How fine is fine enough?

R

Rustbear

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Aug 10, 2011
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Hey all. As many of you have noticed, there are some very fine grit sharpening stones on the market. It seems to me, that some of these hyper fine grits are a bit overkill. So, how fine is fine enough? I am intrested about experience more than studies and theories.
 
it just depends on how smooth you what that edge. there are even arguments on how low of a micron to use for stroping compounds.
 
What's overkill? Anything over 600 grit...1,000 grit....10,000 grit?

It's like saying a hammer swings way too easy or a screwdriver that never strips heads....a knife that is too sharp.:eek:
 
the question really is at what point do you need to give up on the stones and move to a strop. I've got a 8000 grit diamond stone that I love, but I find if I skip it and strop it really doesnt matter.
 
The finer the edge the longer it will last. A 10,000 grit edge stropped after each use will last you for a few months or even a year. If you take care of an edge, it will take care of you :)

PS look up the youtube video "sharpening a knife at camp" made by ray mears... one of the best how to sharpening vids available!
 
If you're going to be shaving with it, then you want that edge as fine as you can possibly get it. For utility use, generally speaking, you want about the lowest grit edge that will do what you need doing. There are plenty of good threads on this topic in the Maintenance subforum, and plenty of folks have done tests that indicate for hard-use longevity your edge needs some tooth - 400-600 grit. For every task there's going to be a perfect edge grind, bevel, etc - no such thing as a "perfect edge", only the perfect edge for what specifically is being cut.

In terms of actual experience, at work I've had edges that were literally hair-whittling fail to pushcut newsprint in a week or less while their less sexy coarse edged cousins survived in the same environment for a month or more. Then again, the rougher edges could only cut newsprint with a drawcut, even fresh off the stone, so it all comes down to intended use.
 
im using dmt stones down to 3 micron and then i strop on horsehide with no compound.. seems to be perfect for EDC
 
Depends on a lot of factors. For most uses 400 - 1500 grit is fine. I enjoy hand sharpening so I will often hone down to .5 micron.
 
Depends on use.

For wood carving, most will insist on sub-micron polish compounds and have pretty good reason for it.

For cutting seat belts, some will prefer a fairly coarse edge and have pretty good reason for it.

For stabbing car hoods...it probably does not matter.
 
I usually strop with pink strachless buffing compound, does anybody know what grit this is I cant find it anywhere.
 
Rustbear said:
Hey all. As many of you have noticed, there are some very fine grit sharpening stones on the market. It seems to me, that some of these hyper fine grits are a bit overkill. So, how fine is fine enough? I am intrested about experience more than studies and theories.
Click to expand...

First, I'd like to know why super fine grit stones are overkill?
 
When I feel like it I sharpen all the way down to DMT extra-extra fine, then strop with green compound. If I feel lazy and just want a usable working edge, DMT fine (25 micron / 600 mesh) is good enough. I think this is the standard factory edge.
 
There are so many variables that it's really hard to say.

I personally like something in the 16 Micron range. (Semi Polished)
 
unit said:
Depends on use.

For wood carving, most will insist on sub-micron polish compounds and have pretty good reason for it.

For cutting seat belts, some will prefer a fairly coarse edge and have pretty good reason for it.

For stabbing car hoods...it probably does not matter.
Click to expand...

^ +1. the materials being cut should determine the edge finish and angle.
 
Tony8179 said:
First, I'd like to know why super fine grit stones are overkill?
Click to expand...
For general utility finer edges aren't optimal. I've noticed that a lower grit is better at day to day tasks like cutting rope where a fine edge is better at wood work. My experience has shown the theories to be true. Fine edge for push cutting and a "rough" edge for slicing. Where to stop is preference and will be based on what kind of cutting you do.

Most of my cutting is push cuts so I generally have them at about 1000 grit with a stropping. I've noticed that when cutting plastic banding at work this fine of a grit doesn't work as well as when I use a new knife at about 100-300 grit.
 
I just finished reprofiling the edge on my 0551 with a 45 micron, 325 mesh coarse DMT stone, and I must say that I am impressed with how sharp I got it just going to that point. I may let it sit at that degree of coarseness for a while to determine if that works better for me in my day to day use.

Though I still love a Sexy Mirror Polished edge.
 
I'll generally go up to 8000 grit, then strop with either diamond paste or chromium oxide compound. If I'm feeling lazy or I want a coarser edge, I'll stop at 1000 grit and strop. Either will work for just about any task, it's just a matter of preference.
 
From what i've learned over the years is that in general pocketknives benefit the most from a somewhat toothy edge.
A: because most work with these type of knives involves slicing & sawing motions, not push cutting, and B: most pocket knives people actually carry are made from softer steels which can be easily kept sharp by the end user, but are unable to support a polished edge for prolonged periods.

Best general recipe i have found for this class of knives is first to bring the edge down to around 30 degrees inclusive to get a better edge geometry as most are way too thick, and then give that edge a 600 grit finish.
Depending on how much bite the customer wants i then remove the burr with a 15 micron, 6 micron, or 3 micron diamond paste loaded leather strop which also gives it a convex microbevel which strengthens the apex.

But there are also the owners wishes to take into account.
A knife like the XM-18 i recently sharpened is as you know quite expensive and while absolutely up to it, most don't see too much hard use.
So while a toothy edge would still be perfectly suitable, a refined (semi-) mirror polished edge involving quite a lot of manual labour can be seen as simply more fitting for knives in this price class (and up), like aftermarket racing tires on a Mercedes.
A beneficiary side effect is that because most of these blades are made from powdered steels filled with very wear resistant but comparatively large carbides and a resulting lower edge stability, polishing of course helps to boost that stability.
So when the owner wants to use his expensive knife he still can, knowing that the edge will perform at it's best, and will also be looking good doing so.

Best general recipe i have found for this class of knives is to go through various steps to at least 6 to 3 micron to get good looks while still preserving quite a lot of bite.
Bringing down the edge angle is only done on specific customer request to preserve as much of the original looks of the blade as possible.
The owner can then easily keep it sharp with a diamond paste loaded leather strop with the same grit, or finer if he wishes to do so.
 
I typically go for 2-3 microns, which is just 5 passes per side on a 1200MX belt on my WorkSharp. But now that they've told me not to trim the corn at work, I find myself ordering more strops and fully committing to a 0.25 micron finish. I'll be buggered if I can tell a difference in sharpness, but it would take about a year or so before my edges dull enough to the point where I can't slice paper, given my utter lack of use with my knives. Though that's assuming I don't accidentally hit metal while cutting some cardboard. It's a real pain trying to sharpen out a chip out of CTS-20CP and similar steels.
 
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