouldn't be a big deal to do rolling X, but how to do that on the wider stone without lifting the spine?

The spine stays in contact with the hone at all times, you tilt the razor so the toe is slightly off the stone and as the stroke progresses you bring the toe end down and slightly lift the heel.

We are talking slight here, no yawning gaps, it is very very important that the edge still contacts the hone on a fairly wide strip, if you tilt the razor too much the small contact area will dull the edge, it looks like this:



maro said:
Why to bother with the thickness of the spine and the correct angle? It's almost a free-hand honing (especially with a wide stone) anyway...

Because the spine doesnt leave the hone, its important to use this as it sets the angle of the bevel, and ensures that the bevel is always worked at that angle, sure you could in theory go freehand and not rest the spine on the hone, however 2 major problems will then arise:
1, the bevel angle will be too steep, unless you are honing a wedge, or a blade that has enough spine wear to need tape.
2, unless you are very very very very skilled, you simply will not be accurate enough to work the bevel efficiently, true most knifes are honed "freehand" in this respect, that alone is a skilled task, and even the best honed knifes dont come close to a razors edge when it comes to that tiny tiny strip that forms the very edge. on a straight razor its thinner than a rizla.

Hope this helps
Regards
Ralfson (Dr)
 

maro

Well-Known Member
tat2Ralfy said:
The spine stays in contact with the hone at all times, you tilt the razor so the toe is slightly off the stone and as the stroke progresses you bring the toe end down and slightly lift the heel.
That's pretty clear to me now. :thumbup:
tat2Ralfy said:
Because the spine doesnt leave the hone, its important to use this as it sets the angle of the bevel, and ensures that the bevel is always worked at that angle, sure you could in theory go freehand and not rest the spine on the hone
OK, free-hand honing was a bit of exaggeration. ;)
My main concern here is that, if the blade is warped, it will not keep the angle with a spine resting on the hone. On the warp it will be bigger (or smaller) depending on the direction of the warp. Or maybe the difference doesn't matter?
 
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