Can a knife be Too convex?

W

Washburnedout

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Mar 23, 2014
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With the knife I am currently making, I didn't cut the primary bevel very deep and now after heat treating I have to put an edge on the blade. I was wondering if you can have too convex of a blade, so I know whether to anneal the steel and re bevel or just try putting a usable edge on the knife I already have.
 
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The answer is yes, you can have too convex a blade. My first few were definitely too convex to have a useful edge.
 
tryppyr said:
The answer is yes, you can have too convex a blade. My first few were definitely too convex to have a useful edge.
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How did you fix this problem? I think if I started sharpening it it would hold a useful edge but the blade drops in a tapered U shape then it has a small edge on the end.
 
Cut the shoulder down. Forgive me, as I'm probably talking out of my ass....but after sharpening a lot of knives, not near as many as a lot here, but quite a few, I think a convex edge should start from the edge up as opposed to the bevel down. If you get my drift. In other words, if you try to sharpen from the top down it is very easy to get the edge too thick. Or something......Once you get the edge established then you can work on convexing it.
 
You don't have to anneal the blade in order to adjust your bevels. Just re-grind as necessary. Go slowly with a light touch. Keep the blade cool. Dunk after every pass. Then refinish with your normal hand sanding procedure.
 
Let's start with numbers.

How thick was the piece of steel before you started grinding? How wide? And then, how far up the blade did you cut the primary bevel?

With those numbers we can calculate the angles and figure out how far you are from being able to fix the problem.

- Greg
 
i4Marc said:
You don't have to anneal the blade in order to adjust your bevels. Just re-grind as necessary. Go slowly with a light touch. Keep the blade cool. Dunk after every pass. Then refinish with your normal hand sanding procedure.
Click to expand...

I have hand tools sadly... No grinders
 
tryppyr said:
Let's start with numbers.

How thick was the piece of steel before you started grinding? How wide? And then, how far up the blade did you cut the primary bevel?

With those numbers we can calculate the angles and figure out how far you are from being able to fix the problem.

- Greg
Click to expand...

1/8 in thick 1 to 1 and 1/4 in wide and I cut the primary bevel up about 1/2 inch but I didn't cut it deep enough.
 
Sounds to me like you'll be better off annealing it and doing the job properly. And just by the way, I'd push the bevels higher. In fact, almost all the way to the spine would be good.
 
tryppyr said:
Sounds to me like you'll be better off annealing it and doing the job properly. And just by the way, I'd push the bevels higher. In fact, almost all the way to the spine would be good.
Click to expand...

Yeah if only I had a grinder this would be so much easier!
 
I know. But the truth be told, working with files and sandpaper shouldn't slow you down THAT much. Too many people look for short cuts. Do the work right and you'll be proud of what you make. Do it wrong and you'll struggle to hide it. Don't be afraid of the work. It will make you stronger.
 
Dang Greg that was downright profound! Could put that on a t shirt. And you are absolutely right.
 
I am reading and visualizing "convex- too thick" to be describing a splitting maul/wedge instead of a slicing tool.


IMHO, the axe vs. splitting maul analogy is always a good one to help clarify this stuff. An axe is ground thin and sharp to cut across the grain of wood. A splitting maul is not supposed to be sharp... it's supposed to be heavy and blunt, so it will push the wood apart from the end grain.


Which would you rather have in a knife??? ;) :)

Knife making is certainly an exercise in patience. :)
 
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