Taping the EDGE

Many folks have thought that bread-knifing was a "taboo" subject so here is another I'm guessing.

Taping the edge.

as we all know the a steep angle form edge to sine gives a more durable edge but not always a very good one.when it is too steep you might as well use your pocketknife.

from time to time i find myself, especially after "bread-knifing" that i need to thin the spine a bit to achieve an optimum shaving angle. Well this means "hone wear" but to preserve the remaining width of the blade i find that taping the edge works.

so my question for you all is have you ever tried it or are you all content wit ha steep angle that while durable does not cleave the hair as cleanly as it should.

anybody else try this or am i simply a heretic?

HERETIC!!! Some one get a stake...You there, get a rope...You... yeah you, get a torch, we're gonna burn this demon!!:roflmao:roflmao

Geez man - you are one sick puppy, do you know that? :D

I have taped the edge before, but only as protection when I am working on a blade. But what you say makes some sense I guess. I have never been in a position where I needed to worry about the spine width and angle, fortunately. But if I ever am I will remember this thread.

James.

A good burning yes, i see, but will that not endanger the temper of the blade?

Sounds perfectly reasonable to me.

What I haven't heard a definitive answer on is how exactly spine width is designed when making a razor. Do makers of razors design the spine width exactly proportional to blade width to produce a specific angle for the bevel? If so, wouldn't you expect the bevel angle of all razors of a general type to be very similar?

Let's assume all the above to be true. Do you think that, due to the large surface area of the spine that's in contact with the hone relative to the edge, that the edge will always wear faster than the spine decreases in width (with respect to the bevel angle)? If so, how far do you think that would be before you might want to adjust the spiine width?

well i better dig out the calipers and start measuring.:hmmm:

I only have 3 different razors to look at but all three have a sort of "edge" or taper to the spine where it would contact the hone. Are they all that way? That would also be consistent in that it would wear a bit faster than if it was a relative large flat area (although still no where as fast as the edge) and the bevel angle wouldn't change as fast...

from my experience the spine, edge and entire bevel should all lay on the hone and thus be thinned equally but i have razors that i tape and some that i have "bread-knifed" but in the end i wonder if these will eventually destroy the blade geometry.

Ok... I thought some more about that last bit. (and now my brain hurts and I'm disoriented and confused).

I was thinking about a single particle on a hone. It cuts a groove in the steel passed over it right? Now if you pass a 0.5 mm wide piece of steel over it, it should cut a 0.5 millimeter long groove across the entire width. If you pass a 1 mm wide piece of steel over it, it should cut a 1 mm long groove.

If a particle cuts a groove through the entire width passed over it, wouldn't it decrease the depth of that piece of steel the same amount regardless of the width? Anybody get what I'm trying to say? Anything to it?

So maybe it shouldn't matter that the spine is "thicker" where it contacts the hone than the edge. It should still decrease in thickness proportional to the edge decreasing in width?

(I think I've been up too long. I'm going to bed)

by thicker are you meaning how wide the wear area is? ( much like the bevel area) or actual thickness of the blade at the spine.

I'm referring to the thickness of the spine itself, which with proper honing will wear away symmetrically wot the edge thus in theory maintaining the angle throughout the life of the blade.

but my question was does anybody else worry about this and what sort of angle is ideal?

IIRC there already was a test done on this some time ago, and the angle lies anywhere from 9 degrees to 18 degrees which means that either very, very, substantial blade wear or spine wear would be possible before actual blade geometry would come into effect.... In other words the usable part of the blade would be gone before this would ever make a difference... looking at some of the extreme blade wear on some of the E-bay "treasures" out there pretty much proves this also, as the blades were worn to almost nothing and the razors were obviously still being used.....

I will agree to meet anybody here in 100 years same time same thread and we can compare blade -vs- spine angles :D

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Originally Posted by gssixgun

IIRC there already was a test done on this some time ago, and the angle lies anywhere from 9 degrees to 18 degrees which means that either very, very, substantial blade wear or spine wear would be possible before actual blade geometry would come into effect.... In other words the usable part of the blade would be gone before this would ever make a difference... looking at some of the extreme blade wear on some of the E-bay "treasures" out there pretty much proves this also, as the blades were worn to almost nothing and the razors were obviously still being used.....

