Getting back a working edge on 3V

K

KC8QVO

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Apr 7, 2011
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162
I have been using a 3V blade for several months now for every day carry and it needs touched up. I have asked about sharpening 3V here before, but I have a different goal - I just want a good working edge. I'm not after refining this edge much. Where the blade was yesterday was it would tear an envelope, not slice it open. I gave it a run on my paper wheel (slotted one only) and now it will slice a bit better, but it is still not a good working edge. Should I just spend a lot more time whacking away at it on the paper wheel?

Any ideas?

The edge was factory until last night. I didn't want to touch the convex edge too much, I did with my other 3V blade so this one I wanted to keep stock.

I'm not after shaving sharp, I just want the darn knife to work. I mostly use it cutting open boxes, envelopes, and other packages, as well as some wire stripping.
 
3V will sharpen just like any other steel, it's just a lot tougher than most. If you're used to sharpening less wear-resistant steels (A2, AUS-8, etc) you'll be surprised how much time it takes to get 3V into shape. Just keep at it, and it will sharpen up just fine, no worries. :)
 
If you are sharpening a CPM-3V with a convex edge on a paper wheel you are essentially going from convex to concave and are most likely contacting more shoulder than you are edge. If you want to use the slotted paper wheel to just touch up the edge, I would suggest that you use the sharpie trick to make sure you are contacting the edge. If you want to keep the convex I would suggest using strops, wet/dry papers or a belt sander.
 
I'll have to respectfully disagree about the convex to concave remark above. The wheels will give a more V bevel than a convex or concave unless you deliberately try to grind your blade that way. The contact area on the wheel is very small and will not "naturally" grind anything other than a V grind. Maybe if the diameter of the wheel were one or two inches then you might get a concave grind. But being 8 inches or 10 inches in diameter, the contact area is very small and geometrically not round acting to the grind. You might grind a concave grind with a piece of wood or soft material, but the blade steel is too rigid to "bend" around the wheel diameter, resulting in anything other than an effective flat grinding surface to the blade. Much more rigid and flat than you will get with a belt, unless it has a substantial platen attached.

Blessings,

Omar
 
I have paper wheels and understand how you can touch up an edge without substantially altering the convex edge grind, but wheels are round and it's still concave even if slightly so. That is why I mentioned the Sharpie trick when using the wheel to avoid hitting the shoulders which I presumed to be "likely" after reading the original post and his comment about going too far and altering the original grind on his other 3V. I like paper wheels, but they simply aren't the best means to maintain a convex edge.
 
Well I spent some quality time with the blade this evening and I think I got the edge back OK. I worked on another knife also. The 3V blade had a tip that was messed up from when I got it, the point was never developed for some reason. So I used some of my Edge Pro stones on the table with some non-slip padding to hand form the tip of the blade. I didn't do too bad of a job, but I'm also not real impressed with it either. There is a point on the blade now but the convex'ness isn't uniform with the rest of the blade.

When running the blade on the paper wheel I rocked it to maintain the convex edge as opposed to the flat grind. The paper wheel puts a heck of a polish on the 3V. The stock edge (and face of the blade) is quite a matte finish. After the run on the paper wheel it's almost like a mirror (rougher than softer steels like my 1095 blades and swiss stainless Victrinox uses, but still quite shiny).

Does anyone have any idea what grit level Bark River uses to finish their 3V blades? The one I have been working with is a Necker (the small one).
 
Good for you, man.

I'm not aware of BRKT finishing CPM-3V blades different than any of their other steels and unless things have changed in recent years it is with a 400 grit belt followed by polishing on a 320 grit stitched buffer at 3600 rpm then finished on a 600 grit stitched muslin buff at 1800 rpm. The edge I believe they finish on a 15 micron slack belt. The compounds they sell and recommend for maintaining the convex edge are said to be 3000 grit (Black), 6000 grit (Green) and 12,000 grit (White), but like most compound grit rating claims they are really anybody's guess because they are based upon average particle size and don't state the standards for determining the grit rating.
 
Have you tried diamond hones (diamond is the hardest substance known, other than politicians' skulls). Today's high-carbide steels respond best to diamond abrasives, in my experience.
 
Good recommendation for using diamond. I reprofiled my 3V Koster using my Lansky and diamond hones. It took a while but worked very well.
 
Alberta Ed said:
Have you tried diamond hones (diamond is the hardest substance known, other than politicians' skulls). Today's high-carbide steels respond best to diamond abrasives, in my experience.
Click to expand...
I'll second this one. On both substances. ;) I have the same knife, and it touches up very quickly on my DMT's. I should say, I just grind it into a V bevel, I'm not real fond of convex edges. Once I set the edge bevel, it resharpens very quickly.
 
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