Cpm-20cv won’t sharpen to razor edge...

KnifeCarsen10

KnifeCarsen10

Joined
Sep 12, 2018
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167
Hey guys, I’m just wondering why I can’t bring back the edge I once had on my Benchmade 551-1 in 20cv. When I received it, it was very sharp. I could easily shave hair and push cut magazine paper. Now I can’t seem to get it back to that edge. My sharpening supplies include: Worksharp Diamond Sharpening system, with a 17 degree and a 20 degree angle guide. The grits are 240 and 600. Included with the set is a “coarse” ceramic and a fine ceramic rod guided at 25 degrees. I also have a 1000 grit Arkansas stone. To finish it off, I have a leather strop loaded with green compound. I have white compound but don’t use it. I use the smooth side of the leather. I also tried stropping on cardboard, magazine paper, and smooth wood. Please let me know how to get a hair whittling edge. Thank you very much!
 
KnifeCarsen10 said:
Hey guys, I’m just wondering why I can’t bring back the edge I once had on my Benchmade 551-1 in 20cv. When I received it, it was very sharp. I could easily shave hair and push cut magazine paper. Now I can’t seem to get it back to that edge. My sharpening supplies include: Worksharp Diamond Sharpening system, with a 17 degree and a 20 degree angle guide. The grits are 240 and 600. Included with the set is a “coarse” ceramic and a fine ceramic rod guided at 25 degrees. I also have a 1000 grit Arkansas stone. To finish it off, I have a leather strop loaded with green compound. I have white compound but don’t use it. I use the smooth side of the leather. I also tried stropping on cardboard, magazine paper, and smooth wood. Please let me know how to get a hair whittling edge. Thank you very much!
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Rule out burr formation and burr removal.

Then rule out angle variation.

If your creating a burr, removing it properly and limiting the angle variation. You will have what your looking for.

A sharp edge.
 
DeadboxHero said:
Rule out burr formation and burr removal.

Then rule out angle variation.

If your creating a burr, removing it properly and limiting the angle variation. You will have what your looking for.

A sharp edge.
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Can create and remove a burr with a strop? What’s the exact method you strop your knives? Thanks
 
KnifeCarsen10 said:
Can create and remove a burr with a strop? What’s the exact method you strop your knives? Thanks
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No stropping only enhances it doesn't create.

No, stropping should not be the first line to remove burr. You have to reduce the burr on the last stone used with edge leading or edge trailing passes, alternating sides every pass (no counting)
Do it until the burr is reduced or removed

if done properly some steels will even have the burr break off in one long strip from this method, but it's not always common.

Once the burr is reduced and weakened it can be removed with a leather strop.

The cleaner you remove the burr on the stones the better. Use the strop as an enhancer not as a crutch to remove burr.
 
This edge was
400 CBN waterstone
1500 CBN waterstone

Burr was removed off the 1500 stone.

Then strops from 1um to 0.25um diamond on leather was used.

 
K.C. 10,
20CV (M390) should take (does take) one of the best long term carvy edges.
Keep at it.


Sir DBHero,
That was some pretty hair whittling going on there. NO QUESTION ABOUT IT !
What say . . . how does it do on something a little less forgiving ? I'm talking a test of edge geometry now.

You know me I have a strong aversion to strops.

I find the Edge Pro Edges (no strop) tends to trim firmer material better than a free hand sharpened or stropped edge.
Do you dare ? :) :rolleyes:

IMG_4287.jpg
 
DeadboxHero said:
No stropping only enhances it doesn't create.

No, stropping should not be the first line to remove burr. You have to reduce the burr on the last stone used with edge leading or edge trailing passes, alternating sides every pass (no counting)
Do it until the burr is reduced or removed

if done properly some steels will even have the burr break off in one long strip from this method, but it's not always common.

Once the burr is reduced and weakened it can be removed with a leather strop.

The cleaner you remove the burr on the stones the better. Use the strop as an enhancer not as a crutch to remove burr.
Click to expand...
So I take my knife back and forth on my ceramic rod how many times on the coarse and the fine. Sometimes it is very obvious to feel the burr even with my finger, but other times when I put my nail right on the edge, it feels different.
 
DeadboxHero said:
No stropping only enhances it doesn't create.

