Proper sharpening angle?

LittleBill

LittleBill

Joined
Jan 25, 2010
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So does the proper sharpening angle differ for different blades/intended uses?

Is the right angle for a knife used for chopping/utility work different from that for a fighting knife used for thrusting and slicing?

and yes: kudos to Ankerson for sharing his sharpening mistake with us: we all learn together from each other, we all get smarter...
 
It can yes. :)

This is my opinion, I am sure others will have different ones. :)

Choppers, around 40 degrees (20 degrees per side)

Fighting knives and folders can be 30 degrees (15 degrees per side)

Kitchen knives can go as low as 20 degrees (10 degrees per side) and if it's really sharp the blade will fall through what you are cutting with just the weight of the knife. :D
 
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Ankerson said:
It can yes. :)

This is my opinion, I am sure others will have different ones. :)

Choppers, around 40 degrees (20 degrees per side)

Fighting knives and folders can be 30 degrees (15 degrees per side)

Kitchen knives can go as low as 20 degrees (10 degrees per side) and if it's really sharp the blade will fall through what you are cutting with just the weight of the knife. :D
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Basically, what he said. Slicers need a sharper blade than choppers. Hence the fact that razor blades have 20 degrees, sometimes even 15 degrees, and choppers can go up to 40.
 
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20 degrees per side on a chopper? Someone forgot to tell me that when I reprofiled my Dogfather :D
 
Ankerson said:
It can yes. :)

This is my opinion, I am sure others will have different ones. :)

Choppers, around 40 degrees (20 degrees per side)

Fighting knives and folders can be 30 degrees (15 degrees per side)

Kitchen knives can go as low as 20 degrees (10 degrees per side) and if it's really sharp the blade will fall through what you are cutting with just the weight of the knife. :D
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Well stated. I'd like to know more about your mirror bevels. They're amazing. Are there any shortcomings to having that mirror edge? What tools do you use?
 
Iboschi said:
Well stated. I'd like to know more about your mirror bevels. They're amazing. Are there any shortcomings to having that mirror edge? What tools do you use?
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There really aren't any short commings of a mirror edge as long as it's the proper angle. :)

I use the Edge Pro Apex to sharpen with. :)
 
I would not go under 22 per side for a chopper, and up to 25 per side would be good. A thicker edge will be much toucher, and stay sharper Longer.

For a general purpose, or hunting knife 20 per side works great.

I also keep my folder's at 20 unless a slipjoint. I keep them at 15 per side.

Kitchen knife, 10 to 15 per side is good.



Most factory Folders(such as CRK) set there factory edge at 17/18 per side, and there fixed blades at 20 per side. I like that on there folders because I can set a back bevel when I sharpen it at 20.

Handmade fixed blades will vary, depending on the maker. Most I have came set at 20 per side. But some vary...for example, the Nick Allens(NWA) I got in this week both are at 22 per side, and the Dozier I got in is at 15.
As far as I know Dozier sets his edge thinner than any I know, and they slice great, but won't hold up to abuse like a thicker edge will.

A good edge between med and fine will be the best for slicing/cutting. Just a bit of tootheness will cut through certain media, such as meat for example, better than a highly polished edge.
 
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My Dogfather has a convex edge that is about 15 degrees per side at the edge and 10 degrees per side behind the edge. I've chopped apart seasoned foot thick logs and batoned stuff as big as the blade can take without edge damage. I find that thinner edges on choppers are essential to getting a good bite, but there is a point where you can go too thin. My knife has outperformed Killa Zillas and Fat Battle Mistresses with the stock edges. I'd love to see what a FFBM is like with a 12 degree per side edge though :)

mwayxw.jpg
 
I eyeball it, then test it out to see what works best.

There are a lot of things to consider choosing that angle, including how you apply it. The final angle may change for a certain knife once you get into a routine of use, but Ankerson gives a good starting point to tweak from.
 
Cliff Stamp was of the opinion that people failed to get maximum performance from their knives because they set the edges too thick. Especially in the case of modern super steels. He would run at pretty acute angles, even under 10 per side, until he saw damage, then back off the angle slightly, or add a microbevel to strengthen the edge.
 
I think it's important to differentiate between a thin edge and thin back bevel. I agree that 20 degrees per side is appropriate for a chopper, but that doesn't mean the blade has to be horribly thick at the edge. A thinned out blade with a steep micro bevel is a good compromise IMO.
 
