bevel width

Hi,
What widths of cutting edge would be proper for full wedge, 1/4 hollow, 1/2 hollow, full hollow razors? Let's say blade widths are a, b, c, d. I believe it's non-linearly proportional to blade width but cannot formulate it so maybe I'm wrong.

Edit 1:
I'm assuming blade thickness varies with width so as to keep the bevel angle constant.

Let me put a crude classification here:

Hollowness:
full wedge:A
1/4 hollow:B
1/2 hollow:C
full hollow: D

blade width:
15 mm(or 5/8) = a
18 mm (or 6/8)= b
20 mm (or 7/8) =c
25 mm (8/8) = d

So what edge width should a "A-b" razor have? What about others?

Edit 2:
This makes 4x4=16 razors. Pick any combination you are familiar with and tell which bevel width you prefer, that will also help.

Thanks.

Quote:

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Originally Posted by ferroburak

Hi,
What widths of cutting edge would be proper for full wedge, 1/4 hollow, 1/2 hollow, full hollow razors? Let's say blade widths are a, b, c, d. I believe it's non-linearly proportional to blade width but cannot formulate it so maybe I'm wrong.
Thanks.

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I may misunderstand your question .
cutting edge has nothing to do with grind of the blade?

I'm sorry, I don't think I quite understand what you are asking here.

Are you talking about bevel widths in relation to grind and blade widths?

If so, then the more hollow the blade is, the narrower the bevel ,and the more wedge-like it is, the wider it becomes. Given the same spine-size. A full wedge has the whole blade side as a bevel.
Then the blade widths works the other way, given the spine is of a constant size.
The wider the spine is, the narrower the bevel becomes. Naturally not so on the true wedge.

Or something to that effect:)

Quote:

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Originally Posted by hi_bud_gl

I may misunderstand your question .
cutting edge has nothing to do with grind of the blade?

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I think they counter act(not sure this is the correct word). The more hollow the blade narrower the edge width should be so that bevel flexes in desired amounts during use.

Quote:

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Originally Posted by Birnando

I'm sorry, I don't think I quite understand what you are asking here.

Are you talking about bevel widths in relation to grind and blade widths?

If so, then the more hollow the blade is, the narrower the bevel ,and the more wedge-like it is, the wider it becomes. Given the same spine-size. A full wedge has the whole blade side as a bevel.



Then the blade widths works the other way, given the spine is of a constant size.
The wider the spine is, the narrower the bevel becomes. Naturally not so on the true wedge.

Or something to that effect:)

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I agree with the first part but couldn't understand the second part.

there is differences between bevel and edge.
Edge is cutting edge which cuts the hairs.
Bevel has nothing to do with cutting .
i hope i was clear.

Ok let me put a crude classification here:

Hollowness:
full wedge:A
1/4 hollow:B
1/2 hollow:C
full hollow: D

blade width:
15 mm(or 5/8) = a
18 mm (or 6/8)= b
20 mm (or 7/8) =c
25 mm (8/8) = d

So what edge width should a "A-b" razor have? What about others?

Quote:

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Originally Posted by ferroburak

I agree with the first part but couldn't understand the second part.

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What I mean is, given a constant spine width, the bigger the blade is, the wider the bevel becomes. Bigger blades in this context meaning wider. E.g. a 4/8 vs 8/8, the bevel on the 8/8 will be wider than the one on the 4/8, if the spine width and grind is constant.

Quote:

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Originally Posted by ferroburak

I think they counter act(not sure this is the correct word). The more hollow the blade narrower the edge

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Sorry it is not.

Quote:

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width should be so that bevel flexes in desired amounts during use.

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Are you trying to ask width of the bevel? or the blade?

Quote:

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Originally Posted by hi_bud_gl

Sorry it is not.

Are you trying to ask width of the bevel? or the blade?

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Hi,
I mean bevel, I don't think bevel width can be chosen arbitrarily so my question came from it.

Quote:

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Originally Posted by ferroburak

Ok let me put a crude classification here:

Hollowness:
full wedge:A
1/4 hollow:B
1/2 hollow:C
full hollow: D

blade width:
15 mm(or 5/8) = a
18 mm (or 6/8)= b
20 mm (or 7/8) =c
25 mm (8/8) = d

So what edge width should a "A-b" razor have? What about others?

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I think this is quite impossible to set figures to.
The reason I feel that way is that you are missing a key element here, and that is spine width. Geometrically that will be one of the determening factors.
As an excample I have different razors in the same width and grind with very different bevel widths due to varying spine widths.

Quote:

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Originally Posted by Birnando

What I mean is, given a constant spine width, the bigger the blade is, the wider the bevel becomes. Bigger blades in this context meaning wider. E.g. a 4/8 vs 8/8, the bevel on the 8/8 will be wider than the one on the 4/8, if the spine width and grind is constant.

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Hi,

Ok I see now. But a 8/8 wouldn't have twice the width of a 4/8.

How can I formulate it?

Quote:

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Originally Posted by Birnando

I think this is quite impossible to set figures to.
The reason I feel that way is that you are missing a key element here, and that is spine width.