I will agree to meet anybody here in 100 years same time same thread and we can compare blade -vs- spine angles :D

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9 to 18 degrees... sort of like the epa... 9000mpg highway / 8mpg city you mileage may vary...

so nobody cares to advance the theory that a blade with a 9 degree angle will cleave the hair easier than say the 18 degree?

so keep the spine pristine and don't worry about the angle?

also i know that if the blade has been well maintained this will not likely be an issue... but for restoration blades is it a concern?

Jim, perhaps you'd get a better response if you post this in the forge - I suspect that people like Mike Blue, Josh, LR Harner, etc., will have a good idea of blade geometry and specifically how thick their spine has to be relative to the width of the razor. I would suspect that people who make razors have read up on this or experiemented...

Just a though :shrug:

Mark

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Originally Posted by Milton Man

Jim, perhaps you'd get a better response if you post this in the forge - I suspect that people like Mike Blue, Josh, LR Harner, etc., will have a good idea of blade geometry and specifically how thick their spine has to be relative to the width of the razor. I would suspect that people who make razors have read up on this or experiemented...

Just a though :shrug:

Mark

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Mark,
i thought about that but then carefully read the stickies and asked in the chat where the best place to place this was :)
i had thought the forge as well but since i was not making a blade or truly grinding it ... we came to the conclusion that it was a honing technique... besides i did not want a "timeout" for posting in the wrong area.:o

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Originally Posted by OLD_SCHOOL

I can't help but wonder if you started this thread after reading my post here. :hmmm:

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Nope i had stopped reading that thread awhile ago... sorry. I just read it all and i will still use this method i think... although i am less committed to taping the spine then i once was.

... so what happens when you do it? Do you just end with a used up razor with an ugly flat, or do you reshape the whole razor to make everything "fit"?

I think the width and the angle are both important factors in getting a comfortable shave. Especially from a full hollow ground razor.

You should look at the shape of the blade, the curvature by looking from the front rather than the sides of the razor. Its thickest at the spine and then it tapers to the edge. As you remove the thinnest part of the blade, the flex of the blade reduces and for me this reduces the comfort of the shave. Its common sense.

The ratio of thin versus thick seems to stay in proportion for whatever size the original blade is.

So if you take a 6/8" razor and reduce the edge by 1/6" you physically will get a blade that measures 5/8".

But don't be fooled that it will feel or shave the same as a an original 5/8" razor. It won't.

As for the angle, ofcourse it matters. The initial angle is set by holding the blade flat down on a spinning hone. The hone looks like a potters spinning wheel. The hone lays a flat bevel on the spine that is vertically in line with the bevel made on the edge at the same time. I believe you get the best shaves from a razor just so long as you keep this geometry intact. Breadknifing the edge, or taping the blade or the spine distorts the realtionship between the spine bevel and the edge bevel. There are reasons to do this if you are repairing a badly worn or damaged razor. Some argue that with razors with fancy spines or gold embossed spines, that tape protects the ornamentation . Some use tape to hone a secondary bevel to gain some extra smoothness and sharpness out of the edge. But changing the original geometry is in my opinion not a good idea and for me at least, once you have honed a 1/16" off the blade, the comfort and the feel of the razor is changed significantly from the original state.

Some forum members argue that just so long as the blade gives a good comfortable shave, there is no problem. I don't disagree with them. I also don't care if people use tape. I just think you should know that such a blade will feel different to a new blade with all the angles and width and tapers correctly in place.

I like to know what I am buying when I purchase a second hand razor. I like to know the history so I can determine how it might feel and in this respect, width and geometry matters.

Again I have to somewhat agree with the English-man :p
But would state it a different way... An older used razor feels different than a Brand New / NOS Razor.... Ummmmmm Yeah we know :D:D:D

But most of us don't want to toss the razors that have 1/8 or more blade wear at this moment in time.... so we try to keep them shaving....

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Originally Posted by gssixgun

Again I have to somewhat agree with the English-man :p
But would state it a different way... An older used razor feels different than a Brand New / NOS Razor.... Ummmmmm Yeah we know :D:D:D

But most of us don't want to toss the razors that have 1/8 or more blade wear at this moment in time.... so we try to keep them shaving....

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Not true with a wedge right? Maybe only with full hollows?

