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Breadknifing, that delicate subject.

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How to breadknife and upset 90% of the membership.


Awhile back in time, I had occasion to show a barber [ not an SRP member ] how to remove a nasty chipout in a blade by breadknifing on a DMT 325 grit diamond plate. What makes my method a bit unique is that I stand the blade up vertically at an 80 degree angle and drag the blade edge basically from one end of the plate to the other end of the plate, then flipping the blade to the opposite 80 degree position and drag the other side of the blade in the same manner. This is a time-saver move for me. Repeat this motion with some pressure until the chipout is about 70% gone. Only 70%.

At this point you then tape the spine with one or two layers of tape [ your preference on the number of layers ] and then hone with a normal honing stroke until the chipout is gone and the bevel is about set. Because you bredadknifed 70% of the chipout and honed the other 30% away, the chipout will be gone and the bevel basically shaped at about the same time. Now you have gotten rid of the chipout and gotten a good bevel shape with a minimum loss of steel.


Many will disagree with my method but it has worked on numerous occasions for me. Results are everything. It only takes a few minutes to finish the bevel set on the 1000 Grit stone. The more you believe in what you are doing, the better chance it has to work for you.
 
Since you're honing with tape anyway, what benefit do you gain by not simply breadknifing the chip out completely? You'll see the same change in geometry since you're putting no wear on the spine in either method and are having to push back the edge the same amount.
 
By breadknifing 100% you would then have to set the bevel on a squared edge and lose more steel in the process. The goal is minimum loss of blade width.
 
Beveling an undamaged but unformed edge shouldn't move the edge back any. You're turning a squared off edge into an angled edge by grinding at exactly the angle you're going to establish. If you move the edge back at all, you simply continued on your low grit hone after the bevel was established. Now you could argue this is unavoidable to some degree, but really the amount of material this mistake should cost you would be completely insignificant unless you made a severe misjudgement of when your bevel was established. The advantage of breadknifing, more than the speed, is that it lets you set the blade depth you want quite accurately, if for instance you're repairing a razor with a too-shallow angle from an overzealous restorer taking out spine pitting.
 
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By breadknifing 100% you would then have to set the bevel on a squared edge and lose more steel in the process. The goal is minimum loss of blade width.

Would not make a difference.

If the chip is 3mm back from the edge, the new clean edge will be 3mm back from the existing edge.
You can breadknife it, then set the new bevel without moving the new edge back an appreciable amount, or you can simply work it for a longer time on the coarse stone to hone the chip out.
 
Allllrighty. Lets get started here.

Fast Eddie (relevant username!) - I really cant work out why you use this technique, except for the fact its maybe a little quicker.. I dont accept that as a valid reason - if you want fast use a cartridge, we use straights because we accept that we need to trade a little time for the quality of the shave. The fact that you expect it to upset 90% of the user-base means that there probably is something inherently wrong with whats happening here.

Please excuse the awful diagram.. art is definitely not my strong point.. but it should help illustrate what I mean.

We have 4 razors here, with the red lines measuring the angle at the edge:

$breadknifingwithtape.jpg

A) Regular razor, with the factory set angle of spine to bevel
B) Regular razor that has had a chip removed. As you can see the angle remains the same because both the spine and the edge wear together.
C) Razor that has been breadknifed. The angle is more obtuse because the spine hasn't had any metal removed when the edge has.
D) Razor that has been breadknifed AND had tape used. Even more obtuse angle because not only was the spine not worn down, but there has been material added here.

What this tells me is that I don't want to shave with D. That angle is getting waaaay to obtuse, and the razor is no longer as comfortable as it can be.

Sure, you might get a good shave out of it, power to ya. But there is a solid chance that you would get a better shave at the correct angle. There is a reason that razors have spines and knives don't.. there is a specific reason we use an angle within a couple of degrees of 17.. because that's the best angle for shaving.

Long story short: Your razors, do as you please. But any of the guys that are new to honing that read this, just think about whats happening to the edge here... and don't do it.
 
It seems that my thread flushed out some interesting and valid thoughts on the matter. Any new guys who read this thread will have plenty of thought provoking reference material to help them make the right decision for their blades. Thanks for the illustrative and informative posts.
 
Allllrighty. Lets get started here.

Fast Eddie (relevant username!) - I really cant work out why you use this technique, except for the fact its maybe a little quicker.. I dont accept that as a valid reason - if you want fast use a cartridge, we use straights because we accept that we need to trade a little time for the quality of the shave. The fact that you expect it to upset 90% of the user-base means that there probably is something inherently wrong with whats happening here.

Please excuse the awful diagram.. art is definitely not my strong point.. but it should help illustrate what I mean.

We have 4 razors here, with the red lines measuring the angle at the edge:

View attachment 391902

A) Regular razor, with the factory set angle of spine to bevel
B) Regular razor that has had a chip removed. As you can see the angle remains the same because both the spine and the edge wear together.
C) Razor that has been breadknifed. The angle is more obtuse because the spine hasn't had any metal removed when the edge has.
D) Razor that has been breadknifed AND had tape used. Even more obtuse angle because not only was the spine not worn down, but there has been material added here.

What this tells me is that I don't want to shave with D. That angle is getting waaaay to obtuse, and the razor is no longer as comfortable as it can be.

Sure, you might get a good shave out of it, power to ya. But there is a solid chance that you would get a better shave at the correct angle. There is a reason that razors have spines and knives don't.. there is a specific reason we use an angle within a couple of degrees of 17.. because that's the best angle for shaving.

