Breadknifing - waste of steel? time saver? Case study with 3D model and simulation

[TheBeast]

You may have heard that breadknifing your straight razor removes more material than just honing out the defects with lower grits and "traditional" or "normal" honing strokes. The debate whether it does or does not remove more material seems to be going on to this day. This "study" and simulation will prove, theoretically that the process of breadknifing with honing done afterwards removes the same amount of steel as if you would hone the defect away without breadknifing.

In this study I have proved that breadknifing a straight razor is not a waste of steel AT ALL.

Sure we could argue that you could flatten the edge too much, removing more material than is needed. But just as easily you could remove the frown with "normal" honing and forget to check if the edge is straight. Lost in thought, meditating while you hone away, your edge could have been straight and the bevel was set 50 laps ago. You are probably on a grit lower than 1k, so your steel loss will be the same as mine, if I over-do it on the breadknifing.

The only question is: who will have more patience to check for the straightness of the edge often enough to catch a perfect moment of a straight edge with zero steel wasted. And I could tell that I will stop breadknifing a little early and swith to 1k honing until the edge is straight and the bevel is set, losing zero steel in the process of breadknifing. I am also already at 1k with a bevel set, while you are still on 400 trying to remove the frown and get a straight edge. Now remember, you still have to get to 1k and remove 400 stria.

So therefore, it is my opinion that breadknifing with care is a time saver. I am not a patient man. Is it for everybody? Who am I to tell anyobody what gear to buy and what to do with their razors? I will do with mine as I see fit and good luck to everybody with their own blades. Let's all share the things we have learned while we spent quality time, deep in our beloved hobby.


But I'm confident and I have proof that breadknifing is not a waste of steel, at all. Please see the attachment for some cool pictures and let's consider this as an end to the debate on this topic. Share with anyone who is not sure about breadknifing. This is all you will need in terms of theory behind the amount of steel removed by this method compared to "normal" honing. Sure, real life situations are not perfect, our hand-eye coordination is not perfect. But breadknifing can be done without ZERO steel loss and here is why.

 

[JPO]

”breadknifing" and jointing are two different things. I thing the latter have been discussed lately. Jointing can be performed at different levels in the honing process. If done with care it should only take a few strokes to get the edge back.
Breadinifing to remove damage and frowns is a repair technique. You can also remove frowns by lifting the spine, if you don’t want to use tape or replace tape often to reduce wear on the spine.

 

[TheBeast]

”breadknifing" and jointing are two different things. I thing the latter have been discussed lately. Jointing can be performed at different levels in the honing process. If done with care it should only take a few strokes to get the edge back.
Breadinifing to remove damage and frowns is a repair technique. You can also remove frowns by lifting the spine, if you don’t want to use tape or replace tape often to reduce wear on the spine.

Yes. This is purely about breadknifing, since I have read a lot about how this is wasting steel.

About jointing I have also read that it's "wrong". But a farely similar principle applies since jointing will "kill the edge", making a flat surcafe, not a sharp V.

Again, this is purely to show that breadknifing does not remove more material then "regular" honing, if you are removing chips or a frown.

 

[Darth Scandalous]

I glanced at the pdf, I think you are more or less correct. I have dealt with chips both ways. I will say, when I breadknife out a chip, the subsequent honing to reestablish the bevel/spine plane always seems to take longer than I think it should. But that is probably just perception. I can see arguments for both ways. For instance, flat honing out a chip or frown on a coarse stone or a diamond plate can leave you with deep scratches that are a headache later. Where breadknifing the chip out and then honing on a less coarse stone sets you up nicely for the rest of the progression. On the other hand, working within the existing bevel/spine geometry can help avoid creating new geometry problems later. End of day, do it how you like.

Breadknifing out a smile is not something I would ever do, though.

 

[cotedupy]

You may have heard that breadknifing your straight razor removes more material than just honing out the defects with lower grits and "traditional" or "normal" honing strokes. The debate whether it does or does not remove more material seems to be going on to this day. This "study" and simulation will prove, theoretically that the process of breadknifing with honing done afterwards removes the same amount of steel as if you would hone the defect away without breadknifing.

In this study I have proved that breadknifing a straight razor is not a waste of steel AT ALL.

Sure we could argue that you could flatten the edge too much, removing more material than is needed. But just as easily you could remove the frown with "normal" honing and forget to check if the edge is straight. Lost in thought, meditating while you hone away, your edge could have been straight and the bevel was set 50 laps ago. You are probably on a grit lower than 1k, so your steel loss will be the same as mine, if I over-do it on the breadknifing.

The only question is: who will have more patience to check for the straightness of the edge often enough to catch a perfect moment of a straight edge with zero steel wasted. And I could tell that I will stop breadknifing a little early and swith to 1k honing until the edge is straight and the bevel is set, losing zero steel in the process of breadknifing. I am also already at 1k with a bevel set, while you are still on 400 trying to remove the frown and get a straight edge. Now remember, you still have to get to 1k and remove 400 stria.

So therefore, it is my opinion that breadknifing with care is a time saver. I am not a patient man. Is it for everybody? Who am I to tell anyobody what gear to buy and what to do with their razors? I will do with mine as I see fit and good luck to everybody with their own blades. Let's all share the things we have learned while we spent quality time, deep in our beloved hobby.


