How much "refinement" is really needed?

[Noctis3880]

I was a little pressed for time trying to sharpen up two knives(Spyderco Moran Featherweight in VG-10 and Benchmade 581 in M390), as I was running my Worksharp about 15 minutes already raising a burr and going through the grits and didn't want to risk burning out the motor, but didn't want to wait an hour before continuing. So I went up to 320MX belt for both knives, cut into a wood piece several times to remove the burr, and skipped straight to my 12000 AO belt(2-3 microns). The result was actually surprising. I was able to pop my leg hairs with the resulting edge, something which I would get after going through the 360, 400, 600, 800, and 1200MX belts in between those two. Granted the edge wasn't as polished, but it did kind of make me feel like I've been wasting my time going through all those belts.

So I'm kind of surprised that actual "refinement" of the edge after raising a burr isn't all that time consuming. And I guess I shouldn't be that surprised that the paper wheels can get such an edge with just 2 grits(though I still prefer a larger grit range of my belts to remove more or less metal depending on my needs).

But I suppose when you consider that if the edge already meets at a single point(a raised and removed burr), actually refining the edge doesn't take that long unless there's some serious teeth on the edge. Though I'm really curious to know if this would extend to stropping as well. Some people like to promote stropping for over 10 minutes, but now it seems like even going to sub-micron abrasives, it would maybe take no more than 20 strokes total to refine an edge.

I'll have to give it a shot when I get some more strops in:thumbup:.

 

[Ben Dover]

I would say that it depends on what your preferences are.

Personally, I like to polish most of my better knives to .125 micron with CBN on a balsa strop.

Knives of lower grade steels, or those with very large carbides, of which I have very few, are sometines left at 2K to 3k, due to my belief that those particular steels are not worthy of the additional effort.

Unfortunately, one of my old favorites, D-2 has the large carbides, and I seldom hone them past 2K and a few strokes on a bare strop. (I'm not quite sure that the stropping adds anything worthwhile, but it does gives me a warm feeling! )

 

[Obsessed with Edges]

As with all things us sharpening nuts like to do, I'll simply ask "What's NEED got to do with it?"

Kidding aside, the one big thing I've come to like about more refined edges is, the more refined it becomes, the less it needs (grit-wise) to touch it up again. A highly refined edge responds very positively to light stropping on almost any surface (bare leather, paper, cardboard, wood, jeans, etc.). That translates to very easy maintenance, no matter where you happen to be, with or without the 'proper tools'. A more refined edge, so long as it's not allowed to go completely blunt again, can be touched up with virtually no additional metal removed. And on convex edges, the more polished the convex becomes, the slicker & more effortless the cutting gets.

I do agree, so long as the very cutting edge itself is pure & clean (burrs & wires completely removed), the degree of 'refinement' of the edge itself doesn't necessarily make a lot of difference in most situations. But I have noticed a much bigger difference in how the 'shoulders' of the bevel come into play, and how a rough or polished shoulder on the bevel will make drastically different changes in how a blade slices through thicker material. When the shoulders of the bevel are 'wedging' themselves into the material being cut, it's all about friction at that point. Smoother, more polished shoulders make for a lot less of it.

(Edit: I do spend considerable time initially, in getting a very polished edge & bevel. But the trade-off comes after that, as the upkeep is virtually effortless from there on. I think that is what 'refinement' is all about. Taking the finish further at the start, means less work will be needed later.)

This is why I like my edges (& bevels) more refined.

 

[stitchawl]

I've been saying all along that stropping for 30 minutes is simply NOT what stropping is about.

By the time I get to strops, I need no more than 20-30 strokes to accomplish the goal of that particular compound. Same with using a bare strop... 20-30 strokes is more than enough.

Have you ever seen a barber give more?


Stitchawl

 

[GlennS1956]

...stropping for 30 minutes is simply NOT what stropping is about.

That's the lesson my Digital Microscope taught me the first time I used it as a sharpening aid. For 40 years I have been sharpening my knives way too much, and removing way too much metal. I also learned that stropping is a lot more effective than I thought it was. And stropping actually does remove metal, instead of simply straightening and polishing it.

 

[Ben Dover]

In my experience, the amount ot time and strokes required to accomplish your objective on the strop is a direct function of how well the blade was prepared before being taken to the strop.

 

[HeavyHanded]

I've been taking a closer look at my edges now that I have access to a metallurgical microscope. I'm amazed at the level of refinement that occurs even at relatively low grit values if one is paying attention. At 400 grit if one strops with an appropriately sized larger grit, the cutting edge though lacking uniformity will display a surprising amount of refinement at the apex - nearly the same as a 2000 grit edge when viewed at high resolution. That the apex happens to move about quite a bit is the primary reason for differing cut characteristics (or so it appears). There's also a huge difference in the grind patterns left by different media and thats something that can be felt in use also. How much stropping is needed/wanted will depend on a lot of factors - the desired cutting characteristics, how defined the grind pattern is, what grit you're stropping with, how many stone progressions you have done, how hard/soft he backing is, how much pressure is used etc. As with all things sharpening related, there's no one answer - I recall reading on a straight razor forum one gentleman said he sharpens his straights till they can just shave arm hair and then they get stropped, as much as 50-80 times on a loaded strop and the same on the plain leather, at which point they'll pass a HHT.