Hmmmmm I would think that it would not matter really, despite the blade contour as you move toward the spine, you are getting into thicker and thicker metal "the Belly of the Blade" so that would be changing the "feel"
But on the reverse side of that it seems that wedges / near wedges wear slower too :shrug:

English has pretty much summed up my belief, the edge is different and stiffer once a significant part of the blade is honed away. 1/16" on a 5/8 blade is 10% while it will be different it will merely shave like a less hollow ground razor... for folks using the half and quarter hollows they will probably never notice the difference but those who use very hollow ground razors the blade flex and comfort is degraded.

yes honing without taping the spine will in time lead to wide flat spots of hone wear on the spine but the shave quality will only slowly degrade as far as i can tell.

my contention is that there is truly an optimum angle based on the type of grind and blade width.


Glen... the only taping thread i can remember was all about how much/ if taping effects the quality of the shaving edge as in how much it might change the angle at the apex.

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Originally Posted by syslight

yes honing without taping the spine will in time lead to wide flat spots of hone wear on the spine but the shave quality will only slowly degrade as far as i can tell.

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That's what I was ruminating about earlier. Even if the hone wear spots on the spine get wider (and flatter) the spine should still decrease in width at the same rate it did when the hone wear spots were thinner (and less flat).

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Originally Posted by Quick

That's what I was ruminating about earlier. Even if the hone wear spots on the spine get wider (and flatter) the spine should still decrease in width at the same rate it did when the hone wear spots were thinner (and less flat).

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If I were to come across a razor that had that had uneven wear on the spine I would probably pass on it unless it was a make or model I really wanted badly. In that case I would probably send it out for a regrind rather then trying to restore it myself. Edges are one thing but spines are for me a horse of a different color.

One more thing that comes to mind is my father telling me years ago that the further up you get into the blade of a pocket knife the temper changes. When you get a pocket knife that is honed to the point where the edge is now up into the belly of the blade the temper is not as hard as it was in the original edge.

I am not sure if this is correct but it made sense to me and if it is correct that means that the spine may be softer then the metal at the edge and wear at a faster rate if not taped. More knowledgeable members on the mysteries of temper and metallurgy will no doubt correct me if I am wrong.

There's really no way to generalize about how much of the edge can be honed away before the steel qualities begin to change (from regions of varying hardness).

But there is a key difference between straight razors and pocketknives that may be relevant; razors are intended to be honed laying flat, so the spine ought to be a similar hardness to the edge to minimize unpredictable hone wear, whereas pocketknives are only honed on the cutting edge, so the spine may be tempered to a lower hardness to facilitate a "tougher" blade by reducing the amount of brittle Martensite.

So for all intents and purposes a straight razor ought to have a uniform (or very close to uniform) range of hardness, a range that probably doesn't go out of the bounds of usability.

As for the test results of 9 to 18 degree bevel angle acceptability, that may or may not have been an experiment I did, but my results were more like ~12 to ~22 degrees. I made a series of razors that had bevel angles in that range and gave them all edges from the same progression of hones to see how the angle affected shave quality. I even took the ones with very acute angles and honed them with multiple layers of tape to identify the angle that was too large for the given piece of steel. The results were in the above stated range, with very little detectable difference if the angle was kept reasonably close to its original condition. The biggest difference was in the initial quality of the steel.

So while its good practice to keep a razors geometry as close to original as possible, the razor's performance isn't going to be adversely affected by an extra degree or two of bevel angle and may be perfectly fine with a few extra degrees more.

To each his own, I suppose.

Good point regarding the difference between pocket knives and razors. Thanks for the blade angle tests too.

OK! for a relative feel

My 5/8 Dovo Micarta has (roughly) the following dimensions:
15.875 mm from spine (where it contacts layed flat) to edge
5 mm spine width

That's going to give me an approximate bevel angle of 18.12*

If I were to tape the spine and lose 1/8" of blade, the bevel angle would go to 22.71*
If I were to tape the edge and lose 1 mm of spine width the bevel angle would go to 14.48*

So would it be that the steeper the bevel becomes the closer the spine should be to the face?

I feel sorry for the early retirement of a razor by abuse and neglect, but not guilty enough to feel the need to resurrect one. I think they could be made to feel useful as box cutters

Well, yes. But I think the assumption is that the spine wears and gets thinner as the edge wears and gets closer to the spine. So the bevel angle is maintained closer to what it started as the razor wears.

But from the observations in the above posts maybe it's not an immediate crisis if you always tape the spine as opposed to wearing the spine down as the blade width decreases.

We still haven't heard how exactly blade makers design the geometry. Does Dovo manufacture their Micarta razor to have exactly an 18.2* edge angle? Or would anything between 12* and 21* pass QA? (primarily determined by spine width). Do they even consider how the geometry changes as the razor wears? If you asked Dovo what they thought about taping the spine as you maintain your razor for the next 50 years, would they say "absolutely not!" or would they say "eh... it doesn't really matter"?

