Razor sharpening class: Warp - how it affects a razor

[tat2Ralfy]

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?

Oh it matters, not only will it look crap, but the edge will be a little off here and there, and you run a risk of creating a frown too, a little variation in the bevel is fine, but a roller coaster bevel is not lol, what I do is try to visualise a strip down the side of my hone, the side the razor is on, say about 25-30mm wide, and use a rolling X stroke that keeps the blade contacting the hone on this strip, so you are in effect using a 25-30mm wide hone, the extra width of the actual hone doesn't effect this, because you are not using it, if you do this you should find the bevel is more even.

Ray taught me a superb method for straightening up a bevel, which he may like to share with you also.

I hope this helps
best of luck
Ralfson (Dr)

 

[maro]

That helps a lot. I remember that #10 is fairly wide so I was wondering how you do rolling X on such a hone.
Thanks.:thumbup:

 

[maro]

Sorry gents for bothering you again but the longer I think about it the less I understand. :blink:
I've even made a simplified drawing to get the point:

On the left the cross section of a perfect blade without a warp. On the right a blade with an excessive warp (to visualize it better).
How do you get equal bevels on the warped razor without raising its spine? What do I miss in my train?

 

[Bart]

Your drawings suggest that the warp is not affecting the spine in any way, which is not always true.
But at any rate, bevel evenness is irrelevant. Unevenness at the bevel is what compensates for warp. It is your friend, rather than your enemy.

I've been writing on a reply for you on and off during today. Nearly finished. I'll post later tonight.

Best regards,
Bart.

 

[Bart]

Without having a chance to read all replies, I will alaborate on your question a bit further, Maro.
First of all, it is important to realize that the warp in straight edged (non smiling) blades is usually within reach of a regular X-stroke. It will only show up as unevenness along the width of the bevel, typically in reverse correlation. "Reverse correlation" meaning that at the spot a bevel is wider on one side, it will be narrower on the other side of the blade. That's just the shape of the bevel compensating for the warp in the blade, which is a good thing. In severe cases (which rarely occur, and must be considered a defect) the warp is so outspoken that it no longer allows for the edge to exist in between both bevel boundaries. Or, put in other words, the bevel becomes so wide at one side of the blade, that it becomes non-existent at the other side (in fact, in spite of a good X-stroke such severly warped blades just aren't capable of touching the hone at that part of the blade). The solutions for these rare cases are: A. using a narrow hone, and B. changing the straight edge into a smiling one.

Which brings us to smiling edges. As illustrated, a smiling curve deals with the consequences of warp. But it compels us to add a rocking motion to the diagonal trafectory of the X-stroke. Obviously - and I blieve this answers one of your concerns - together with the portion of the edge that contacts the hone, also the corresponding spine part MUST make proper contact. Let's define some abbreviations, that divede a blade in 5 parts: T (tip) MT (middle-tip), M (middle), MS (middle-shoulder) and S (shoulder). A "rolling" starts with S in contact ant T raised. It ends with the opposite of that: T in contact and S raised. But with all three middle parts, the blade is flat on the hone. It stroke only shifts the pressure zone: from MS over M to MT. You could aim to keep the edge perpendicular on the hone, by angling the blade a bit back when the S-part is in touch and ending with the blade angling forward when the T-part receives attention. This is called the swooping stroke and it can be combined with a rolling motion.

Under no circumstances I advocate the so-called 45 degree stroke, and I deiberately left it out the article that describes the various honing strokes. A word of explanation: during the "S" and the "T" part of the roling stroke, only a small part of edge and spine is in contact with the hone. With an heavily angled stroke, the edge does not mate with its normal counterpart at the spine, but on a spine-part diagonally across. The "normal" counterpart is located off the hone, below the surface, while the rest of the spine is raised above the hone. It isn't too difficult to see that the resulting bevel angle at will be lower than the normal bevel angle. That also explains why on smiling razors that are honed with an exaggerated swoop, we usely see a widened beve at the shoulder and often also at the tip. On a straight (non-smiling) edge, honed without rolling stroke, this does not occur, yet there is not one single reason why a 45 degree angle would offer any honing advantage.

----
Some additional remarks after catching up with the rest of the thread:

45-degree angle: yes it might help to keep a razor stable on a narrower hone, but doing so it takes away the advantage of a narrower hone, which is to follow the curve (smiling or warped) of the edge a bit better.

Frown: the best recipe to develop a frown is to hone a razor with slight warp in the middle, straight across a flat hone. Or any other attempt to force "even" bevel faces on a warped razor, for that matter.

Methods for straightening up a bevel: great for correcting (years of) honing error, but rest assured that at a given edge curve (smile)on a razor with given shape (warp and/or uneven grind), the bevel shape is defined by these parameters and only these. Yes, you can make one side wider in favor of the other, or vice versa, but the general bevel shape will stay the same. It's not something to worry about.

Best regards,
Bart.

 

[Matt]

(...) But at any rate, bevel evenness is irrelevant. Unevenness at the bevel is what compensates for warp. It is your friend, rather than your enemy. (...)

Frown: the best recipe to develop a frown is to hone a razor with slight warp in the middle, straight across a flat hone.

