Sharpening input of Spyderco Military S30V

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augostos

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Sep 15, 2011
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Hello!

I would appreciate some input about my sharpening of Spyderco Military S30V steel blade.

I use fine diamond pad and a Lansky fine ceramic rod for freehand sharpening.

Yesterday I was able to sharpen a carbon steel kitchen knife (diamond pad+ceramic rod) and a Emerson CQC7 (ceramic rod only) to a shaving sharp condition.

But my Military gives me hard time. Let me describe what I get, maybe you can direct me to appropriate procedures.

After I sharpen the Military on diamond pad, it can barely shave my arm hair, really barely... When trying to cut newspaper sheet, it cuts some slices well, but after that the sharpness deteriorate really fast, it starts to catch the newspaper paper. As to regular printer paper, it slices that one more or less nicely. Anyways, when comparing it to my other sharpened knives, I'm not satisfied with the results...

I tried to finalize the job with ceramic rod, but it doesn't help. And at the end of sharpening, I try to do it lightly to remove any burr.

So, the results a so-so and not consistent. What can I do? Why is it the first cuts are nice, but afterwards the edge gets bad so abruptly?

Maybe I need to change something, or pay attention to some particular characteristics?

Thank you very much for your help and tips.
 
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Hello !

It sounds to me that you got a wire edge which breaks after few cuts leaving a crude apex .
Try to get rid of this by either stropping on cardboard, slicing endgrain hardwood then reform the apex with the slightest pressure you can to avoid any burrs .
Keep in mind spydie's s30v is notorious to form stubborn burrs and ceramics exacerbate this effect and finally, powerful lighting really helps when chasing burrs...
 
Burrs and using too much pressure when sharpening. The pressure causes the burrs and will prevent you from attaining a sharp edge. If you use a light touch the burrs will reduce in size and the edge will be much sharper. S30V can take some time to sharpen so don't give up early.
 
Sounds like your Free Handing ?

Then your most likely it is your style.
Your are getting different angles.
 
As has been mentioned, it sounds like there's a burr or wire edge that's breaking away, at least. Another factor that might also be contributing to the poor cutting performance could be wide edge geometry (angle). If the angle is pretty wide, such as 40° inclusive or wider, the edge will be noticeably blunt after the burr breaks away. Cutting performance gets noticeably better when the edge angle is taken down to 30° inclusive (15° per side) or lower, and will also be a little more forgiving of a less-than-perfect apex. Inconsistent angle control might also be rounding off the apex of the edge a bit.

I'd first focus on using your diamond hone only; thin the edge angle if it's relatively wide (might consider picking up a Coarse diamond for this). Then refine it as much as you can on the Fine diamond, decreasing pressure as you go, and avoiding the ceramic for now. The edge coming off the fine diamond hone should be plenty sharp to cut well, even excellently. S30V really responds well to a fine diamond grit, or EF. Ceramics can undo a lot of progress made, if the pressure used with them is just a little too heavy, or if angle control is inconsistent.


David
 
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Thank you very much for your advices!

So, finally, I could make the edge hair shaving sharp. Although mostly at 2/3rds of the blade from the tip.

This is my method:
-- I tried to reprofile a little so the angle will be sharper at the edge.
-- I sharpened the edge with fine diamond pad, maybe 600-800 grits.
-- I tried to cut hardwood with that blade, so all that wire edge will be broken.
-- At last I lightly sharpened (touched) with the same diamond pad.
 
augostos said:
Thank you very much for your advices!

So, finally, I could make the edge hair shaving sharp. Although mostly at 2/3rds of the blade from the tip.

This is my method:
-- I tried to reprofile a little so the angle will be sharper at the edge.
-- I sharpened the edge with fine diamond pad, maybe 600-800 grits.
-- I tried to cut hardwood with that blade, so all that wire edge will be broken.
-- At last I lightly sharpened (touched) with the same diamond pad.
Click to expand...

The bolded part above sort of hints that the edge geometry is probably a little wide. It's very common for the edge angle to get a little wider nearer to the base of the blade (ricasso), because most blade grinds will be thicker in that portion. Even more so with the Spyderco Military, because it's tapered from the ricasso towards the tip (this is called a distal taper). Assuming the blade's grind is thicker near the base, the edge angle will be wider in that portion, in order to maintain the even width and uniform appearance of the factory edge bevels along the entire length of the blade's edge.

Since you've made progress so far, I wouldn't necessarily worry too much about undertaking the big job of thinning the edge angle more. If you do eventually want to improve the hair-shaving sharpness of the entire edge, thinning the edge angle would be the best way to start that process. All the rest is just about getting better at maintaining a consistent angle while sharpening, and making good use of pressure (gradually lightening it as the edge becomes more refined). I'd still focus on making the best use of your diamond hone right now, and don't worry about the ceramic. Ceramics can do great things, but it's very important to give them a good foundation to start with (creating good edges with your diamond), and then use them very carefully to enhance it. Ceramics are at their very best when it takes a minimum of feather-light strokes to really make an already-good edge pop.


David
 
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