How does everyone do their final sharpening?

^^ true, plus the guys that insist on a very acute,mirror edge (for the steel and application) are likely to want to apply it themselves.

Still... Occasionally I see someone remark when they receive a custom that has an incredible edge. Guess it depends on how much you want to invest in the knife.
 
vintagefan said:
A super fine edge will be destroyed to worse than a machine finished edge within the first couple uses, at least from what I've seen.
Click to expand...

I don't agree with this statement... or perhaps, misunderstand it. Do you mean fine edge or refined edge? I'll agree that an overly acute fine edge won't hold up as well but a well refined polished edge will outlast a less-than-refined edge.
 
Rick Marchand said:
I don't agree with this statement... or perhaps, misunderstand it. Do you mean fine edge or refined edge? I'll agree that an overly acute fine edge won't hold up as well but a well refined polished edge will outlast a less-than-refined edge.
Click to expand...

Sorry, refined is probably a much better word. I'm notoriously bad at getting my point across accurately.

I meant fine as fine wine. A very high quality edge.
 
You would be surprised at how long a well refined fine edge in a properly heat treated knife that has not had the edge cooked by dry abrading it will hold up in a commercial kitchen with a good chef using it. There is a difference between good geometry and a wire edge. A wire edge which is what you get when you raise a burr and then polish it will act extremely sharp for 5 or ten cuts then as it peels off or flattens you will be left with whatever geometry was behind it, which if the knife was done on a slack belt or paper wheel likely approaches 45 degrees at the apex. Proper geometry will keep cutting even after the first couple of microns at the edge have eroded until you have gotten back to where the edge cross section is 4-6 microns or thicker. Geometry cuts, steel choice and heat treatment determine for how long, dry abrasion shortens that "how long" substantially by destroying the heat treat in that first couple of microns so that they bend or wear away much faster or just do not hold up to the geometry to begin with

-Page
 
Page,

I understand what you are saying, and I agree with you. I think that the average slack/belt and paper wheel sharpening job is probably very much like you describe. I am a bit more particular about my techniques, and I feel that I get a much better result than what probably would be achieved in "normal" circumstances.

I have specific angles, pressure, and speeds I use, as well as specific abrasives. I have 5x, 10x, 40x, and 100x professional quality loupes that I use to inspect the edges during and after sharpening and testing, to monitor my results and final geometry. I have an extra hard buff that I hand load with a homemade compound containing lapidary diamond powder with a lubricating/cooling agent as the carrier (this is my version of a compound used in optics, which I found out by accident, works amazingly well for loaded stropping). I run it very slow, probably a similar SFM to someone dragging the blade across a stone quickly by hand.

I have a fairly impressive hand sharpening setup, including a wide selection of AO and diamond lapidary films down to 0.1 micron (I used to work at an optics company). While I am able to get a better result by hand finishing, I haven't found it better to the point where I feel a need to stop using my current machine-finished method, at least for working edges (meaning multiple daily uses).


I've sharpened knives for friends, family, and acquaintances for many years, and most of the knives I sharpen are either kitchen knives that get thrown in dishwashers and into the sink banging against everything, or working knives that get abused in just about every way imaginable.

At one point I was hand finishing blades for people just for that wow factor, but when you have someone bringing the same blade back every month with the edge totally obliterated, spending much more than a few minutes sharpening it starts to make very little sense. I haven't found hand finishing a significant help, with the amount of misuse inflicted on most of the knives I sharpen for people. We aren't talking wearing down a few microns, more like big chunks and chips taken out of the edge, almost every time the knives come back. Advising people to be more careful has pretty much failed at this point, unfortunately. :(

I used to sharpen almost exclusively by hand, in fact, but the amount of time it takes vs. the amount of time it takes to ruin, is what finally forced me onto the machine. Prior to my KMG, I used the slack part of the belt on my 6x48.

I think on higher end customs, very refined hand finishing is fully warranted and almost expected, but on working knives, it's still hard for me to adopt again.



edit: This reminds me of the "disposable box cutter blade" discussion I read in another thread. People are so abusive to their knives and have such little desire to maintain them, that they just buy disposable ones they can trash and throw away. I see this mentality almost every time someone brings me a blade for sharpening. Tradesmen nowadays are so used to cheap, disposable imported tools, that they've forgotten the virtues of caring lovingly for a fine tool. I think the degree/type of sharpening a blade receives relates to the user and intended use as much as the blade's design does.

I cringe when I see people nonchalantly throw a screwdriver or wrench on the ground or over their shoulder, instead of just setting it down. I see the same type of thing with the knives I sharpen. I buy good tools, and I treat/maintain them as such. I guess when someone can buy a screwdriver at HF for 10 cents, they aren't as worried about ruining the tip by chucking it at concrete for no reason.