Hmmm, that got me a little puzzled? One of my Wapis is warped a little, which is clearly seen on the bevel - on one side (going from tip to shoulder) it is W-N-W (wide, narrow, wide) when turned over it's of course N-W-N. My guess was that it's perfectly OK, but now the part about the frown got me wondering. Should I not hone this Wapi flat and rather turn to rolling stroke? As of now it doesn't show any signs of frown, but well, it didn't have enough time to do so - it saw a stone, say, 3-5 times, at most

kind regards,
Matt

 

[maro]

Your drawings suggest that the warp is not affecting the spine in any way, which is not always true.

That's all I was able to squeeze out of MS Power Point with my gift to graphic arts.

But at any rate, bevel evenness is irrelevant. Unevenness at the bevel is what compensates for warp. It is your friend, rather than your enemy.

Note taken.

I've been writing on a reply for you on and off during today. Nearly finished. I'll post later tonight.

Thanks a lot for your time spent on writing it! :thumbup: I've gone through it and finally (I hope) understood the "warp affair". B)

This is called the swooping stroke...

Do you mean the swaying X-stroke as described in Sharpening Academy or something else?

 

[randydance062449]

Tat2Ralfy....thats a great animation of the rolling X stroke! Thanks a bunch.

 

[tat2Ralfy]

Tat2Ralfy....thats a great animation of the rolling X stroke! Thanks a bunch.

you are very very welcome, however you need to Thank Sir Bart, I took it straight from the Sharpening Academy on this site :thumbup:

 

[randydance062449]

OOPS!:O

 

[Bart]

Do you mean the swaying X-stroke as described in Sharpening Academy or something else?

Yes, indeed. I got caught up with my own terminology.:

(...) But at any rate, bevel evenness is irrelevant. Unevenness at the bevel is what compensates for warp. It is your friend, rather than your enemy. (...)

Frown: the best recipe to develop a frown is to hone a razor with slight warp in the middle, straight across a flat hone.

Hmmm, that got me a little puzzled? One of my Wapis is warped a little, which is clearly seen on the bevel - on one side (going from tip to shoulder) it is W-N-W (wide, narrow, wide) when turned over it's of course N-W-N. My guess was that it's perfectly OK, but now the part about the frown got me wondering. Should I not hone this Wapi flat and rather turn to rolling stroke? As of now it doesn't show any signs of frown, but well, it didn't have enough time to do so - it saw a stone, say, 3-5 times, at most

kind regards,
Matt

If that Wapi carries a straight (non smiling) edge, you can hone it with "flat" X-strokes. If your honing pressure is even, it will not develop a frown. I was merely pointing out that honing straight up and down a wide hone is more likely to promote the development of a frown on such a "bulging" (warped) razor, than a good X-stroke. Although most people who opt to hone without X-stroke do so in fear of frowns and tapering blades.

But at any rate, a frown should never develop during one sharpening session, not even in 2 or 3 full honing sessions. A frown is always the result of a lot of sharpening. I know Maro managed to get a frown on his Dovo, during his very first honing attempt, but in his inexperience at that time, he removed way more steel than necessary to sharpen a razor.
[warn]Even if a razor has no bevel to start with, the steel at the border of the blade can still serve to become the tip of the to new bevel. A sharpening session never requires the removal of more than a few steel grains of the blade width. Unless there are chips missing. In that case, the "first" attainable edge lies at the bottom of the largest chip.[/warn]

The very slow alteration of the edge curvature over many sharpenings, gives you plenty of time to take corrective action.

Best regards,
Bart.

 

[maro]

But at any rate, a frown should never develop during one sharpening session, not even in 2 or 3 full honing sessions. A frown is always the result of a lot of sharpening. I know Maro managed to get a frown on his Dovo, during his very first honing attempt, but in his inexperience at that time, he removed way more steel than necessary to sharpen a razor.

Yeah, it took me more than 4 hours of continuous honing so everyone can count how many times an error has to be repeated to get a frown of 0.5mm depth. :
My skills have improved slightly since then but, as it has nothing to do with a warp, I'll post some pics about my (presumable) progress in a separate thread.

 

[yohannrjm]

Thanks everyone for this thread!!

I just received my first razor with a significant warp. After thinking about it myself (with no input from the internet ), I started honing it, thinking I'd figured out how to hone it. Luckily, I have a 1.5" wide coticule, as I noticed that it was very hard to get the concave side honed properly on my DMT's (they're wide). I managed to set the bevel on the DMT's, but it took some work.

After going through my honing progression, I figured out that the razor was super-sharp over about 2/3 of its length (the toe was not sharp). So I went back and started over. After going through my progression again, I got the same results.

After reading this thread, I'm glad to see that others approach this issue the same way I do - at least my approach was correct (rolling X on the convex side, regular X on the concave side - with an effort to get the whole length of the blade to touch the hone). It is most likely that I need to work on my stroke so that I get the toe to hone properly. I believe that with my stroke stopping with about an inch of the blade (at the toe) still on the hone, the warp is lifting some of the blade off the hone.

It's a small blade (4/8"-), so there's no significant help from the flexing of the blade.

Back to work. :thumbup:

EDIT: Figured it out. Side of the hone was nice and narrow.