Shaving sharp ?

K

Kevin the grey

Joined
Aug 26, 2005
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How sharp is sharp ? I sharpen my knives until they can shave the hair off my arms . Unless abused this entails a touch up with a fine ceramic stone .
I don,t go farther than this cause it seems to be what I need . It is sharp enough to field dress a deer with my favourite pocket knife without resharpening .

How much sharper must it be to shave a face ? How much does the hollow ground configuration of a straight razor contribute to its ease of use ? Is it not just a question of sharpness but consistancy of edge as well ?
 
I guess it would depend on the knife, in my case. All of my pocket knives will cleanly shave the hair off my arms without a dragging feeling. My multi-tools, SAKs, and Spydercos get this degree of sharpness.
My presentation khuks as well as my straighter bladed HI knives like the seax and bowie get at edge that will shave hair, and slice paper, but maybe not the whole edge and not as polished as the pocket knives.
My working khuks like my full sized GRS, WWII, M43, etc get a sort of toothy kinda-sorta polished sweet spot and left toothy on the rest of the edge. Basically, i run then a few times down the rougher side of a butcher's steel, then a few times down the smoother side, then I knock off the bur with the rough side of a old belt strop. they'll still slice, but it's like sawing the material instead of severing. if you cut yourself with these blades it feels just like a paper cut, except the cut is a little bigger;)

Jake
 
Kevin, a shaving (as in shaving your face) edge is a very fine and delicate thing, one slice through a piece of cardboard would literally wipe it out. How sharp is no joke shaving sharp? A properly honed and stropped razor should have no difficulty cleanly severing a free hanging single strand of hair. If the edge skips off and just pushes the strand of hair out of the way, it still needs further attention. With a top of the line, double hollow ground, "singing" (those who know what I'm talking about, know what I'm talking about ;) ) straight razor, you can actually hear the individual hairs pop as you stroke it across your cheek. A bit unsettling until you get used to it. :D

Sarge
 
I like my khuks sharp enough to take hair off my arm, and to have the edge somewhat polished to avoid a lot of sticking.
 
there's shaving sharp

and then there's murderously sharp. :D




"shaving hair above the arm" is generally considered excellent sharpening. (similar to what sarge said)
 
By double hollow ground I am presuming it to mean that both sides of the blade are hollow ground as oppsed to one ? I have only seen one razor and I thought all razors were made like that . Now that you mention it I can see that the second hollow would allow the blade to sit closer and perhaps even stretch the skin a little more ? It is something that I am going to try out . I want to do it the right way and it may take me a while to get the blade I want . Is it a test of fortitude to shave with ones own knife or is it fairly easy ? I saw an ultrathin supposedly hi-carbon carving knife at the flea market . Is that exactly the opposite way to go or is it a good way to practice sharpening and shaving with ?
 
Kevin, double hollow ground means more than just being ground on both sides. The blade is actually hollow ground twice with different diameter wheels. Here's an excerpt from an article published by Dovo, the German razor makers. It explains what I'm talking about.

PRINCIPLES OF STRAIGHT RAZOR GEOMETRY In the beginning straight razor blades were wedge shaped, the sides of the blade were straight lines, not concave (hollow). These blades shaved as perfect as the later hollow ground blades, if sharp, but had some disadvantages. First, they were heavy, compromising balance. Second, due to the wedge shape, the sides of the blade above the cutting edge instead of the edge itself, primarily touched the hone surface while honing. Third, after years of daily use, the regular honing caused rapid thickening of the edge width, thus making sharpening increasingly difficult and time consuming. Therefore, the next step was to clear the blade sides from the hone surface, in order to reduce weight, and to use the back as a guide for keeping the correct angle of the cutting edge, with which it forms one plane. This was done by grinding away metal between the cutting edge and the back with a wheel, resulting in a biconcave, hollow ground blade (at first without a ridge), combining an extremely thin blade with a very small cutting angle under 15 degrees. The disadvantage of this second step without a ridge was, that the ultra thin biconcave blades were unstable in the direction perpendicular to the plane of the blade. Therefore the third step was to create a ridge parallel to the cutting edge, dividing the blade in two parts: an upper part between back and ridge, and a lower part between ridge and cutting edge. The ridge is created by grinding the raw triangular basic form with successive different wheel diameters: the greater wheel for the part between ridge and back; the smaller wheel for the part between ridge and cutting edge.

The result consists of two hollow grind blade divisions separated by a thicker ridge, with hardly visible smooth transitions. The closer the ridge is to the back, the more the type goes from =BC to 1/1 hollow grind. The ridge presents stability and vibrations which add to cutting performance, which can be identified by transversely rubbing the thumb carefully over the edge, causing a ringing sound. The ridge is not that thick that it touches the hone, of course, and you can hardly see or feel it. The three parts (two concave parts separated by the ridge) are identified under a sharp light: the ridge diverges the light and is therefore identified as a linear shadow, parallel to the edge. The full hollow grind blades have the ridge at about a little below halfway between back and edge; lower grades of hollow ground just behind the edge, or somewhat further to the middle of the blade. A full (1/1) hollow ground blade keeps a very thin edge even after a lifetime of honing and stropping; a =BC ground blade edge rapidly thickens after years of honing, because of the proximity of the ridge to the edge.

Sarge
 
Holy frijoles , I,m going to have to read that a time or two . I was getting what was said up to the point where I thought the ridge was to change the radius of the hollow ground . Neat stuff ! I wonder if this idea was first thought of or that it came through experimentation . When I first started with cutting implements I in truth thought of them as pointy bits of metal that I could poke holes in things with . It was then pointed out to me that
it might perhaps be better if I put an edge on that thing . I,ve come a short way since then . I,ll have to look over that overview again as there is more to it than meets the eye. thanks .
On a separate note , it will be some time before I find the razor that I want . In truth what you have shown today will widen my hunt even more .
I saw an almost literally razor thin carving knife . The blade actually wobbled with a wag of the handle . I was thinking of shortening it up and making it into a pseudo razor . The blade seems to be very high carbon and in fact the brand name is Hii-carbon . Am I asking for a world of misery in attempting this ? I think I will rescue the blade as it is only fifty cents and make the razor if I can . Am I going to be a sad puppy when I attempt a shave ? I have to admit I have a very tough beard . Some of my more intimate companions think of it as sandpaper while others can,t stop giggling ! Go figure ! L:O:L .
 
Singing razors ? Hair popping sharp ?

And now for the opposite end of things . As I said I sometimes deal in antiquities and collectables in a very small manner . Most often passing them on to those who will appreciate them . Barter for the most part , as that is my wont . I have come across what may be the precursor to the safety razor . Picture a thin flat surface somewhere between a whetstone and a strop . Put this surface in a 2 inch by 4 inch frame with a guide/slide track along two sides This has a handle that rolls/slides along this track and just over the whetstone . A razor blade is temporarily attached to the handle and the handle is pushed over the whetstone surface . This pushes the razor along over the surface with a uniform pressure and evenly from side to side . When you pull back on the handle the razor flips over on the track and you sharpen the other side . This razor blade is then attached to a handlewith no guides as to angle or a safety limiter as to depth of cut ! Oops !
The only pretty part of this is the razor itself which is a formidable affair . To call it hollow ground is to say the least ! There are few identifying marks except on the razor itself which is identified as a Rolls razor . I know most here will not have shaved with the original safety razor which was a beast in itself . This little gem while beautiful as to blade lets us know what it must have been like before all the safeguards were put inplace to save us from ourselves ! L:O:L
 
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