Fwiw, blade angles greater than ~22 degrees may be perfectly fine, depending on the individual qualities of the razor's steel, I just know that 22 deg. is still a very usable angle for all intents and purposes.

In other words, don't throw away a razor just because it's bevel angle is greater than some number you've heard reported, test it for shave worthiness first.

Here here Russel, after all, isn't the shave test the ultimate deciding factor?

I'm sure there are optimum angles and all, I mean clearly tests have been done to prove such. But really shouldn't it all come down to how well it shaves?

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Originally Posted by JCitron

Here here Russel, after all, isn't the shave test the ultimate deciding factor?

I'm sure there are optimum angles and all, I mean clearly tests have been done to prove such. But really shouldn't it all come down to how well it shaves?

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I think that's what Russel said. Don't throw it out if it shaves well just because the angle is out of the "norm". Russel's observations were that the bevel angles from the mfgs fall in a relatively broad range. Broad enough that a degree or two of change isn't that significant. Another interesting implicationthat Russel made was that an optimum angle is corrrelated to the characteristics of the steel.

Surely personal shave angle would be a factor as well. Someone who shaves with a greater angle than someone else would get different results with the same edge angle. If you really wanted to get precise I suppose you could optimize the bevel angle to not only the steel but to the individual shaver as well :). LOL, that could be the next SRP service. Personal razor fitting, right down to the optimum edge angle for you.

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Originally Posted by Quick

I think that's what Russel said. ...

...Surely personal shave angle would be a factor as well. ...

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It was, I was just agreeing with him. But now you've pushed me to try to figure out what the optimum angle of the blade should be relative to my face given each razors unique bevel angle. Damn! Just when I thought I was starting to get a hold of everything. :rofl2:

Quick, I understand what you're really looking for is a chart or some reference to the ratio of blade width to spine thickness and what angles the resulting ratios create. I swear within the last year I saw someone link to something like that. While Russel has shown with his great experiment that a range of angles can serve a razor well, blade width to spine thickness ratio can't be a completely arbitrary choice and expect that the resulting blade, if it looks like a razor will shave well. I wouldn't want to shave with an 8/8 1/16" thick spine razor nor would I want to shave with a 3/8 1/4" thick spine razor!:)

Chris L

Chris,

I think you're onto something. Each razor should have its bevel carefully measured, which factor then will be entered into a carefully empirically derived equation which will yield the exact angle at which the razor must be held to the face for optimal shaving. Any deviation from this proper angle will then automatically delete any requests for help from the august panel here in attendance. All calls for help must be prefaced with the dangle angle, which will be scrupulously noted and assiduously compared to the data carefully filed and held at angle central.

Yes, yes, an answer to yet another of life's nagging problems. :rock:

:rofl2:

Exactly, Bruce. And...precisely! Finally, someone who understands me!

Chris L

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Originally Posted by Chris L

Quick, I understand what you're really looking for is a chart or some reference to the ratio of blade width to spine thickness and what angles the resulting ratios create. I swear within the last year I saw someone link to something like that. While Russel has shown with his great experiment that a range of angles can serve a razor well, blade width to spine thickness ratio can't be a completely arbitrary choice and expect that the resulting blade, if it looks like a razor will shave well. I wouldn't want to shave with an 8/8 1/16" thick spine razor nor would I want to shave with a 3/8 1/4" thick spine razor

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Ummm, no. No need for a chart. It's just triangle geometry. You have 3 sides and 3 angles. Given any 3 of those values you can solve for the other 3. If you want to know the bevel angle produced by your current blade width and spine thickness you can use SSS. If you want to know what spine width you need to produce a specific bevel angle you would use SSA to solve for the spine width (or, since 2 sides are equal, how much to take off your blade width :)).

I had interpreted Russel's findings to be that most razors seem to be manufactured to produce a bevel angle within 12* and 22*. Further, that acceptable shaves are realized within that range. I think Russel also implied that when he went outside of that range that it was less possible to achieve an acceptable shave.

So that pretty much answered the question. 12* to 22* is, relatively, a large range.

I used my 5/8 Dovo Micarta as an example. It starts out with a 5/8" wide blade and a 5 mm thick spine which results in a 18.1* bevel. If one always taped the spine, the bevel angle wouldn't go out of this "acceptable" range until you had removed a full 1/8" of blade width from the edge (1/5th of the blade would have to be removed). Conversly if the spine width was lessened by a full 1 mm (without touching the edge of the blade) you would still be well within this range.

