Questions on edges.

[Indianbladenoob]

I have a few questions on edges. These may have been asked before but I beg the indulgence of those more knowledgeable than I

Here's what I do for my edges. I cheat a bit. I can't freehand so I go through the stones on a Lansky deluxe and start with the rougher stones depending on how bad the edge is. After the 1000 grit white stone, the edge is plenty sharp. Push cuts and wave cuts hanging newspaper. But it often snags. Is this because of the microserrations?

I then go directly to the strop. And green buffing compound (unknown grit) not the black emery (also unknown grit). I lay the final bevel flat on it and pull with pressure that is a smidgen over the weight of the knife. This appears to put a sort of convex microbevel on the edge and its a very cuts-when-touched kinda edge. Takes translucent slices of finger skin off if I am not careful

Is this a "coarse" edge, fine or superfine edge?
How much finer can it be taken to?
The edge on my kitchen knives seems to last longer. The BK14's 1095CV sharpened by this method hols an edge for days of kitchen use and edc at <40deg inclusive though the mirror finish on the bevel wears off.

I also use the "<" sign ahead of the edge geometry because I realized that the exact angle varies according to the width of the knife. The number is simply the whats written on the guide hole of the lansky kit. I clamp all knives in the little "lip" at the end of the lansky clamp and follow the same angle for a given knife. It seems to work. I follow <17Deg for my kitchen knives ( Japanese Santoku and reconditioned metal saw blade cleaver), <20Deg on my folders and smaller fixed blades. My chopper I freehand and strop.

Don't get me wrong, but I love freehanding and my skills are growing (however slowly). But for pure function I find that this seemingly convex microbevel edge works really well for me for kitchen work and EDC and seems to last longer than the V-edges put on it by the lansky and anything I can freehand on to a blade as of now.

What would happen if I stopped using the lansky at about 280 grit i.e. the medium stone at a uniform burr and went directly to the strop?
Either the black compound and then the green or directly to the green? I venture it will shine the blade up but will it cut better and/or last longer?

And my apologies if this is in any way repetitive.

Thanks
Vasu

 

[Obsessed with Edges]

The best way to find the answers to the 'what if' questions (such as "What if I stopped at 280 grit..."), is to try these things out, and see for yourself. There are way too many variables playing into the process, and most of them depend entirely on individual skill and technique. So, it would often be meaningless to ask someone else to accurately predict the results of your own efforts, except in cases where it's glaringly obvious something 'wrong' is going on.

I do agree, a convex edge on a blade can make it more durable.

Regarding your question about (possible) micro-serrations causing snagging, when cutting newspaper, it's more likely due to burrs on the edge. Even a fairly coarse & toothy edge can cleanly slice through paper without snagging, so long as the edge is fully apexed and properly aligned. Burrs that are folded over, to one side or the other, are what will usually 'snag' on paper.

Regarding the question of what constitutes a 'coarse', 'fine' or 'superfine' edge, I think most people here would define that according to how high one finishes in grit. In other words, how toothy or how polished the final edge will be, assuming all edges are fully apexed and pure. Well-executed 'coarse' and 'superfine' (highly polished) edges can both produce 'translucent slices' of skin taken from a fingertip,so long as all the burrs are properly cleaned up. The greater factor there, is more likely the edge angle (more easily done at more acute, thinner edge angles), regardless of the finish on the edge bevels.

 

[BluntCut MetalWorks]

David's (Obsessed with Edges) well articulated answers are thorough and helpful :thumbup:

I will repeat & add:

Here's what I do for my edges. I cheat a bit. I can't freehand so I go through the stones on a Lansky deluxe and start with the rougher stones depending on how bad the edge is. After the 1000 grit white stone, the edge is plenty sharp. Push cuts and wave cuts hanging newspaper. But it often snags. Is this because of the microserrations?

No, probably some burr.

I then go directly to the strop. And green buffing compound (unknown grit) not the black emery (also unknown grit). I lay the final bevel flat on it and pull with pressure that is a smidgen over the weight of the knife. This appears to put a sort of convex microbevel on the edge and its a very cuts-when-touched kinda edge. Takes translucent slices of finger skin off if I am not careful

Is this a "coarse" edge, fine or superfine edge?

Coarse edge with refine outline and possibly a refine apex (refined bevel faces meet at apex). Envisualize it, you'll get your very own best answer.

How much finer can it be taken to?

Peak at a refine apex. Going past that is the same as using too fine of a grit for grinding, should use black compound (SiC ~1-3um) instead before green (CrO ~0.5um).

The edge on my kitchen knives seems to last longer. The BK14's 1095CV sharpened by this method hols an edge for days of kitchen use and edc at <40deg inclusive though the mirror finish on the bevel wears off.

Too many variables at play to draw much in a comparative conclusion.

But for pure function I find that this seemingly convex microbevel edge works really well for me for kitchen work and EDC and seems to last longer than the V-edges

There aren't much data on variables at play for tools, operational and environment to draw concrete answers/reasons.

I had similar thoughts about various edge geometry before so after countless in-the-hammock edgelightenment sessions, I posted Apex Bevel Geometry http://www.bladeforums.com/forums/showthread.php/992879-Apex-Bevel-Geometry-cross-sectional

What would happen if I stopped using the lansky at about 280 grit i.e. the medium stone at a uniform burr and went directly to the strop? Either the black compound and then the green or directly to the green?

280 grit finished surface is rough - big teeth, deep scratches, stair steps ridges, etc... 280 grit = ~ 50microns, where common average apex thickness probably around 5microns (wag), so directly jump to:
a) SiC/black 3um compound - sure, refine the surface then go to 1um or 0.5um.
b) SiC/black 1um compound or Cr2O4/green 0.5um compound - Effective cutting rate is much less than 1/0.5microns because strop cut rate = pressure[abrade+lapping]) could be a waste of time and ruin your strop at the same time. Do a) first.

I venture it will shine the blade up but will it cut better and/or last longer?

nah, no 'shine/haze/mirror' without a proper grit progression; however there could be scratchy-shine. Stout toothiness won't cut better but probably last longer for coarse/rough cut. Pondering about Apex Bevel Geometry performance?

 

[Indianbladenoob]

Holy C***!
Lots to chew on.
Thanks David and bluntcut. That's a very cool post; the Apex Geometry explanation.

So the strop compound is merely cleaning off the burr and smoothing out the sides of the apex bevel near the apex as I understand it.
And from that post I gather that even at lower grits/higher microns one needs to clear the burr/wire/edge rolling to get a coarse or toothy but sharp edge. Also I can refine it on fairly high grit directly after removing the burr as long as I don't require a shiny edge.

I am going to try the method is post number seven of that thread and see what happens.

Also following that thread now



I'm gonna try it on a cheaper knife first.