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Would the Apex Width be the same on a Full Hollow as on a Wedge with both grinds having the same bevel angles?
I have to ask this question because the more i think on it the more complicated it is.
An extra hollow grind has to have a finer edge than a near wedge doesn't it? My reasoning is not based on maths but on my face telling me what i have felt over the years..
I would be interested in your thoughts..Thanks
Can get both types of grinds the same amount of sharp though the technique to get there is slightly different. The full hollows I have made are generally more flexible than most vintage full hollows and I experience similar shaving comfort and closeness between those and the 1/4 hollows I’ve made. As far as an apples to apples comparison I have control over every aspect of the build except for the steel content.
Now on to your thought exercise. I can’t see how, given equal parameters that the edge would be any different in profile or how narrow the apex is. I can get to my ideal edge much more easily on a full hollow than a wedge or similar grind. With the ability to flex the edge enough to clear more material behind the edge makes it easier to get your stones to hone all the way out to the edge. Though the idea is no different than changing the tape or adding a strip as you hit your finisher.
I think the biggest perception of difference in edges is most likely located in the hands of the end user.
Well that's an interesting observation! My thought is that if the spine were the same thickness on both a wedge and a full hollow, it would be the same due to the angle you would get on the hones. However there are always variables associated with this. Tape on the spine, person doing the honing, and personal preference in defining a finer edge based on comfort level on ones' face, etc.Quote:
Originally Posted by JOB15
I don't personally have a wedge so, I can't really give you a more refined answer. I only own hollow ground razors. But what I can tell you is that I look at the spine and see how much hone wear is on it and if it is consistent all the way across. If it is, I usually have a very good edge and lot's of comfort. The edge is fine, but not too fine as to where it folds.
However, I have noticed that when I have uneven hone wear on the spine, the edge is not as pristine and the comfort level drops slightly. I still get a great shave but notice little spots on face that aren't as smooth as the rest of my face.
I hone without tape until I get consistent hone wear along the spine. When that happens, I know the edge is consistent and produces the ultimate edge that is comfortable for my face. At that point, I use linen and leather to keep it in top condition.
I would think that a wedge would be the same, but again I don't have any wedges.
I'm having a hard time following what you are saying as an apex is the very point and has no width. I take it you mean bevel widths. An extra hollow ground razor should have a minuscule bevel width, almost nonexistent. By comparison the same size wedge blade with the same spine width should have a visibly wider bevel width but still not huge. You have to clear away more metal off the sides of a wedge blade to create an apex where the bevels meet than you do with an extra full hollow blade to get the same bevel angle.
Bob
No Bob, I mean Apex width.. Everything has a width if you zoom in close enough..Quote:
Originally Posted by BobH
I can now argue for both sides.. Technically the answer seems to be that the apex widths would be the same. However, a wedge has more mass and hollows do feel finer, i am told that is because they are more flexible ....but rigidity is due to mass..Even writing this i am having deeper thoughts.
The wedge bevel touches the hone at a lower level, would that not make for a wider apex..:gaah:
Apex width would be identical given the same angle and other properties beside the grinding. You're overthinking it imo, mass, flexibility, all that stuff is irrelevant to angle and incidentally apex width. It does affect how the shave feels but that's another matter. :P
This I'd go along with. The apex width would be the same regardless of grind given identical blade and spine widths as the bevel angle is the same. The only way the apex width would be different is if the bevels did not meet to form an apex in the first place as in an unset bevel.Quote:
Originally Posted by thp001
Bob
If you run your thumb nail down the bevel on an extra hollow you can see the bevel flex through the other side, that is the apex flexing also..
A wedge under the same test would not flex. Might that mean that the bevel & apex are thicker, stronger, wider..
Possibly :)
I can't see a apex having a different width. If its not perfect, its simply..... Dull. Hollow or wedge.