Conclusion: given that you start well within the acceptable bevel angle range, it would take a LOT of honing with disproportional wear to have a significant effect on shavability. ==> factoring the change in bevel angle over time, into the decision to tape or not to tape is probably not a consideration ;)

Still useful information if one has a razor with a bevel angle close to the limits. Also useful if you might be trying to decide if a badly disproportional razor is worth restoring or not.

Now... (haha) since many are going to any lengths searching for the holy shaving grail... I was postulating that matching the bevel angle to your preferred shaving angle might bring significant results. I'm guessing that those who shave with a greater angle (spine away from skin) would do much better with a greater bevel angle. This would keep the surface of the bevel much flatter on the skin. Those with less of a shave angle would probably do better with less of a bevel angle. In fact, I'm guessing you would want the bevel angle to be the same as your shave angle (or visa versa).

Might explain why people are much more partial to some of their razors over others?

You're talking to a bunch of guys who think taking an extremely sharp razor to their throats is a good guy. Heretics are as welcome here as lunatics. : )

If you want to change your bevel by taping the spine, go ahead. Lots of guys do this for various reasons ranging from protecting the spine to putting a secondary bevel on the razor. This should not be a verboten topic and, as a lifelong honer, let me instead ENCOURAGE you to experiment with new techniques.

Breadknifing is an old technique. Read about it on my "Honing How To" page in an excerpt from a book written in 1908 by a Cornell professor of cellular biology. The excerpt is about honing microtomes which he says should be much sharper than razors . . . .

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Originally Posted by Howard

You're talking to a bunch of guys who think taking an extremely sharp razor to their throats is a good guy. Heretics are as welcome here as lunatics. : )

If you want to change your bevel by taping the spine, go ahead. Lots of guys do this for various reasons ranging from protecting the spine to putting a secondary bevel on the razor. This should not be a verboten topic and, as a lifelong honer, let me instead ENCOURAGE you to experiment with new techniques.

Breadknifing is an old technique. Read about it on my "Honing How To" page in an excerpt from a book written in 1908 by a Cornell professor of cellular biology. The excerpt is about honing microtomes which he says should be much sharper than razors . . . .

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Was his book applauded? or was he just deemed a lunatic. :)

Howard, as a lifelong honer give us your thoughts on bevel angle (generally speaking).

* Is there a range of bevel angles, outside of which an acceptable shave is unlikely?
* Do razor manufacturers design their blades for a particular bevel angle determined by spine thickness?
* Is there a different "optimal" bevel angle for different types of steel?
* Do you take the resulting bevel angle into consideration when deciding if a disproportional razor is restorable?
* Would matching a bevel angle to shave angle make a noticeable difference?

(I make a distinction between bevel angle and "sharpness")

Here's what I'm wondering about with shave angle.
Let's say you end up with a 15* bevel for whatever reason. Are you likely to get the best shave with a 15* shave angle?

*note: I think the graphic artist I commissioned was under the influence so it's not exactly to scale...
http://i97.photobucket.com/albums/l2...Shaveangle.jpg

Those are great drawings! I would think that the middle 15/15 would be the best shave, with the last resulting in cuts and aggravation and the first leaving stubble.

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so nobody cares to advance the theory that a blade with a 9 degree angle will cleave the hair easier than say the 18 degree?

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although I would think the lesser angle will be most sharp:hmmm:
It may also have to do with the differences in facial hair between different people, some with thick hair, some fair and fine, and the fact that angle can be adjusted by a tip of the hand holding the razor, making slight angles changes pointless, somehow the human hand can tell the right angle by just feeling how the blade is cutting and adjusting "on the fly"! :thinking::D
each one will have that perfect angle, just got to find it!

My observations disagree with the ones expressed so far: I have 3 different razors: one 20 degrees, one 18 degrees, and one 15 degrees. The 15 clearly shaves better than the 18 (for both thick and fine hair), which in turns shaves better than the 20. The final result between the 3 razors is the same but what I mean is that the 15 shaves more effortlessly. BTW, the 15 degree razor in question is a 6/8 Beau Brummel with natural hone wear, it was 17 degrees when new.

So far the more extreme the angle, the smoother the shave. Next, I will try a 13 degree Dubl Duck. This is about as extreme an angle as you can go probably.