How To How should I go about sharpening 20cv on the KME?

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Dr. Maguire

Joined
Oct 30, 2024
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Hello, this is my first post, so forgive any mistakes if I am posting in the wrong area or anything. I got a knife that I have wanted for a while. The knife in question is the Zero Tolerance Hinderer Carbon Fiber pocket knife or the ZT 0393GLCF. Here's the link. https://zt.kaiusa.com/0393glcf.html The steel is CPM 20CV. This is my first time sharpening this steel and I want to do it right.

I have been using the KME for about 2 years, mainly sharpening steels like 420HC, S30V, S35VN. But this steel seems to be different. I cannot get a sharp edge.

How do I sharpen this steel? Do I just need to do a lot of strokes? The last thing I want help on is stropping. I think I got the leather and diamond compound right. I just struggle with burr removal. How can I know for a fact that the burr is completely removed?

One note I would like to add is that I do have autism, so I might come off as odd in some posts. Any help is greatly appreciated.

Thanks.

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Welcome aboard D Dr. Maguire , yes this is the right forum for this issue.
In my experience, M390, 20CV, 204P steel doesn't form a distinct burr like the ones you mentioned. So, here's what I do, mark the bevel from the tip of the edge to the shoulder, then set your angle to what you think it is and adjust to remove the sharpie marks.
I use a KME also and find that on some steels I have to use way more strokes than on others. One you determine that you are indeed hitting the apex as well as the shoulder, then you should be good to go.
Make sure your stones are in good shape, free of build up and has life left in them. I just had to change my 300 diamond.
 
Ajack60 said:
Welcome aboard D Dr. Maguire , yes this is the right forum for this issue.
In my experience, M390, 20CV, 204P steel doesn't form a distinct burr like the ones you mentioned. So, here's what I do, mark the bevel from the tip of the edge to the shoulder, then set your angle to what you think it is and adjust to remove the sharpie marks.
I use a KME also and find that on some steels I have to use way more strokes than on others. One you determine that you are indeed hitting the apex as well as the shoulder, then you should be good to go.
Make sure your stones are in good shape, free of build up and has life left in them. I just had to change my 300 diamond.
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Thank you for the advice. How do I strop do it in mini sections or do it all in one sweep?
 
I have a 2" wide strop and use the length of the strop (8") for a slow continuous stroke to get the whole blade. On my kitchen knives, it may take a couple of passes to get the whole blade.
I have used the leather strop that KME has and to prevent from damaging the leather, I'll use the mini sweeps instead of trying a sweeping motion.
 
I borrowed a little USB powered microscope a while back for examining the edge as I was sharpening. It wasn't the most optically clear picture on the laptop but it more than sufficed to tell if the edge was really getting there or not. I've been swearing I would buy my own ever since.
 
Maximumbob54 said:
I borrowed a little USB powered microscope a while back for examining the edge as I was sharpening. It wasn't the most optically clear picture on the laptop but it more than sufficed to tell if the edge was really getting there or not. I've been swearing I would buy my own ever since.
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The best I have is a jewelers loupe 90x. How do I know if I am getting sharp?
 
Same way you'd sharpen any other steel, 20CV is nothing special. 99% of the time when people report this issue is because they're not reaching the apex of the edge. Since this is a new knife, factory edges are rarely consistently the same angle on each side or even on the same side, it may take time to "reset" the bevels, just keep at it. Use a permanent marker (KME even give you one) to paint the bevel so you know how you're progressing. After painting the edge, do a few passes, if you still see black towards the apex, you'll need to either remove more material or adjust the angle to be steeper. Since ZT's are fairly thick behind the edge it's gonna take a bit of time to remove material.

As for the burr, you'll be able to feel it when you run your finger across the edge. On the KME you're sharpening the top side, so feel for the burr with an upwards motion. It will feel like it's sharper going upwards than downwards, that's your que to start working on the other side.

Visually it looks like the apex is folding over to the side opposite of what you're sharpening.

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I invested in one their 100 grit stones when I had my KME. It was helpful on the tough steels, especially if doing a re-profile.
 
Dr. Maguire said:
The best I have is a jewelers loupe 90x. How do I know if I am getting sharp?
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The 90x loop should get you plenty close enough to show you if you have apexed the knife, as long as you have decent light to reflecting off the edge bevel. If you haven't reached the apex you will see a distinct line along the bevel indicating where the new grind lines stop and the old edge remains. That line will retreat towards the edge as you continue to grind, and when it's gone entirely, you've apexed the edge. At that point you should be able to feel a burr.
 
Dr. Maguire said:
The best I have is a jewelers loupe 90x. How do I know if I am getting sharp?
Click to expand...

I would assume 90X would be plenty. It's not so much about knowing if you're getting sharp as much as being able to see the whole length of the edge is done the same. I've found knives where I had about 95% of the edge just right only to miss that little bit towards the tip. Or I sliced some paper and couldn't see the spot but the paper found it. I guess this is more about perfecting your edge over just having a working edge.
 
Dr. Maguire said:
The last thing I want help on is stropping. I think I got the leather and diamond compound right. I just struggle with burr removal. How can I know for a fact that the burr is completely removed?

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What works for me is edge leading strokes only on the last 2 stones with very light pressure, intentionally trying to cut off any burr without flip flopping it. Following that I strop with moderate pressure. Not trying to bend the blade, but not just coasting either. You need the substrate to compress and wrap around the apex slightly. I do this on 3 micron strop followed by .5 micron. My burr issues went away since I've moved to this. I strop a good 10 passes each side on each strip, or maybe more. I'd rather give her a few more passes then have a burr left. Also don't hold the blade too low and not strop and hit the apex well. There's some great info on science of sharp about deburring and the lightbulb went off for me when he was showing how hanging denim strops deburred his razors.
 
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