I feel a wedge, has a higher shaving angle, than hollows. I've noticed that if I shaved with a wedge like a hollow, the blade had a tendency to stick to my face. :shrug:
There's just less supporting material behind the edge bevel so you get that high flexibility although it isn't true that you don't get flex on a wedge.Quote:
Originally Posted by JOB15
When I make my own razors, most of which are wedges, they're ground down to an apex before setting the bevel, the metal at the edge is definitely thin enough to flex which I have photos of on some of my threads. I just picked up my small Joseph Allen wedge and the apex flexes under the thumb also, just nowhere near as severely as on a hollow grind and it occurs much closer to the apex because the mass of metal behind is inflexible. It's very small but if you're looking in the light right you can see it. I imagine a lot of wedges have more bevel reveal than they would have had from the factory so there's less hollowing behind their edge bevels than otherwise would be.
It's the sheer thinness of a hollow which allows it to flex behind the apex, the steel there is only about 5 to 7 thou thick sometimes thinner. On a wedge it is much thicker of course.
Are you getting more of a preference for the hollow grinds?
Just to add some food for thought. You could have a wedge razor with half the spine thickness as a full hollow (assuming the same width) but the wedge still wouldn't really flex anywhere near as much as the full hollow despite a much reduced bevel angle and apex width, you also wouldn't get the same feedback. A lot of how we feel about cutting tools and how they work is not really bevel angles and apex widths but the geometry and mass of material BEHIND the edge. Once the apex has cut into the object it can't really do anything else, you're then relying on the geometry of the tool to complete the act. A good well defined apex is the pry-bar that gets you through the door but beyond that it has minimal effect.
I'm getting in way over my head but...
If we are talking about measuring microns in the thickness of an apex, Wouldnt a razor made of harder steel be able to have a thinner apex than a razor made of softer steel? Can't the harder steel be refined to even a thinner apex? But then we get into the foiling issue being so thin.
It sounds like we are splitting hairs, of hairs, of hairs here. lol.
Maybe I'm just thinking too hard.
Yes, think we are too.Quote:
Originally Posted by Gasman
Bob
“An extra hollow grind has to have a finer edge than a near wedge, doesn't it? “
No, it’s not any thicker, they are the same size, they have to be. If both have an 18 -degree angle then the thickness of the apex is the same, but the thickness of the bevels is not the same, past the apex, because the wedge is exponentially thicker.
Wedges were made because it was easier and was good enough at the time, it was basically a knife. As grinding technology improved, blades could be ground thinner. A hollow ground gave a thinner edge cross section with the same mass at the spine.
Imagine a boat hull design of a rowboat and a cargo ship, if the hull angles were the same, the cargo ship would still require more force/power to plow through the same water, just because of the mass. I know that there is much more to hull design than hull angle, but imagine if both were Full-Displacement Hulls, wedge shape flat bottom. A full displacement hull gives up speed for smoothness, more of the hull remains in the water.
So, if we were cutting just one hair it would not matter much, but when we are cutting multiple hairs at the same time the mass bogs down, not much but enough for the shaver to feel it. You must push more steel not just through beard, but shave cream, water and some skin, or drag on skin.
Even with a hollow ground blade you feel it with each progressive pass. On a 3-pass shave. the first pass you feel more resistance because there is more hair to cut. The third pass is just cutting the hairs that laid down and much easier.
Does a wedge edge last longer than an extra hollow edge?..You can see where i am going with this :D
Probably, with most edge tools a thicker or convex bevel will last longer because there is more steel to support the edge.
Think Convex bevel and edge on an Axe as opposed to a thinner flat grind bevel.
But how much longer? Lots of variables that include quality of the steel and honing, stropping, technique and quality and cleanliness of the strop.
It is the “strop” that wears the edge more than the shaving use of a razor.
I will have an electron microscope one day and i look forward to it..The closer you can look the more info you can get.
I have to think now that an apex could not be measured though because it is the surface of the peak or peaks.
Therefore i am rite and so is everyone, case closed :shrug:
Cheers