How sharp should a convex edge be before you strop it with compound?

J

JayTee705

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Sep 27, 2006
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I just bought my first convex grind knife from a reputable manufacturer.

I am unimpressed with its out of the box sharpness.

My question: how sharp should it be before you strop it with black, then green compound?

I'm willing to strop it if I can get the desired results. If I have to first do a mousepad and various wet/dry grits--or something similar--then I'll consider returning it. The knife is certainly not scary sharp and it's not really even shaving sharp. Even paper push cuts can be iffy, depending where you are on the edge

My issue is that I don't really know where a strop and black/green compound fall on the abrasive side of things and what they can actually accomplish given time. If it was a regular V grind, I'd have some idea of what grit to use and how much I could expect to accomplish.

Thanks!
 
Even Sebenzas don't always come sharp, and those are the only convex knives I've bought.

If I were to guess, the edge is probably a little steep, and would benefit from a little thinning. If you don't want to bother with that, and I couldn't blame you, then I'm sure you can get it sharp with compound.

The grit in black compound is usually 3-5 micron, so it won't work for much besides finish work.
 
myt132-cu said:
Even Sebenzas don't always come sharp, and those are the only convex knives I've bought.

If I were to guess, the edge is probably a little steep, and would benefit from a little thinning. If you don't want to bother with that, and I couldn't blame you, then I'm sure you can get it sharp with compound.

The grit in black compound is usually 3-5 micron, so it won't work for much besides finish work.
Click to expand...

Not sure where you got your Sebenza, but I've got three of 'em. NONE of them are convexed. Unless CR Knives has done something radical, they're still made with hollow grind blade, with V-grind at the edge. And plenty sharp too.

You might want to take a peek at post #1 (and accompanying photos) in this thread ('Chris Reeve Knives' in the Mfrs. forum):

http://www.bladeforums.com/forums/showthread.php?t=484936
 
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JayTee705 said:
I just bought my first convex grind knife from a reputable manufacturer.

I am unimpressed with its out of the box sharpness.

My question: how sharp should it be before you strop it with black, then green compound?

I'm willing to strop it if I can get the desired results. If I have to first do a mousepad and various wet/dry grits--or something similar--then I'll consider returning it. The knife is certainly not scary sharp and it's not really even shaving sharp. Even paper push cuts can be iffy, depending where you are on the edge

My issue is that I don't really know where a strop and black/green compound fall on the abrasive side of things and what they can actually accomplish given time. If it was a regular V grind, I'd have some idea of what grit to use and how much I could expect to accomplish.

Thanks!
Click to expand...

If it's cutting paper at least a little bit, you might just try some careful stropping on bare leather to start. There may just be a little bit of a burr or wire edge getting in the way. Stropping on bare leather, if done carefully (i.e., not too steep), won't do any harm to the existing edge (which is a good thing if you decide to send it back to the maker) and it might show you if there is a burr. If so, the stropping should at least IMPROVE the cutting of paper first, then if you're lucky, you might start to see a little shaving capability. If you do see a change in the right direction, then you might try the stropping with some compound. Again, as long as it's done carefully, there's not much risk that you'll damage it if you do choose to let the maker have it back.

If you have a good magnifier (at least 5X or greater), you might take a close look at the edge to see if it's noticeably rounded or otherwise imperfect. Might tell you a lot about how close it is (or isn't) to being sharp.
 
Your knife is what we like to call in scientific terms, Dull.


Start with 220 or 320 and form your edge then continue to work up through the grits, 400, 600, 800, 1000, 1500, then 2000grit. After 2k your edge should be a hazy mirror and be very sharp/hair poppin sharp. If not don't strop because its simply not ready for that stage yet. Before any stropping is done the edge should be nearly burr free and have razor like sharpness, otherwise your just wasting your time.



FYI, I know everyone likes it but cutting paper is a rather poor way to test sharpness and dulls your knife in the process.
 
Obsessed with Edges said:
Not sure where you got your Sebenza, but I've got three of 'em. NONE of them are convexed. Unless CR Knives has done something radical, they're still made with hollow grind blade, with V-grind at the edge. And plenty sharp too.

You might want to take a peek at post #1 (and accompanying photos) in this thread ('Chris Reeve Knives' in the Mfrs. forum):

http://www.bladeforums.com/forums/showthread.php?t=484936
Click to expand...


The OP's question was "How sharp should a convex edge be..."

I'm not sure that the blade grind makes a difference. He was asking about a convex edge.

I've never seen, first hand, a knife with a convex grind. I think Bark Rivers are, or maybe some of them are, but I know nothing about convex primary grinds, nor would I be interested in any.

I am well aware that almost all Sebenzas are hollow ground, although there may be some early ones that are flat ground. I know that both of mine are hollow ground, but that's certainly not something that can be confused.

I also know that Sebenza's edges are ground to shape on a belt and polished on a hard felt wheel using aggressive compound. That is not how V edges are formed. In fact, I don't think you can manage to get a v edge that way no matter how hard you try.

If you have an unsharpened Sebenza, put a flat edge on the edge bevel at the tip where it is widest and easiest to see. Does it sit there nice and flat? Probably not even close. I know mine weren't. Mine weren't very sharp by my definition either, but that's something that I could not possibly care less about. Factory edges only have to last me until I get to my stones.

It's no big deal. Trust me, I make mistakes all the time.
 
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I guess we aren't seeing something eye to eye. If you understand that you are putting a little convex on a blade stropping on leather, then I don't understand how you can think that you can get a v edge off a buffer. In my mind that's just not possible.
 
myt132-cu said:
I guess we aren't seeing something eye to eye. If you understand that you are putting a little convex on a blade stropping on leather, then I don't understand how you can think that you can get a v edge off a buffer. In my mind that's just not possible.
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Because they are not buffing they are de-burring and not enough to convex the edge. When I started with that knife the angle was straight enough to "lock" the bevel to the stone. You will also notice in the pics of the factory edge the buffing only effected the shape of the shoulder of the bevel.


It's not enough convex to call it convex in either case.
 
Thanks for the replies.

To be clear, I was talking about a convex grind blade--like a Bark River Gunny or a Fallkniven WM1, etc.

I don't like to brand bash, so that's why I'm not being more specific. It's not a CRK Sebenza in any case.

I've never sharpened a convex grind knife. That's why I had hope it would come properly sharp out of the box so I could see what it's supposed to be like.

Anyhow, I'm gathering some wet/dry grits as well as a strop, so I'll have at it soon enough.

On one hand, complaining about a new knife not being sharp is sort of like complaining about a new car only coming with half a tank. You have to take care of that soon enough. But that's an imperfect analogy. I'm just going to be sure to ask my internet retailer the next time to take a look before shipping...
 
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