Geometrically that will be one of the determening factors.
As an excample I have different razors in the same width and grind with very different bevel widths due to varying spine widths.

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I assumed blade spine thickness varies so as to keep the bevel angle at a constant value, say 17 degrees.

Hello,

assuming your talking about the width of the bevel that creates the cutting edge... only in the wedge does the grind matter, in a true wedge the bevel wedge would be the entire width of the blade, unless you use tape. For other grinds the bevel width mostly depends on spine thickness and how wide the blade is, which determines how much metal would be removed to create the "cutting bevel". the grind does make some small difference but only noticeable when you get into the "wedgies".

Or is this question about what width of blade corresponds with the grind?, for example 4/8th for wedge, 5/8 for quarter hollow, 6/8 for 1/2 hollow? I don't think that matters.

there are 3 variables in your question so i'm not sure which one to base my answer on,
I would love to know what your thinking so please restate your question?

Quote:

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Originally Posted by ferroburak

No,

I assume that blade spine thickness varies so as to keep the bevel angle at a constant value.

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In my experience, your assumption here would be wrong.
There are slight differences to the angle of the bevel.

As an example, add a layer of tape, and what you get is a narrower bevel and a more acute angle on it.
Minute difference for sure, but it is there, and that's how it is with different razor models as well. No absolute angle they all use as far as I know.

I hope I am understanding you correctly here, not trying to argue at all, just trying to help, and to understand correctly.

Quote:

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Originally Posted by Birnando

In my experience, your assumption here would be wrong.
There are slight differences to the angle of the bevel.

As an example, add a layer of tape, and what you get is a narrower bevel and a more acute angle on it.
Minute difference for sure, but it is there, and that's how it is with different razor models as well. No absolute angle they all use as far as I know.

I hope I am understanding you correctly here, not trying to argue at all, just trying to help, and to understand correctly.

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Hi,
The angle is around 15 degrees so let's keep it constant in order to simplify/model the problem. Thanks for the help.

Ok i think i am getting slowly what you are trying to ask.
i think you are trying to find out the best spine to edge angle.
which is between 16-20 degree and if am not mistaken 16,5 is the best.
Now putting in bevel in to conversation will confuse a lot of us at least me.
Bevel could be wider or narrow has nothing to do with sharpness of the cutting edge.
hope i am helpful.

Quote:

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Originally Posted by ferroburak

I assumed blade spine thickness varies so as to keep the bevel angle at a constant value, say 17 degrees.

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Yes this is correct.
wider the blade thicker the spine in simple words?
as you hone your wear down spine and the edge same time.
angle stays same.

Quote:

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Originally Posted by 111Nathaniel

Hello,

assuming your talking about the width of the bevel that creates the cutting edge... only in the wedge does the grind matter, in a true wedge the bevel wedge would be the entire width of the blade, unless you use tape. For other grinds the bevel width mostly depends on spine thickness and how wide the blade is, which determines how much metal would be removed to create the "cutting bevel". the grind does make some small difference but only noticeable when you get into the "wedgies".

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You got my question correct but I disagree that the difference is small.

I'm well aware that my question is hard to answer and also depends on steel type, shoulder type and personal preference. I nevertheless believe, if bevel width is in question, other parameters are insignificant compared to blade width-blade grind.

Maybe it would be best to start with my second question. Taking other variables constant, how wide a bevel would you put on a "A-b razor" as described in posts 1&7?

Thanks for the all help.

I got this calculator from someone else on the forum, don't know who or where now, but it might help you out...

http://www.coticule.be/wedges.html?f...alculation.xls

I need to learn more about this for custom straight razor making purposes.

The bevel angle should be around 17 degrees and it's determined by the ratio of the spine thickness to the width of the blade, it's simple geometry.
The width of the bevel depends on the bevel angle and the geometry near the edge i.e. the thickness of the blade and the grind, but from what I've seen simple circular hollowing is oversimplification of it, so you can't really have a single formula that fits all.
I can derive you the formula when it's a simple circular grind, it's just basic math, but I don't think it has any practical meaning unless you're talking about thick grinds only.

For razor making purposes all you need to do is determine how thick the stock has to be to achieve a proper angle for your width of blade.

I don't think it's anything more complicated than that, and the bevel does not even come into play, and the grind doesn't mean much either.

Let's take a full wedge, for example, and let's make the spine 1/8" and the blade 4/8" (or 1/2"). Based on that you can determine everything you need to using basic trigonometry. Split the blade in two, and you have two right angle triangles 1/16"x1/2"; calculate the hypotenuse, and then the angles. The shoulder angle is a direct calculation, and the edge angle is twice the result of your math.

If you take a full hollow, the calculations are the same. The only difference is that the bevel won't extend the whole side of the blade.

To make a razor from scratch, just assign your "bevel" an angle of somewhere between 16 and 18 degrees (someone mentioned 16.5 was ideal) and work out the geometry from there.

Good luck.

the thicker the blade ( like a wedge)the wider the width of the bevel now if you want a narrower width then tape the spine and the second part of the question is a full hollow razor bevel would be around 1/8 of an inch