Does a convex grind have a bevel? If not... how do I sharpen correctly?

[biogon]

Ok...

Well.

So if you saw my Bravo-1 thread, I attacked a bunch of nasty things with my Bravo-1. (Dust and sand-laden cardboard boxes.)

By the end, the edge was pretty much crap.

So... I took my 600 grit sandpaper, laid it down flat on a squishy surface (CD holder case... pleather plus some cushioning material), pushed down, and made some passes spine-first.

Now it's sharper. Passably sharp... nowhere near my normal v-beveled knives, though. It at least cuts paper, but only on a draw stroke, and not on a push.

I also notice it's developed what looks like a visible bevel line -- not a straight one, but that glistening line along the edge that says to you, on a normal sharpening job, that you need to keep grinding because you haven't removed enough metal to get to the edge and to raise a burr.

(Speaking of which, I noticed that no matter how much I sharpened, I could not raise a burr. Can you get one with this method?)

It certainly didn't have a bevel line from the factory.

If it's not supposed to have one... how do I sharpen it out? I assume it was due to having too high a sharpening angle?

If that bevel is ok, what do I need to do to get it shaving/scary push sharp?

Also, I've tried stropping, but it seems to only get duller.

Thanks!

-j

 

[Jeff Clark]

Ask yourself, "How does my honing pad know that I want an acute cutting edge?" or "How does my honing pad know to produce an acute cutting edge?"

The answer is, it don't know squat. You need to select a pad and use it in a way that produces an acute cutting edge. You need to know what you want, select honing materials appropriately, and guide the blade during the process.

It sounds like you picked a pad that is too soft and you applied too much pressure. The pad doesn't know what you are trying to do. Being a compliant material it compliantly wrapped around your blade including around the edge. This situation is most severe with soft pads or even firm pads if you apply hard pressure. You are creating a rather obtuse final edge where the pad is trying to round off the apex of your edge. You might hope that the pad will just conform to the original blade contour, but since some of the blade material is already gone the pad doesn't have guidance to reconstruct the original bevel.

You need a stiffer pad. Try something like a 50-sheet pad of paper. For a really acute finished edge you might want to cover the pad with something like photo paper or plastic view graph material. A stiffer pad will remain rather flat and not wrap around the edge. You will get a convex bevel that is relatively flat and will approximately match the angle at which you are honing. You will dictate the angle that you want rather than leaving it up to the imagination of the pad. You still want to use rather light pressure.

You also need to use rather fine grit abrasives to get as fine an edge as you have gotten using other hones. The 600 grit paper has tall grit particles compared to a normal hone. It is sort of like a very new hone with tall lumpy particles. Try getting some 1000 grit and 1500 grit Wet or Dry paper from the automotive section of your hardware/department store.

 

[biogon]

Jeff,

Thank you so much for your help.

I tried your advice with at least shifting to a stiffer pad with a rigid liner and it seems to be minimizing my 'bevel' so far and getting a sharper edge.

It still isn't perfect, but it has been surprisingly difficult to find the 1000-1500 grit papers around here (Home Depot has pushed out all the Mom and Pop hardware stores in this area, sadly -- and it only carries up to 400 grit (!), which is why I thought to strop.)

I'll see if I can't bum some 1500 grit off an auto repair store or something!

It took me a year of practice and springing for an EdgePro to get a normal v-bevel edge I was happy with, so I'm fearful I'll sharpen away a quarter of my Bark River before I can get it sharp!

Thanks again,

-j

 

[Sword and Shield]

Car parts places normally have up to 2000 grit, so you should be fine. I've convexed pretty much all of my EDCs, and a 1000+ grit tends to work best.

Just use a light touch and a stiff pad (I use a mousepad, but a very light touch, and I can dry-shave with mine).