Hemp rope vs. paper on a blade

Leu Custom

Leu Custom

Joined
Jun 2, 2007
Messages
1,354
I have a question for all you knife gurus out there. Why is it that when I cut paper with my blades, it almost appears a very very small wire edge appears (which I can actually strop off with a cotton t-shirt), but when I'm using it to cut 1" inch hemp rope, almost nothing appears (that I can feel with my thumb nail? Is the paper actually more abrasive them then hemp rope? You would think it's the other way around right? Any information would help!
 
how about filling out your profile so we know a little more about you. what knife are you using to cut paper with?
 
What would you like to know Richard? I'm using a blade made of A2 steel that I ground, heat treated in a kiln and tempered 3 times. I live in Southern California, doing this as a hobby less than even part time :D i'm 31 years old. The blades have no secondary bevel on either chisel or double ground blades and um well that's about all I can think of. :D
 
Well, is it possible that the wire edge was there to begin with, the paper was harsh enough to deflect it so that you could see it, but the hemp was tough enough to break it off?

If you examine the edge with a lens prior to any cutting, do you see a wire edge?

Perhaps a modification of your sharpening technique to remove the wire edge before any cutting? Bear with me. I'm just guessin'.
 
The wire edge was not there before cutting the paper. My thumb nail does not drag on the blade when i run it over. After cutting the paper, cardboard, magazine page, clearly when you try to run your thumb nail over the blade again, it kinda drags on the nail. After a light stropping on my cottong t-shirt, the wire edge is gone again and my thumb nail once again glides over on the cutting edge. Is this normal? or do blades generally not cut paper very easily? I'd have to classify the blades as shaving sharp, but with no actual wire edge prior to cutting paper materials. Sure I could get it rockwell hardness tested. What is that going to tell me other than the hardness of the blade? Thanks!
 
Sounds like you have the worlds finest wire edge and the hemp rope wore it righ toff.
 
No it is not normal for a properly sharpened or heat treated A2 blade, or any other steel, to get a rolled edge from slicing paper. If your sure you have removed the wire/burr from sharpening you probably want to check your heat treatment on the blade. A RC test would be one good way to check it.
 
I don't think the edge is actually rolled over. it is almost like a microscopic edge that is sticking exactly straight to the edge itself. it is not rolled over to either side of the blade and a very very light stropping will take it off.
 
No that is not normal behavior for a properly sharpened and heat treated edge.
 
How are you sharpening the knife and to what grit? It sounds like you are using a butchers steel which will deform the edge but not remove the burr properly.
 
It sounds to me like you have a very fine burr or wire edge. When you strop on the cotton T-shirt, you are not removing it. You are just bending it back into alignment with the blade. It is so thin that even slicing paper will bend it again. Cutting hemp rope will probably remove it completely.

Tell us this: If you cut a few pieces of hemp with no burr appearing and then (without sharpening) slice a piece of paper, does a burr appear?
 
your knife might be too soft to keep an edge very long. i would find out the rockwell of your blade. have it tested in a few spots. i cut up an entire shoebox with a knif i made and still shaved with it after i was done.
 
richard j said:
your knife might be too soft to keep an edge very long. I would find out the rockwell of your blade, have it tested in a few spots. I cut up an entire shoe box with a knife I made and still shaved with it after I was done.
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In fact: I think you could cut up a car with one of Richards' knives and then still shave with it. The most Hard, sharpest knife I have ever owned. Keep in my desk just to be ready to cut up the scrap pallets we have laying around. Then doing my afternoon shave. 4 o'clock shadow. Never felt a wire edge, but I do keep a first aid kit handy with lots of bandaids. :D:D:D
 
i don't think the edge is "too soft" as it can cut a piece of 1" inch hemp over 150 times nice and cleanly. Could it be that the edge has a zero grind and no secondary bevel to it? the blade angle is 20' degrees and some are 15' degree. Cutting up paper, an entire phone book is no problem with it. It will still shave the hairs off my arms no problem, but it seems to again develop a microscopic burr or maybe it's not even a burr at all.
 
db said:
No it is not normal for a properly sharpened or heat treated A2 blade, or any other steel, to get a rolled edge from slicing paper.
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I agree. A wire edge isn't going to become apparent after cutting paper, or anything for that matter, unless if was there to begin with.

Some blades, due to steel and/or heat treat, can be very bad about forming stubborn wire edges. Personally I've come to believe that most blades showing any significant tendency to form burrs really aren't worth the effort anyway because they'll generally have far below optimum edge retention even if you manage to clean up the wire edge.
 
Cliff: no you cannot see the wire-edge...i can only feel it with my thumb nail as I drag it over the edge.

I am sharpening the blade to ZERO ground with no secondary bevel with a buffer using buffing compounds to polish and another compound to actually sharpen the edge with. The edge is ever bit as hard as any other edge. The reason I know this is because when I take a blade made from a kitchen knife and try to press it against to see if i can dent the blade, the blade dents a little and puts a nice NICK into the kitchen knife.

The steel is A2. Not any weird butcher steel or whatever.

The odd part is it only does this to blades I have ground chisel ground and the double ground blades don't seem to develope a burr. I know the blade is HARD because a steel dremel bit can't even bite into it. It takes a tungsten carbide bit to engrave into it.
 
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