Thread: Apex Width

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.

Originally Posted by Gasman

It sounds like we are splitting hairs, of hairs, of hairs here. lol.

Yes, think we are too.

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

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
Cheers