But I'm confident and I have proof that breadknifing is not a waste of steel, at all. Please see the attachment for some cool pictures and let's consider this as an end to the debate on this topic. Share with anyone who is not sure about breadknifing. This is all you will need in terms of theory behind the amount of steel removed by this method compared to "normal" honing. Sure, real life situations are not perfect, our hand-eye coordination is not perfect. But breadknifing can be done without ZERO steel loss and here is why.

Nice, cheers for posting! Look forward to having a proper read through on the train later.

I've heard breadknifing recommended quite a lot by some very experienced people. And done well I can't see any reason at all it would waste more steel than necessary, as your PDF I'm sure will explain in more detail.

(I did once make the mistake of breadknifing a yanagiba when restoring it, though tbf the geometry of yanagi is a lot more complicated than a straight razor. But yeah either way - don't do that. )

 

[TheBeast]

I glanced at the pdf, I think you are more or less correct. I have dealt with chips both ways. I will say, when I breadknife out a chip, the subsequent honing to reestablish the bevel/spine plane always seems to take longer than I think it should. But that is probably just perception. I can see arguments for both ways. For instance, flat honing out a chip or frown on a coarse stone or a diamond plate can leave you with deep scratches that are a headache later. Where breadknifing the chip out and then honing on a less coarse stone sets you up nicely for the rest of the progression. On the other hand, working within the existing bevel/spine geometry can help avoid creating new geometry problems later. End of day, do it how you like.

Breadknifing out a smile is not something I would ever do, though.

Breadknifing out a smile is just a posibility, I wouldn't do that either.

Exactly like you said, everybody should do it how they want to do it.

I just wanted to show that in Theory, it is not a wasteful Technique and I wanted to back up my claims with data. It was a fun afternoon doing that. Hopefully someone might enjoy the read and no longer have to Guess about the things that are shown in the PDF.

Nice, cheers for posting! Look forward to having a proper read through on the train later.

I've heard breadknifing recommended quite a lot by some very experienced people. And done well I can't see any reason at all it would waste more steel than necessary, as your PDF I'm sure will explain in more detail.

(I did once make the mistake of breadknifing a yanagiba when restoring it, though tbf the geometry of yanagi is a lot more complicated than a straight razor. But yeah either way - don't do that. )

Thanks for the heads Up on the yanagi! Let me know what you think Once you read through it.

 

[alex1921]

I have used breaknifing to remove frowns. Chips I have had only fairly small ones so simple honing would take them out.
Either way steel needs to be removed.

 

[Gamma]

The only way to bread knife, and not remove more steel than needed, is to go about 1/3, or 1/2 of way in, and then hone to a working bevel.
If someone bread knifes a blade to a flat, then hones, they take off more than needed. It happens. A lot.
It doesn't have to happen that way but it does happen.

When someone's skills aren't there or they are reading disinformation on the web and taking action without thinking things through first, all kinds of grinding can go sideways. Happens all the time. For no good reasons, a lotta 6/8s were turned into 4/8s over the years.

Just thinking about it, removing steel is removing steel and no matter what - the same amount of steel has to be removed, no matter how it's done. And if the 'mark' isn't missed, then the right amount of steel is removed.
User error exists though. big time... and that should be considered heavily, especially giving advice.

I think the main thing people rail about though, is the time to hone past the bread-knifed flat-edge into a usable bevel.
The fake workaround is to do an angled breadknife where you grind at a 45 deg angle to a midway point, then hone it out normally.
Again, it's all the same thing. If you grind correctly, it's six of one or half-dozen of another. X amount of steel has to be removed, how it is removed is irrelevant and I haven't found one way to be easier than another really.

I don't bread knife for two reasons, first, I've honed way more than my fair share of basket-case blades and have never found it necessary. I suppose at some point I might run into a blade that might be a candidate for grinding that way, maybe. But so far just honing works just fine. Ive done it a few time, just because I wanted to. Sort of a comparison thing.

Main reason I don't bother with it is that bread-knfiing leaves me with a fatter bevel. I''d rather just hone normally and let the geometry work itself out normally.

I've been asked wether or not to break-knife too many times to count. I've always suggested not to and the honing has always worked out just fine.

 

[MasterOfPups]

I would have thought that breadknifing would lead to a thinner bevel, since you aren’t working the spine down ?

 

[TheBeast]

I would have thought that breadknifing would lead to a thinner bevel, since you aren’t working the spine down ?

After breadknifing you are narrowing the blade width and in order to create a new edge that is closer to the spine with the same bevel angle, the bevels will be larger. This could be avoided to some degree with taped spine, but that would change the bevel angle.

If you would breadknife and hone without tape and put even pressure on the edge and the spine and your goal would be the same bevel angle, then the material removal will project itself in spine wear and bevel width - thicker bevel and thicker spine wear + thinner spine.

The sketch in the PDF shows why and the 3D model shows how.

Edit: the spine wear will be much thicker, the bevel width will be dependant on the geometry of the grind of the razor. But from experience, the more I hone a razor, the more I reduce the blade width and the thicker the bevel I get, especially after breadknifing.
GD66 after breadknifing - an experiment to remove a smile. Result - Huge spine wear and thick bevel.

Edit 2: this is actually a great Point. My 3D model started off with 1mm bevels and ended with 1.09mm bevels. I would say this was because my hand-drawn grind profile is not very close to most razors, that's why there was only +0.09mm difference. In my next experiment, I might cut off the toe and see exactly what is going on with the grind, and at what Point and why you get thinner/thicker bevels.