I still do hand finish sometimes, the last was a Benchmade gold class that was an EDC, and lovingly cared for. I put a scary sharp edge on that sucker, and I'm pretty sure it's probably still very sharp.
 
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You guys get the idea. Last thing I'll mention is that, assuming the steel is cooked well, the geometry and finish should be matched to the steel type, edge stability and intended use. That's why a very well set up multi-blade traditional will have differing geometry for two or more blades on the same knife.

It can be overwhelming to discern which geometry works best as the choices are myriad, but as a point of sale, it would take your knives to a different level. This assumes that you are selling to a person that doesn't abuse his/her knife, but I believe that you can bolster the edge stability by using a little bit more of an obtuse edge while still offering a better grind than the other guy.

Just depends on how much you want to invest in each blade.

Much respect to all of you. You guys are amazing! :)
 
sunshadow said:
You would be surprised at how long a well refined fine edge in a properly heat treated knife that has not had the edge cooked by dry abrading it will hold up in a commercial kitchen with a good chef using it. There is a difference between good geometry and a wire edge. A wire edge which is what you get when you raise a burr and then polish it will act extremely sharp for 5 or ten cuts then as it peels off or flattens you will be left with whatever geometry was behind it, which if the knife was done on a slack belt or paper wheel likely approaches 45 degrees at the apex. Proper geometry will keep cutting even after the first couple of microns at the edge have eroded until you have gotten back to where the edge cross section is 4-6 microns or thicker. Geometry cuts, steel choice and heat treatment determine for how long, dry abrasion shortens that "how long" substantially by destroying the heat treat in that first couple of microns so that they bend or wear away much faster or just do not hold up to the geometry to begin with

-Page
Click to expand...

Is this expected even for "high speed steels" such as CPM-M4 which temper well above 1000F? Or perhaps the concern there has less to do with burnt edges and more to do with carbide volume and size but gives a similar result (i.e. not holding up to begin with)...?

Regarding good cutting geometry, I am finding that too much focus is placed on apex angle rather than thickness behind it. In Verhoeven's study of razor blades, 15-dps (30 degress included) seemed to be the preferred apex angle even for shaving due to durability and apex-stability issues. However what isn't discussed is that these blades were as thin as 50 microns (0.002") at the bevel shoulders, which is 10x thinner than most utility blades, a very narrow bevel followed by a very thin blade. I would be surprised if a blade sharpened to 45 degrees (inclusive) on a paper-wheel but left razor-thin at the bevel shoulders wouldn't perform nearly as well if the burr doesn't thicken the edge by simply rolling over and not flaking off. It was my understanding that this is part of the purpose of stropping after sharpening - to cut a slightly thicker apex angle and clean it off, thereby improving durability. With an edge that thin, resistance at the shoulders is minimized such that increasing resistance at the apex is less noticeable cutting rougher materials (e.g. wood, cardboard), and deep cuts encounter less binding resistance and so require less force, which can reduce apex damage from torquing or slamming into an obstacle like a cutting surface.

If dry abrasion can actually (as opposed to theoretically or for an irrelevantly short period of time on an irrelevantly short edge area) heat the apex of a blade that high, I have no doubt that cutting lengths of cardboard is more damaging, and that is "use". If the edge cannot survive such use... But I am speculating and am no metallurgist or bladesmith.
 
I set the edge bevel and finish sharpen using a Bubble Jig. Belts 120 220 400 600 making sure to maintain a wire edge throughout. At 600 I pull the edge bevel
through a set of tungsten carbide strips set with a matching angle to strip the wire edge. The wire edge is removed in one motion.
Over the last 15 years I've come to the conclusion that abrading at the same pitch each and every time is the secret to maintaining a fine edge.I prefer a flat ground edge for this reason; its easy to reproduce. I believe the convex edge is always changing because of differing pressure placed on the edge with each sharpening and is much harder to reproduce by the average sharpener.
Sharp is good however you get there.
 
I use a HF 1x30. With a 600 grit trizact belt. I flip my machine on its back, with the small wheel pointed at my chest. I put the blade in the slack area between the top of the platen and the small wheel. I keep the cheap platen on there to provide some tension. I grind my blades hard, and take my edges down to almost zero. My sharpening usually lasts maybe one pass or two on each side. I then strop with a strop stick loaded with flitz or white compound.

I understand and respect what Page is talking about, and it's interesting. However, I like this method, and it produces some very clean and extremely sharp edges.
 
Ive seen the difference between hair poping.. and hair toping sharp, I use most the methods mentioned above, and consider the end user when chosing, either way that knife is cutting news print, and has left a bald spot on my arm before it leaves the shop.
 
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