Long story short: Your razors, do as you please. But any of the guys that are new to honing that read this, just think about whats happening to the edge here... and don't do it.
There is another thread going on about smoothness. Look it over. Feather blades use either a 19 or 24-25 degree angle. Straights tend to be around 15 degrees.
 
Straights seem to run run 15-19deg, the majority around 17.
Feather DEs have, I think - 3 bevels, the final is 20+, the primary is around 17.
Someplace there's pix of them.
FWIW - my straight edges last way longer than any Feather blade.
I believe simple de blades were found to be in the 17deg zone.
 
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There is another thread going on about smoothness. Look it over. Feather blades use either a 19 or 24-25 degree angle. Straights tend to be around 15 degrees.

De blades have multiple bevels. Are Teflon coated. Are designed to last a week at most. Are mass produced with lower quality metal etc etc.

i don't see it as being entirely analogous.

And if straights tend to be around 15 degrees that doesn't change anything I'm saying, >15 remains getting too obtuse
 
Nice drawing and explanation by mdunn. Said it better than I can.

I used to breadknife a lot. I did it in similar fashion, except without the tape. I actually would start by dragging the blade spine first at a 45 degree angle and gradually stand the razor up on its edge, or nearly so, actually. Yeah 80 degrees is about right. That stops a lot of chattering and chipping.

Once I started thinking about what I was doing, I stopped breadknifing. If I take steel from the edge, I want to take steel from the spine as well. The spine can always be sanded round-ish again.

A Gold Dollar #66 right out of the box and off the hones, with no modifications, is around 19 degrees. It will give an unspectacular, but very gentle shave, and you will seldom cut yourself even as a newbie with it. But it is like Daddy's old Buick compared to the same razor slimmed down to about 16-1/4 degrees to give a more Corvette type shave. I have shaved with a few ebay rescues that were about 14-1/2 degrees and they require a lot of attention to the shave at that angle. BTW, if a blade will even support such a fine edge that is a testament to the quality of the steel. The sweet spot is usually around 16-1/2 to 17 degrees for most hollowground razors.

You can certainly ignore this important detail, and usually get satisfactory results. But why not go for the best that you can do? There is a middle ground. Without measuring and calculating and compensating, you can still at least keep the bevel angle more or less as you find it, by simply honing the razor without tape and without breadknifing. The spine and the edge are meant to wear more or less in proportion, which is what sets the bevel angle in the first place.

But your razor. Do as you like.
 
My biggest razor is a nearly NOS 9/8th hollow (since I sold my 9/8 wedge) that has a grind angle of 14.1 degrees. Shaves like a champ. Measured a handful of razors I use regularly and got as high as a hair over 16 degrees (a Puma that looks FAT spined compared to most of what I own). Grabbed a fully NOS, never saw a hone 6/8" hollow with the bright and shiny steel typical of the higher/faster production mid20th century years (imho a bit poorer quality steel than some other razors I've got). 16 degree's on the dot. I went through a dozen straights and only one broke 17 degrees (17.5*, noticeably the worst shaver of the ones I tested), though a degree or so off could be blamed on my eyes. My GD (bought as an 800, but maybe a 200, they aren't stamped) is 15.95* with virtually no wear on it.

Now the puma's a very smooth shaver... but so's the 9/8th. Honestly, the finish has worlds more to do with that then I could ever give grind angle's credit for.

edit: On a lark, grabbed a razor I actually put in the junk drawer solely for being a subpar shaver. 17.2* angle.

And again: Another binned razor for subpar shaves. 17.96* angle.

This is actually working out to be more reliable than I'd ever expect.
 
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see! i'm not making this stuff up!

Although based on your observations it seems im mistaken with 17* as the angle to shoot for - maybe that's to be considered the maximum?
 
Again, I wouldn't be at all surprised if I'm off by up to a degree from lining measurements up. But I'd certainly not want a razor anywhere close to 25* or even 20*. I went for one more "binned" razor I've got, and it was 16.4*, but the steel was in very rough shape on that one, so I wouldn't rush to blame the shaves on the angle with it. If I come across a 17*+ that I like using, I'll post it.

edit: Actually, my most used razor for the past 4 yrs and one of my smoothest shavers will get measured now. :: 16.07*
NOS version of that exact razor I display (never honed after factory job): 15.52*
8/8 nearly NOS I picked up for a song a few weeks ago... good shaver: 13.93*

I'm actually surprised how much thinner the grinds on the deeper razors have turned out to be (2 of my 3 thinnest grinds are 1"+), I was expecting the opposite.
 
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Again, I wouldn't be at all surprised if I'm off by up to a degree from lining measurements up. But I'd certainly not want a razor anywhere close to 25* or even 20*.

Agreed. And if a razor is already in the high 17*s, then breadkniving (even without tape) could push it up towards being worse than it could be.
 
All that anyone has to do is BK a wedge, hone it, and check the angle.
If it's up at 22+º then shave with it. Then - take down the spine and rework it to 17-ishº, hone, shave.

If you don't see a monster difference in the before/after - then you haven't been shaving long enough.
'Cause I can tell you it's like night/day to me.
 
Can one of you post some pics of a razor with a 22 degree angle that doesn't shave well? I want to see what it looks like.
 
So, if your sitting with an overworked spine, breadknifing is a pretty sleek way of getting the bladewear to catch up to the thinned out spine. In any other scenario, you are just fattening up an otherwize perfect racehorse.
 
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