Highly polished edge = bad for hard work?

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killa_concept

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May 19, 2009
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Well I got my BK-2 awhile ago and after messing with it for awhile, the edge got a bit dull so I decided to sharpen it. I sharpened it the same way i sharpen my pocket knives and kitchen knives - 200, 400, then 1000 grit flat water stones followed by a stropping on a leather belt - it shaved hair with ease, could whittle a single strand of hair, and had a mirror finish. The second I took it out to baton and do a bit of wood work, it seemed to not work very well and lost it's edge fairly quickly. I kept the same factory angle (20 degrees on both sides I believe)

I've never really had a knife kept around for hacking through wood, so here's my question: is a highly polished edge more suited for kitchen work (meat/vegies), and not meant for harder tasks like batoning through/carving up wood? Would it perform better if I just sharpened it to 200grit then stropped it?
 
1095 is the one steel that I find does not do as well with a high polished edge. I usually stop around 800-1000 grit and lite strop, just enough to knock down the burr. A high polished edge works very well with almost all other steels though no matter the task.
 
If you're working with a lot of fibrous materials, such as paper, cardboard, or vegetation, a "toothier" edge (ie: larger grit finish) is a better option than a finer one. It might not feel as sharp or pop hairs, but it'll chew through these materials better and longer before needing resharpening. Think of a toothy edge like mini serrations.
 
Planterz said:
If you're working with a lot of fibrous materials, such as paper, cardboard, or vegetation, a "toothier" edge (ie: larger grit finish) is a better option than a finer one. It might not feel as sharp or pop hairs, but it'll chew through these materials better and longer before needing resharpening. Think of a toothy edge like mini serrations.
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Hate to burst your bubble but that not really true.
 
i put highly polished edges on my knives and they chop wood very well and still shave after. a lot has to do with the type of steel and how well it was heat treated. killa_concept, maybe you should try a convex edge instead of a v edge.
 
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I was thinking you might be going too acute for the steel, but then 20 degrees per side isn't all that low of an angle.

Is the edge deforming, rolling, or chipping?
 
I would suggest sharpening to 200 and then stropping like you say. Going all the way to 1000 just to baton through wood will ruin that edge lickety split. Using a lubricant like WD-40 on the blade while you baton will help you move through the grain with ease, but it still won't save your edge.

One thing to think about in comparison is an axe edge: Not very sharp, flat grind wedge shape, and large sharpening angle. If an axe edge angle were 20 degrees, the first time you don't hit that wood straight on will likely snap it/dent it/chip it and otherwise destroy it. Now I know using an axe and batoning a knife through wood logs are two separate things, but you are technically using a knife to do an axe/hatchet's job.
That's my 2 cents anyway. Just a suggestion.
 
richard j said:
i put highly polished edges on my knives and they chop wood very well and still shave after. a lot has to do with the type of steel and how well it was heat treated. killa_concept, maybe you should try a convex edge instead of a v edge.
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I don't think i have the skill or materials necessary to manage a convex edge on anything except a camp ax... So you manage to put a 1000 grit finish on your knives, baton through thick wood, and the knife is still capable of shaving?? What sort of steel blades are you talking about, because if I could manage that with my BK-2, it would be awesome

orthogonal1 said:
I was thinking you might be going too acute for the steel, but then 20 degrees per side isn't all that low of an angle.

Is the edge deforming, rolling, or chipping?
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Too small to see but running my thumb over it, it seems to be rolling to one side.... I thought about increasing the angle, but i would think that 20 degrees on each side would be fine for this sort of work
 
Scaevolus said:
I would suggest sharpening to 200 and then stropping like you say. Going all the way to 1000 just to baton through wood will ruin that edge lickety split. Using a lubricant like WD-40 on the blade while you baton will help you move through the grain with ease, but it still won't save your edge.

One thing to think about in comparison is an axe edge: Not very sharp, flat grind wedge shape, and large sharpening angle. If an axe edge angle were 20 degrees, the first time you don't hit that wood straight on will likely snap it/dent it/chip it and otherwise destroy it. Now I know using an axe and batoning a knife through wood logs are two separate things, but you are technically using a knife to do an axe/hatchet's job.
That's my 2 cents anyway. Just a suggestion.
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The way I've always heard it is that the higher the polish, the lower the friction coefficient and the easier it should glide through materials... maybe making the edge slicker is somehow making it harder for the knife to cut through wood?

richard j said:
the knife in this video is one i made from 1075 and i can chop through elm and still shave with the knife http://knifetests.com/kII.html several members have done this or seen me do it with this very knife.
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So is 1095 just too hard a steel to be expecting a shaving edge after wood work? should I just be stopping at 600 grit and then stropping? should I perhaps try increasing the angle?
 
the edges of my knives are around 63-65 rc which is fairly hard. i heat treat only the edges of my knives. i'm not sure how hard your knife is so i cant tell you what to expect.
i know from using my knives that a convex edge works best on them. i should have told you that my knives are a chisel grind with a half convex edge.
 
killa_concept said:
The way I've always heard it is that the higher the polish, the lower the friction coefficient and the easier it should glide through materials... maybe making the edge slicker is somehow making it harder for the knife to cut through wood?
Click to expand...

I've heard the same thing. So logically the knife would slide through wood (and basically any material) easier with a 1000 grit high polish versus a 200 grit. The slicker the bevel the easier it will cut simply from the lack of friction. Another idea is trying the 200 polish the next time you sharpen and leave it at that for batoning. The only thing is you'd be missing out on a 1000 polish for cutting everything else.
 
If there is no honing compound on the strop, you may be leaving a small burr that breaks off when you baton the knife. It is completely reasonable to expect a knife to baton through wood, within limits, and still shave afterwards.

High polish knives handle hard work better, but remember to use a push cutting motion instead of a slicing motion. A high polish knife of adequate hardness will push cut speaker wire (copper and plastic) without damage and still shave, but if you try to slice through it, it will just roll the edge. I batoned a knife of M2 high speed steel at an estimated hardness of 63-65 HRc with a hammer and it still shaved easily. It had been sharpened on a Spyderco Sharpmaker at 20 degrees per side up to the white fine rods, then stropped on honing film from the local woodworkers supply store. The honing film had a grit size of 0.3 microns.

For a reference, Leonard Lee recommends a bevel angle for axes as low as 8 degrees per side, but only for felling clean green wood. Keep in mind, most axes will be made of steel that is far tougher than nearly any knife steel, even if its the same hardness. This helps keep impact damage to a minimum, and axes resist damage from glancing blows surprisingly well, unless dirt or rocks are involved.
 
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