Quick help question on sharpening one part of the blade?

R

realitycheck

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Nov 24, 2007
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I dont know the name of this section of the blade its the first part of the edge right after the kick. Anyway im trying to reprofile my spyderco delica four. I've ran into this problem before while reprofiling holding the knife perpendicular to the stone and making strokes that way it doesnt get to this section of the blade. It seems by the time I took away enough metal to get to that part of the blade the edge would over a 1/4" up the side of the blade. So in the past I have rotate the tip of the knife toward me while sharpening to try and reduce this. Sharpening this one it just doesnt seem to be working. How do you guys reprofile this section???
 
Generally I like to have the edge angle the same over the entire length of the edge. Often times you find the factory edge is more obtuse both near the tip, and at the very rear portion like you describe, so that often means reprofiling those areas more than the rest.

What you're describing sounds more extreme than usual, as though the entire blade grind is thicker at the back. In that case I don't see any problem with leaving the primary bevel in that area more obtuse than the rest. I would at least try get both sides under 20 degrees, of course a 15 degree primary or less would cut better, but sometimes you have to adapt to what you've got to work with. :) If you ever did need to use your Delica to cut something really tough like some cable or heavy copper wire, that thicker back portion might just prove to be handy.
 
Dog of War said:
Generally I like to have the edge angle the same over the entire length of the edge. Often times you find the factory edge is more obtuse both near the tip, and at the very rear portion like you describe, so that often means reprofiling those areas more than the rest.
QUOTE]
Dog of war I completely understand what your saying I often thought that this just due to the shape of the blade. Maybe im wrong, anyway I guess i'll just keep rotating the tip towards me and try to minimize this situation. But like you said you just got to work with what you got, and you got to do what you got to do. :thumbup:

nose here is a pic of a balisong where the guy points to it he call it a kicker but same thing.
450px-Parts_of_a_balisong3.jpg
Click to expand...
 
Thanks. I was just googling knife anatomy. Anyway, I had the same problem reprofiling my Endura. I was using a DMT d8xx, and the edge on that stone is rounded so it wouldn't get in there. It drove me nuts as it was creating a slight concave just passed it that wouldn't get sharp. This sounds like the problem you are having. Your flat stone isn't touching the concave section of the edge.

To fix it, I set my Aligner clamp all the way toward the base of the spine. I placed a strip of heavy duty clear packing tape lengthwise covering half of my xcoarse stone for my Aligner. I then filed away at the section where the grind ends pressing the edge of my stone right up to the edge of the grind termination. My goal was to create a hollow there. I think I saw someone on here describe it as making a mini choil. I had to keep an eye on the tape to make sure I hadn't sliced it away. The tape served to raise the stone ever so slightly to make it cut in just the right spot against the grind termination. I wasn't worried about taking too much metal off there. As soon as I had the slightest hint of a depression, I quit. This made it quite easy to sharpen in the future.
 
Thank you nose for your idea. Thinking about what you said and what I was telling dog of war. I was thinking how the blade was shaped and because of the belly of the knife I believe that it actually holds that section of the blade off the stone while you hold it level. So I put the knife on the stone and then pushed down toward that part of the edge, and it actually started cutting it there. Instead of just barely touching it and constantly cutting the belly. Thanks for the help guys. I still wish I knew a name for this section of the blade, does anyone know?
 
realitycheck said:
Thank you nose for your idea. Thinking about what you said and what I was telling dog of war. I was thinking how the blade was shaped and because of the belly of the knife I believe that it actually holds that section of the blade off the stone while you hold it level. So I put the knife on the stone and then pushed down toward that part of the edge, and it actually started cutting it there. Instead of just barely touching it and constantly cutting the belly. Thanks for the help guys. I still wish I knew a name for this section of the blade, does anyone know?
Click to expand...
Yeah, I've run into this ... with some knives you need to just focus on putting pressure on that part of the edge. I'm sure what happens on edges like this, meaning without a choil, is that at the factory they're applying that portion of the edge with only the edge of the belt on the grinder, so the pressure and cutting action is a little slower, and the edge bevels just don't get applied as completely right in front of the kick.

I've never heard a formal name for it, I just call it the very back or rear portion of the edge; edge in front of the kick describes it perfectly, IMO.

BTW, one thing to consider before adding a choil, when cutting some things like thin materials or cord, you can get snagged on the choil. If you use your blade a lot, and tend to slice with the whole edge, this can be a problem and slow you down when working. But it does make sharpening easier, and on some knives can be a nice feature.
 
Dog I learned this on my benchmade mini grip when opening plastic bags and like you said cutting cord I learned real quick it gets caught. So I actually prefer to not have one. I also noticed like you said it makes it way easier to sharpen. But since you use the knife a whole lot more than you spend sharpening it. I prefer it without the tiny choil right after the kick. thanks for all the help guys.
 
I just wanted to clarify that I'm not suggesting grinding a bonafide choil where the edge meets the kick, I'm just saying concentrate on that area until you have the edge ground back just slightly farther than the edge right next to it. I'm talking about only enough to notice it if you laid it on a flat stone and saw a little light in between that small section of edge and the stone. On my Endura, this section is about 1/8 inch in length and can't be noticed by looking at it, however it creates a slight belly to start my sharpening stroke against, slightly passed the 1/8" of hollow I ground into it. This being hassle free compared to trying to sharpen a slight concave with a flat stone. I do believe however that we are talking two different things. You want to sharpen that first 1/8 of an inch while I am nocking it down to eliminate problems just passed it. With what I am descibing, that first 1/8 of an inch still has an edge, however it isn't a nice refined edge as I am not trying to get it razor sharp. My razor sharp edge begins at the high point of this mini belly, just slightly passed the 1/8" area.

Anyway, it looks like you have figured it out. I wasn't sure by looking at the Delica pictures if the edge has belly to it along it's entire length. My Endura starts out straight, and then transitions into a belly. This creates the particular issue that I had to deal with.
 
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