A Different Kind of Convex Sharpening Question.

J

JohnnyO

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Sep 1, 2002
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I've seen all the demos. Read all the instructions. I can sharpen free hand, so I'm not totally incompetent. However, I can't seem to sharpen a convex edge for the life of me. It doesn't seem like it can be any easier. So, this is my question....

Roughly, how long does it take to get an edge as sharp as, let's say, hair shaving sharp? Maybe I'm expecting too much, too soon and not staying with it long enough. :confused: I can't even get my Fallknivens, which come with a convex edge, hair shaving sharp. They slice paper, but that's as good as it gets.

Looking forward to some insight, while I get back to my sandpaper and mouse pad.
 
JohnnyO said:
I've seen all the demos. Read all the instructions. I can sharpen free hand, so I'm not totally incompetent. However, I can't seem to sharpen a convex edge for the life of me. It doesn't seem like it can be any easier. So, this is my question....

Roughly, how long does it take to get an edge as sharp as, let's say, hair shaving sharp? Maybe I'm expecting too much, too soon and not staying with it long enough. :confused: I can't even get my Fallknivens, which come with a convex edge, hair shaving sharp. They slice paper, but that's as good as it gets.

Looking forward to some insight, while I get back to my sandpaper and mouse pad.
Click to expand...



:confused: Sandpaper and mouse pad ? :confused:




Bark River black compound on a leather strop is the easy answer. :thumbup:




Big Mike
 
It shouldn't take long.

It could be you're either using too high of a grit or too low. If you're using like 1k grit or higher, drop down to at least 500 and work up a burr on each side, then go back to the higher grit. If you're using under 1k, get stropping compound or higher grit sandpaper like Big Mike and sweet_hitch-hiker suggested to use.

If it's not that, without intending offense, it could be you're not hitting the edge and instead of sharpening, you're thinning the knife near the edge, in which case you need to lift the knife up to a higher angle. If you're forming a burr, this is not the case, but if you aren't, it could be the problem.
 
I've tried taking knives from a 400 grit up through 2000. Then, on some knives that already had a decent edge, like my fallknivens, I would work only with the higher grits. I thought 2000 grit would give me a pretty good edge, but slicing paper is as good as I ever got.

I'm definitely hitting the edge. I've been sharpening for a long time and do a good job free hand, which is suppose to be difficult to learn. I find it funny that, convex sharpening seems to be the easiest way to sharpen, yet, I learned free hand faster.

I've seen many people post their convexed edge knives, with a highly polished edge done only with sandpaper. I never got that kind of result. Never tried stroping, with a compound. Maybe that's the answer.
 
I use a Edgepro on all my knives with a convex grind and they are shaving sharp.

However if you are intent on keeping the convex grind right down to the edge then use the mouse pad and sandpaper by all means. If this is what your using and you are really good at freehand but getting a bad edge, then you are probably pressing to hard on the sandpaper with the blade. Use only the wieght of the blade as you make your strokes. If you press to hard you will round the edge as you go.


Bill
 
Even at 220 grit you can have shaving sharpness, not the greatest but it will shave a few hairs. As you progress through the grits the quality of the way the edge cut the hair should continue to increase along with the feel of sharpness. Once you reach 2k the edge should at least feel hair popping sharp with minimal amounts of burring.

Depending on how fresh each piece of paper is will also be a factor in how sharp the edge is after every grit. The more used the finer the finish becomes but at the same time the paper looses a lot of its effectiveness and can make for more struggles.

Pressure is also another huge part of convex sharpening, too little and you create a shallow convex that becomes easily damaged. To much pressure and you can end up with a blunt non shaving edge though one that will still cut and slice paper. Pressure and angle also give you the shape you desire of the edge, this is where things get tough because you must understand what's best for the blade and steel. Through use and repeated sharpening you will start to get a feel for what is best for that blade and eventually find the optimal shape.

Remember that angle control is still important, you can't get sloppy just because its "more forgiving".
 
Hey Johnny,
With the exception of my mini-Canadians, I cannot get my other Bark River knives hair "popping" sharp. That is NOT to say they are not sharp!, they are, rather, it is just to say I cannot get them to pop hairs about 1/8" above the skin. Both mini-Canadians will do it after 2K and stropping with green and then white compound, when I'm doing my part.

I use the strops below. They are approx 3" x 11" x 3/4" pieces of wood, with 8oz leather glued on both sides. Then sandpaper of grits between 320 and 2k is taped on both sides. Most of the sharpening for me is done on the 1500 and 2000 grits.

I hold the strop in my left hand, palm up. Then, as I "strop" with the knife in my right hand, I can adjust the angle of the "strops" ever so slightly while sharpening. As others said, you might either be sharpening at too steep, or too shallow, an angle. Each convex blade takes its own angle, and I've found it can take a while to get used to each different knife. I own about 13 or 14 convex Bark Rivers, and I attest to you each one has its own learning curve...its own angle that it wants. You have to find yours, then it'll come to you.

As far as time goes, it depends on how far you let the edge go before sharpening. Most of the time, 5 minutes of paper and compound will bring my edges where I want them. But if it's been a long time since I sharpened a certain knife, even if it's not "dull" to start with, it can take me 30 minutes or more, because I'm "re-learning" that particular knife. Does that make sense? I may not be explaining it properly.

Here's my "kit":

Side one---
convex-01.jpg


Side two---
convex-02.jpg
 
Hitthespot said:
I use a Edgepro on all my knives with a convex grind and they are shaving sharp.

However if you are intent on keeping the convex grind right down to the edge then use the mouse pad and sandpaper by all means. If this is what your using and you are really good at freehand but getting a bad edge, then you are probably pressing to hard on the sandpaper with the blade. Use only the wieght of the blade as you make your strokes. If you press to hard you will round the edge as you go.
Bill
Click to expand...

If you are using an older style foam backed mousepad it is very easy to put too much pressure on the knife. It takes very little pressure. Some people prefer to use a peice of leather under the sandpaper instead of a mouspad. Personally I have never tried it.

I only go to 1200 grit, then strop with black, then green compound and can get all my knives shaving sharp.

Stropping with only the black compound is enough to get shaving sharp, so one strop is all you really need, I just like to take it up the extra notch.

Kevin
 
Sounds like pressure might be the problem. I am using an old "softer" mouse pad. I try to put just enough pressure to see the pad indent a little. However, it's starting to sound like that may be too much. I'll try sharpening with only the pressure caused by the weight of the blade.

Last night I ordered a Bark River strop and compound. I'm not about to give up. The convex edges I have on my Bark River knives are great. They cut great and are nice and strong.

Thanks for everyone's help!
 
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