Thread: Wider blade = finer edge?

While reading some of the posts on here about preferences, I realized why wider blades sometimes seem to give a smoother shave.... simple geometry.
If the spine is the same thickness, the wider blade is going to have a shallower angle on the hone.

Shallower angle equates to a thinner bevel and IME, thinner equals sharper.

Does this make sense, or am I way off?

Paul

I'm no expert on blade geometry but I believe that a thicker spine, relative to the width of the blade, leaves a steeper angle and a thinner bevel. OTOH, a wider bevel won't necessarily give less of a smooth shave, but I think it might be more fragile. I may be wrong, I was wrong once before.

I don't think one can say that wider is better or sharper as a general rule.
Most razors are designed to meet a specified angle on the bevel.
My experience is that the angle seems to be within a couple degrees regardless of how wide the blade is.
If it is made to shallow, the edge will simply not be tough enough to hold up during stropping and shaving.

Originally Posted by JimmyHAD

I'm no expert on blade geometry but I believe that a thicker spine, relative to the width of the blade, leaves a steeper angle and a thinner bevel. OTOH, a wider bevel won't necessarily give less of a smooth shave, but I think it might be more fragile. I may be wrong, I was wrong once before.

Jimmy, I believe you and I are using "thinner" in different context. I'm referring to the cross section view, and if I am interpeting your post correctly, you're referring to how "thin" is is when looking at it from the side of the blade.

Originally Posted by knitepoet

Jimmy, I believe you and I are using "thinner" in different context. I'm referring to the cross section view, and if I am interpeting your post correctly, you're referring to how "thin" is is when looking at it from the side of the blade.

I'm thinking of it both ways. If it is wider from the side it would be thinner in cross section and therefore more fragile. I'm thinking a narrower bevel seen from the side would have more steel in cross section. At the edge the bevel is so thin one way or the other it might not make a dimes worth of difference as far as durability goes. In my minds eye I was thinking of wedges anyway. Full hollows are a different kettle of fish.

Originally Posted by Birnando

I don't think one can say that wider is better or sharper as a general rule.
Most razors are designed to meet a specified angle on the bevel.
My experience is that the angle seems to be within a couple degrees regardless of how wide the blade is.
If it is made to shallow, the edge will simply not be tough enough to hold up during stropping and shaving.

That's why I specified "if the spine is the same thickness" (width)
It seems folks can change how well a blade is sharpened by adding one thickness of electrical tape along the spine. I haven't taken time to get an exact measurement of any, but IIRC some of what I've seen advertised was 0.03" (0.762mm)

It's all good Jimmy
I was mainly thinking "out loud" and figured there would be some folks who could correct my thinking

The answer is yes and no. As Jimmy & Birnando mentioned, a edge may be more fragile if at too shallow of an angle...then you get into the variables as to hardness of steel and so on. Even smoothness is quite a variable, what I may consider smooth shaving razor you may consider not so much.

If you will notice, the wider the blade like an 8/8, the wider the spine as to keep geometry right. A 4/8 razor typically has a rather narrow spine. Those old guys back in the day may not have known our "geometry", but they new what worked.

That last 1% of honing is what most people notice the most, which is from the finishing stone and final stropping before a shave.

Originally Posted by knitepoet

That's why I specified "if the spine is the same thickness" (width)
It seems folks can change how well a blade is sharpened by adding one thickness of electrical tape along the spine. I haven't taken time to get an exact measurement of any, but IIRC some of what I've seen advertised was 0.03" (0.762mm)

Adding that layer of tape doesn't have any significant effect on the bevel angle, especially as "normal angle" is a range. Also, wider blades have wider spines, so to get a spine on a wide blade to be the same width as the spine on a narrow blade, you'd have to grind down the spine on both sides.

I'm not sure what happens when the bevel angle becomes wider/larger than the optimal range, but if the angle gets too narrow/small, it has negative effects on the blade's ability to hold the edge. Less steel means less durability. I don't know if the first shave would be any better with a smaller angle, though.

Through a bunch of measuring by a few of our members here, we found that Razor bevel angles range from about 13 degrees to 23 degrees all of these razors were shaving and shaving well...
the average angle was 16 degrees and most razors fall between 15 and 17

One layer of 3M electrical tape on a 6/8 inch razor changes the bevel angle about .72 degrees so you can see that you would need multiple layers to really change an angle.. most people don't use multiple layers (over 3) as it creates other problems...

What you have heard is true there are different thickness of spine for different width of blades "When they were produced" bad honing over the last 200 or so years has changed many razor's geometry.,, Spine hardness vs edge hardness can also play a role...

All this combines to keep the edge shaving along with the steel itself...

In a perfect world the spine will wear equally along with the edge to keep the razor in sync,,, it ain't a perfect world out there in the used razor market often enough