No, stropping should not be the first line to remove burr. You have to reduce the burr on the last stone used with edge leading or edge trailing passes, alternating sides every pass (no counting)
Do it until the burr is reduced or removed

if done properly some steels will even have the burr break off in one long strip from this method, but it's not always common.

Once the burr is reduced and weakened it can be removed with a leather strop.

The cleaner you remove the burr on the stones the better. Use the strop as an enhancer not as a crutch to remove burr.
Click to expand...
Will a ceramic rod sharpen my knife enough so using a strop will make it hair whittling sharp?
 
Here is a video I made two years ago using the same system. I'm using a different steel but it doesn't matter. In fact 20cv will take a better edge and deburr much better then the 8cr13mov I'm using in the video.


Cross reference the information in the video with what I said here. Also there are more Sharpening videos you can watch on my channel and tons of information in the stickies to read.

At the end of the day what keeps people from getting an edge is wayyyy too much angle variation.

2. Not forming a burr on one side then the other.

3. not removing the burr properly.

So just practice. It's not the steel or the system you're using that's holding you back.


KnifeCarsen10 said:
Will a ceramic rod sharpen my knife enough so using a strop will make it hair whittling sharp?
Click to expand...
 
KnifeCarsen10 said:
Benchmade
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Here is a vid I stumbled across tonight while looking for something non knife related.
Talks about Benchmade and also my favorite topic; geometry and he says he thinned his Benchmade down to 20 thou. Heck that's where I tend to start thinning stuff and go down from there to improve them. He talks 7 thou as well . . . now we're talking !

Anyway more food for thought about your Benchmade.
 
I use either dmt diafold green/tan, or freehand the spyderco sharpmaker ultrafine. I’m sure I’m the worst at sharpening in terms of the language/understanding of burrs, wire edge, etc, but I bring then back to sharp in literally minutes and they stay sharp for a long time. I just go slow and soft.
 
DeadboxHero said:
Here is a video I made two years ago using the same system. I'm using a different steel but it doesn't matter. In fact 20cv will take a better edge and deburr much better then the 8cr13mov I'm using in the video.


Cross reference the information in the video with what I said here. Also there are more Sharpening videos you can watch on my channel and tons of information in the stickies to read.

At the end of the day what keeps people from getting an edge is wayyyy too much angle variation.

2. Not forming a burr on one side then the other.

3. not removing the burr properly.

So just practice. It's not the steel or the system you're using that's holding you back.
Click to expand...
Wow! Awesome video!! Thanks!
 
Maybe the cardboard is rounding your edge on the channels? Also would highly recommend diamond pastes or sprays instead of compound for the stropping on 20cv. As it's harder and has Vanadium carbides the diamonds will leave it nice and grabby. But otherwise the advice above is solid.
 
Thin out the blade first then sharpen edge!most knives are too thick behind the edge and thats why youre bot getting maximum sharpness and cutting performance
 
Are some of your stones flat and some not true flat ?
I finally got around to watching this one. I keep my stones very flat out of habit because I have to keep the backs of woodworking edge tools flat which tend to be "chisel" ground (flat on one side / no bevel on one side.
So . . . this vid is preaching to the quire with me but I was curious what all he had to say. Murray Carter has a lot of good things to say, in his vids (this isn't a Carter Vid) but Mr. Carter makes me crazy with some of his habits and flattening stones by trying to sharpen on the high spots AND MAKE THEM FLAT THAT WAY is . . . lets say . . . questionable . . . as Cliff says here.
 
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I have found that stropping high carbide content steels takes away that final "bite" after sharpening. I get the best results on D2/S30V/CTS-XHP/S110V/20CV by honing on an ultra-coarse DMT (220 grit), then finishing with a few light strokes on DMT fine (red, 600 grit). Stropping (I use green chromium oxide) works OK with high carbon steels, though.
 
Alberta Ed said:
I have found that stropping high carbide content steels takes away that final "bite" after sharpening. I get the best results on D2/S30V/CTS-XHP/S110V/20CV by honing on an ultra-coarse DMT (220 grit), then finishing with a few light strokes on DMT fine (red, 600 grit). Stropping (I use green chromium oxide) works OK with high carbon steels, though.
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Ya gotta upgrade to 1um diamond spray
 
I have similar issue with diamond. Some steels don't get their edge until I hit 1500 grit stone. It's the same with M390 which I believe is similar to 20CV.
 
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