Not so super steel?

P

Paul the snobby bandit

Joined
Feb 24, 2021
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I'm looking for advice here.

I got a Spyderco Gayle Bradley 2 with CPM-M4 a couple months ago, which is the first premium steel I've used. I polished it up hair-popping sharp on my edge pro (all the way up to 6000 on the factory angle, which was about 15°). By all reports that I've heard, it should have some pretty phenomenal edge retention, but honestly, it hasn't seemed super incredible to me.

I imagine that I'm doing something wrong here. Is the 15° factory angle a bad idea I need to correct? Is taking it up to 6000 a bad idea? I'm all ears.
 
Paul the snobby bandit said:
I'm looking for advice here.

I got a Spyderco Gayle Bradley 2 with CPM-M4 a couple months ago, which is the first premium steel I've used. I polished it up hair-popping sharp on my edge pro (all the way up to 6000 on the factory angle, which was about 15°). By all reports that I've heard, it should have some pretty phenomenal edge retention, but honestly, it hasn't seemed super incredible to me.

I imagine that I'm doing something wrong here. Is the 15° factory angle a bad idea I need to correct? Is taking it up to 6000 a bad idea? I'm all ears.
Click to expand...

IMO, 6000 grit is great if you want to whittle hair or push-cut toilet paper, but I personally find a less polished edge to be more useful for real world cutting chores.
I've used CPM M4, and it really does hold an edge for an extremely long time. But I don't take it anywhere near that polished.
I stop at a DMT extra fine stone, which is ~1200 grit. 15 deg per side is about what I use.
 
Paul the snobby bandit said:
I'm looking for advice here.

I got a Spyderco Gayle Bradley 2 with CPM-M4 a couple months ago, which is the first premium steel I've used. I polished it up hair-popping sharp on my edge pro (all the way up to 6000 on the factory angle, which was about 15°). By all reports that I've heard, it should have some pretty phenomenal edge retention, but honestly, it hasn't seemed super incredible to me.

I imagine that I'm doing something wrong here. Is the 15° factory angle a bad idea I need to correct? Is taking it up to 6000 a bad idea? I'm all ears.
Click to expand...
Regardless of the steel, I don't think there are any steels that hold a hair popping edge for any great amount of time. That's my experience anyway.

The difference between something like M4 and a lower alloy ingot steel, is that the working edge should last a lot longer. This is all somewhat subjective though.

As far as level of polish, in my experience the edge retention is not enhanced by polishing. You might find small increases in sharpness, but in my experience the effort is not worth it as far as edge retention goes.
 
I had an M390 blade brought up to hair splitting on a 6000 grit. That polished edge lasted about a day. As others are saying, the super bit seems to apply to the working rather than polished edge.
 
I've never cared about hair popping sharp or whatever. Ultra fine stones on my sharpmaker is as far as I go. I used my GB1 a lot in the first few years I had it, but since mid 2016 I've trended towards lighter weight knives. However, the edge retention has been very good, and very little maintenance. Got some surface rust on it (and the frame) while it sat for a year in a drawer for a year while I was in the hospital. I never use it or carry it. But I have a hard time getting rid of it. It was my first Spyderco, as well as the first knife I bought after joining blade forums back in 2013. Used and a bit beat, but it's a good steel. I think maybe you took the sharpening a bit too far.
 
There's the whole thing where a 15deg edge will be sharper, but not last as long as say a 20deg edge. Even at the same polish level.

Then there's the fact that the working edge is going to last longer than that razor edge. I like stupid sharp knives too. I like polished edges and bevels.

You could try to put a micro bevel on it to help the working edge have a little more stability and take advantage of geometry.

Like others have said, these high end steels do hold a good edge a long time....that razor edge is inherently weak compared to the working edge.
 
co556guy said:
There's the whole thing where a 15deg edge will be sharper, but not last as long as say a 20deg edge. Even at the same polish level.

Then there's the fact that the working edge is going to last longer than that razor edge. I like stupid sharp knives too. I like polished edges and bevels.

You could try to put a micro bevel on it to help the working edge have a little more stability and take advantage of geometry.

Like others have said, these high end steels do hold a good edge a long time....that razor edge is inherently weak compared to the working edge.
Click to expand...
chalby said:
Regardless of the steel, I don't think there are any steels that hold a hair popping edge for any great amount of time. That's my experience anyway.

The difference between something like M4 and a lower alloy ingot steel, is that the working edge should last a lot longer. This is all somewhat subjective though.

As far as level of polish, in my experience the edge retention is not enhanced by polishing. You might find small increases in sharpness, but in my experience the effort is not worth it as far as edge retention goes.
Click to expand...