 

[Noctis3880]

In my experience, the amount ot time and strokes required to accomplish your objective on the strop is a direct function of how well the blade was prepared before being taken to the strop.

I used to think that meant going through all my belts in progression to get as any grits as I can in between prior to the strop. But now I recall stropping my Moran Featherweight with the factory edge to great effect, and IIRC most factory edges are put on with a coarse grit wheel and a polishing wheel. Which sounds a bit like the paper wheel setup.

I figure this time around I can go with 240MX, 320MX, 12000 AO, then strop with 1, 0.5, 0.25 micron. Before I would go through all the belts(60, 150, 180, 240. 320, 360, 400, 600, 800, 1200MX, 12000AO) and be too tired after to bother with strops, and I would still end up with an edge that pops a leg hair here and there.

 

[Ankerson]

No more than it takes to get the job done is the basic answer.

Depends on the use intended for the knife.

 

[Noctis3880]

No more than it takes to get the job done is the basic answer.

Depends on the use intended for the knife.

Again this is less about coarse vs fine and more about how much "in-between" grits you really need to get the ultimate refined edge.

I just finished my Spyderco Moran Featherweight from 60MX(60 micron) to 240MX(about 25 micron) to 320MX(11-12 micron) to 12000AO(2-3 micron), a 1, 0.5, and 0.25 micron diamond loaded strops(10 strokes per side each) and finished off on bare horse butt leather. The resulting edge could cut free-hanging hair and is about as sharp as what you put on my Manix 2 in CTS-XHP:thumbup:. My leg also has bald spots from today's fun.

I'll be off to test out this new edge on a mango.

 

[P2P]

When it comes to refinement with strop with compound (green), the amount of time varies for me with each steel. 154 cm maybe 20 strokes each side. S30V I estimate around 100 strokes each side.

 

[P2P]

By the way for some real fun try scraping all the compound of your strop. That will show you how effectively those compounds are on metal.

WARNING- You will have to start a whole new edge with coarse stones!!!

 

[Noctis3880]

When it comes to refinement with strop with compound (green), the amount of time varies for me with each steel. 154 cm maybe 20 strokes each side. S30V I estimate around 100 strokes each side.

This is why I prefer diamond spray. Particularly the hand american ones, those dry up real fast. The one I got from japaneseknifesharpening was the Dupont version, which left my strop completely soaked in. I used a hair dryer to get it dry, but I can tell it completely ruined the leather.

 

[unit]

There is "need" and there is "want". Sometimes what you want is also what you need.

There are also countless variables regarding steel, hardness, intended use, and desired appearance. There will be a lot of answers.

 

[Ben Dover]

Again this is less about coarse vs fine and more about how much "in-between" grits you really need to get the ultimate refined edge.

I just finished my Spyderco Moran Featherweight from 60MX(60 micron) to 240MX(about 25 micron) to 320MX(11-12 micron) to 12000AO(2-3 micron), a 1, 0.5, and 0.25 micron diamond loaded strops(10 strokes per side each) and finished off on bare horse butt leather. The resulting edge could cut free-hanging hair and is about as sharp as what you put on my Manix 2 in CTS-XHP:thumbup:. My leg also has bald spots from today's fun.

I'll be off to test out this new edge on a mango.

Whatever works well for you, and provides the edge that you desire is the correct method for you.

 

[HeavyHanded]

Here's a few pics that I thought might be an interesting add to the thread. The first is at 160x, the second at 640x prior to stropping, the third is after about ten passes/side on some AlumOx stropping compound. You can clearly see a few things, how quickly the perpendicular scratch is being erased from the bevel - scratch is from the Kydex sheath (I should get a leather one for it) and wasn't visible at all to the naked eye. For reference the focal depth is less than the depth of a grind scratch and a human hair takes up nearly half of the image area at 640x. Another is the pit at lower right from a piece of loose grit impacting into a grind trough - the crater is much reduced in the second shot and slowly disappearing - can also clearly see how some of the debris and "micro chipping" along the edge are disappearing as well. I gave it another dozen or so passes on the strop after the second pic but didn't take another shot because the "reference" scratch was completely gone by then and I couldn't find the same spot on the the bevel - which continued to show a reduction in depth at the apex. Knife is 1095, stone is a King 6000 grit waterstone. This edge can just tree-top leg hair after raising and removing the burr twice and stropping 20 or so times.

 

[David Martin]

This is great info. DM