I have been using a belt sander with various grits to sharpen my knives over the past few months. I have gotten pretty decent at getting an edge. I just got a loupe and have been looking at the edge and it appears I am sharpening all the way to the edge. One area I have problems is with the tip of the blade.
As I move towards the tip I have been lifting my arm up, keeping it in the same plane as when sharpening the belly. Should I also at the very tip, move my arm back towards me a little bit? It seems like this motion allows me to keep the same angle as I used on the belly of the blade. I just want to make sure that is the correct approach. Via the loupe, I find at the tip I am not grinding all the way to the edge at times and am simply wondering what the technique should be. I think part of my problem is that I am pulling the blade off the belt too soon. I read on this forum to pull the tip off before or at the midway point of the belt to prevent rounding off the edge. I think I have been pulling it too soon, though, but it could also be the movement of my arm (up, or up and out) as I approach the tip. Any advice would be appreciated.
The other thing I am wondering about is why some of my cheap knives don't hold an edge very long. For example, this is my first year trapping beaver and I have been using the following two knives for skinning.
http://www.fntpost.com/Products/Knives/Chicago+Cutlery+4+Blue+Skinning+Knife
http://www.fntpost.com/Products/Knives/Dexter-Russell+Beaver+Skinning+Knife
Both get dull pretty quick. I usually touch them up after skinning one beaver, although they could probably do two before having to sharpen them. The Chicago Cutlery knife tends to dull quicker then the Dexter Russell. Is this quick dulling due to the cheapness of the blade? I have been starting with a Trizact A45, moving in order to an A20, A6, A3, leather with green compound, and leather with white compound. Only recently have I added in the A6, A3, and leather with white compound. They don't seem to make my edge last longer and I am thinking about going back to using an A45, A20, and finish with leather with green compound. From reading here, I draw my blade against my pine fleshing beam/bench to remove the wire edge after using each belt. I can tell this helps to remove some of the wire edge as it feels rough when I first start drawing it through the pine and then after 2-3 pulls it gets smooth. In an earlier thread I was complaining about my blades not keeping and edge and someone suggested it could be there is a wire edge that wasn't fully removed, thus my new approach. Is there any advice someone can offer me to improve the time between sharpening for these blades or is their low cost possibly a reason that they don't stay sharp for long?
Finally, from rereading John Juranitch Razor Edge Sharpening book, I get the impression that over time, by sharpening a blade I make the angle of the edge greater. That is, as I take off more metal through repeated sharpenings, the edge moves closer to the spine, which is thicker than the the original edge. When do I need to reprofile a blade so that edge remains thin (or at the same angle when it was new, assuming this was an appropriate angle to begin with)?
I appreciate any help you can provide. I can get some of my knives to shave hair (kitchen) and the others pretty sharp, but it seems like my technique isn't fully sound or repeatable consistently. My knife edges don't seem to last that long. The kitchen knives last 2-3 weeks, before I resharpen them, but like I said, the skinning knives get dull fairly quick. Also, as a point of reference, I don't use a steel to lengthen the time between sharpening. I know I should, but that is another thing to learn how to do well, and I want to focus on learning the belt sander first.
As I move towards the tip I have been lifting my arm up, keeping it in the same plane as when sharpening the belly. Should I also at the very tip, move my arm back towards me a little bit? It seems like this motion allows me to keep the same angle as I used on the belly of the blade. I just want to make sure that is the correct approach. Via the loupe, I find at the tip I am not grinding all the way to the edge at times and am simply wondering what the technique should be. I think part of my problem is that I am pulling the blade off the belt too soon. I read on this forum to pull the tip off before or at the midway point of the belt to prevent rounding off the edge. I think I have been pulling it too soon, though, but it could also be the movement of my arm (up, or up and out) as I approach the tip. Any advice would be appreciated.
The other thing I am wondering about is why some of my cheap knives don't hold an edge very long. For example, this is my first year trapping beaver and I have been using the following two knives for skinning.
http://www.fntpost.com/Products/Knives/Chicago+Cutlery+4+Blue+Skinning+Knife
http://www.fntpost.com/Products/Knives/Dexter-Russell+Beaver+Skinning+Knife
Both get dull pretty quick. I usually touch them up after skinning one beaver, although they could probably do two before having to sharpen them. The Chicago Cutlery knife tends to dull quicker then the Dexter Russell. Is this quick dulling due to the cheapness of the blade? I have been starting with a Trizact A45, moving in order to an A20, A6, A3, leather with green compound, and leather with white compound. Only recently have I added in the A6, A3, and leather with white compound. They don't seem to make my edge last longer and I am thinking about going back to using an A45, A20, and finish with leather with green compound. From reading here, I draw my blade against my pine fleshing beam/bench to remove the wire edge after using each belt. I can tell this helps to remove some of the wire edge as it feels rough when I first start drawing it through the pine and then after 2-3 pulls it gets smooth. In an earlier thread I was complaining about my blades not keeping and edge and someone suggested it could be there is a wire edge that wasn't fully removed, thus my new approach. Is there any advice someone can offer me to improve the time between sharpening for these blades or is their low cost possibly a reason that they don't stay sharp for long?
Finally, from rereading John Juranitch Razor Edge Sharpening book, I get the impression that over time, by sharpening a blade I make the angle of the edge greater. That is, as I take off more metal through repeated sharpenings, the edge moves closer to the spine, which is thicker than the the original edge. When do I need to reprofile a blade so that edge remains thin (or at the same angle when it was new, assuming this was an appropriate angle to begin with)?
I appreciate any help you can provide. I can get some of my knives to shave hair (kitchen) and the others pretty sharp, but it seems like my technique isn't fully sound or repeatable consistently. My knife edges don't seem to last that long. The kitchen knives last 2-3 weeks, before I resharpen them, but like I said, the skinning knives get dull fairly quick. Also, as a point of reference, I don't use a steel to lengthen the time between sharpening. I know I should, but that is another thing to learn how to do well, and I want to focus on learning the belt sander first.
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