Also, what these guys said.
 
I've found my GB2 cuts best with a slightly coarser edge - I stop at DMT red (600 grit). It will take a finer edge on the DMT green (1200 grit) which is fine for eviscerating Covid viruses:D but it doesn't have the same 'bite' at that level.
 
Paul the snobby bandit said:
....... I polished it up hair-popping sharp on my edge pro (all the way up to 6000 on the factory angle, which was about 15°). By all reports that I've heard, it should have some pretty phenomenal edge retention, but honestly, it hasn't seemed super incredible to me.
Click to expand...

What are you cutting / how long are you cutting said material until your "hair-popping" edge is gone? I'm thinking there may be a wire edge / burr?
 
co556guy said:
There's the whole thing where a 15deg edge will be sharper, but not last as long as say a 20deg edge. Even at the same polish level.

Then there's the fact that the working edge is going to last longer than that razor edge. I like stupid sharp knives too. I like polished edges and bevels.

You could try to put a micro bevel on it to help the working edge have a little more stability and take advantage of geometry.

Like others have said, these high end steels do hold a good edge a long time....that razor edge is inherently weak compared to the working edge.
Click to expand...
Actually, the more accute angle holds a working edge longer than the more obtuse edge. Yeah, I know it sounds "backwards" ...

Mr. @Larrin, (of Steel Nerds) one of our resident steel experts, has said this in a few of his articles after CARTA testing.

I've found over the years/decades my knives with a 20 degree inclusive (10 DPS) don't need resharpened as often as those with a 25 degree inclusive (12.5 DPS) and 30 degree inclusive (15 DPS) edge.

If the knife comes with an edge greater than 15 DPS, I thin and reprofile the edge before using it to either 10 DPS or 15 DPS, depending on what the knife will be used for.

Sole Exception:
A Grohmann 350R Jack Knife that had/has an 40 DPS (80degree inclusive!!!) factory edge.
I gave it away before thinning and reprofiling the edge. I don't have a belt grinder.

The paperwork that came with it said to hold the blade 40 degrees to the stone when "sharpening". An email to Grohmann confirmed the unuseable obtuse 80 degree edge angle.
Grohmann didn't say why they use such an unuseable obtuse edge (that can't cut a stray/wild thread, or sharpen a pencil) on a small pocketknife.
 
afishhunter said:
Actually, the more accute angle holds a working edge longer than the more obtuse edge. Yeah, I know it sounds "backwards" ...

Mr. @Larrin, (of Steel Nerds) one of our resident steel experts, has said this in a few of his articles after CARTA testing.

I've found over the years/decades my knives with a 20 degree inclusive (10 DPS) don't need resharpened as often as those with a 25 degree inclusive (12.5 DPS) and 30 degree inclusive (15 DPS) edge.

If the knife comes with an edge greater than 15 DPS, I thin and reprofile the edge before using it to either 10 DPS or 15 DPS, depending on what the knife will be used for.

Sole Exception:
A Grohmann 350R Jack Knife that had/has an 40 DPS (80degree inclusive!!!) factory edge.
I gave it away before thinning and reprofiling the edge. I don't have a belt grinder.

The paperwork that came with it said to hold the blade 40 degrees to the stone when "sharpening". An email to Grohmann confirmed the unuseable obtuse 80 degree edge angle.
Grohmann didn't say why they use such an unuseable obtuse edge (that can't cut a stray/wild thread, or sharpen a pencil) on a small pocketknife.
Click to expand...

Their website says 20-30 degrees per side, so somebody figured it out:
https://www.grohmannknives.com/index.php/customer-service/sharpening
 
Ditto what most have said already about a working edge versus polished edge. I've found going above 600 grit in general doesn't add any longevity to the life of a cutting edge. I find it's more about how long the "teeth" on the edge stick around than the exact angle of the bevel or how shiny it looks.
Just watched an interesting video about a combo style sharpening method that seems relevant. In particular, check out the diagram at about 1:30 in:
 
High-wear steels are not a myth. Some steels really do hold an edge a lot longer than more pedestrian steels.

CPM M4 has very good edge retention.

My guess is that you're not fully deburring the apex. A burr can be very sharp, but it won't last long.

Personally, I think polished, refined edges do cut better and last longer than coarse edges. But coarse edges do tear and rip better.
 
Try a courser edge 600-1200 and if you are not happy try the 6000 again, but make sure to kill the apex each time you sharpen as there may be fatigued steel near the apex from factory grinding. Outpost76 had a bench made M4 that got good edge retention only after the 14th edge if I recall. Let us know what you figure out.
 
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