Agreed, Josh J. and Guy. In fact I still have a video of my chopping with Guy's Ruck or AK, forgot which....but it was stripped and the edge reprofiled. Best chopper I've ever used. I'll post the video if you guys would like.

Cliff Stamp was pretty smart about how he optimized his knife edges. That's probably the most important point he raised regarding knives. With choppers it's the most essential to maximize edge performance, since the work done with them can be so fatiguing even to well conditioned men.

For example with folders a lot of people talk about 20 degree or 15 degree edges, which is better. I've taken some down to 5 degrees per side, then microbeveled at 10 degrees per side, and the only thing that happened to the knife was it cut better than anything else I owned. It's surprising how thin you can take some steels. Talking about this makes me want to go to work on my Swamp Warden...
 
The edge thinness and the use of the knife go hand in hand ... fillet knives and chopping knives being classic examples .... the "super steel" arguement also depends on the Rc hardness of the blade ... a higher Rc lends itself better to thinning the edge but if it fails it may well chip out and mean a lot of re-profiling work ... not easy on a high Rc "hard" steel ....

I have on a personal level seen no radical difference going below 15 degrees save that it risks damage more easily .... 15 degrees will give you awesome slicing on kitchen and slip joint knives ... never seen the need for less than that .... even on filleting knives ...

20 degrees and a 15 degree back bevel per side is a great "combo" for me .... all my multi duty knives work well on this .... and field sharpening with a Sharpmaker is also a bonus on saved time and good performance retention....

Convexing is something I try to keep to the 20/15 per side profile for the edge but I take the thickness from the shoulder to the spine to more of an appleseed shape than a pear drop shape for the fully convex profile ...the sharper curve helps with biting deep on chopping ...

The thinner the edges the more they need to be "tweaked" by stropping in my experience and can "roll" a lot more quicker .... at the end of the day "sharp is sharp" and if it is plenty sharp at 20/15 per side my advice is stick to it as it will last a lot longer ....:thumbup:
 
PeterPHWS said:
I have on a personal level seen no radical difference going below 15 degrees save that it risks damage more easily .... 15 degrees will give you awesome slicing on kitchen and slip joint knives ... never seen the need for less than that .... even on filleting knives ...
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What knives did you take thinner and arrive at this conclusion with? If possible do you remember their steels and grinds?

20/15 per side my advice is stick to it as it will last a lot longer ....:thumbup:
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Hmm, I've had the opposite experience. My knives with thicker edges seem to dull quicker than the ones with thinner edges. Also, when both knives have gotten dull, the thinner one works a lot better than the thicker one. I did a few pass-arounds and give-aways of thinned out knives and some users here reported similar findings.
 
The kitchen knives I have tried this on are a cross section of steels but all flat ground .... it was as true for my cheap stainless peeling/salad knives ... probably 420J... as it was for my best Chef's knife ... an R2 Hiro Itou Sanktou....

Img741.jpg


Using it on a chopping board the 15 degree edge was a great balance of extreme cutting and edge retention.....15 degrees each side is not "thick" ..... it is "thin" and as thin as Spyderco recommend going on all of their knives which use a number of top steels ....

My fillet knife is a Normark and uses a Scandanavian Stainless ... this I have taken down to 10 degrees on a Lansky and it dulled quicker than at 15 degrees on preparing fish and cutting strips for smoking Venison .... I should say with the Normark knife it was also a case of "rolling" the edge as well ... scalpels are sharpened at just slightly less than 10 degrees per side (17 inclusive) and if you ever use them for tasks like removing glued on rifle butt pads to enable an adjustible one to be fitted .... (this type of rubber really needs a scalpel to cut it as it is very dense) .... you see how edges this thin can easily roll .....but on this sort of material there is a difference easily seen between a knife and a scalpel edge ....the resistance to the cut is the main one ....but these type of materials which show the difference are not many ....
 
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The type of blade steel and heat treatment also comes into play as well, for instance, you can have lets say two of the same blade but one is 1095 and the other D2, you would be able to shape the edge thinner on the D2 than the 1095. So if you were using both types of blades for the same work say cutting cardboard you could have a thinner edge on the D2 blade because edge retention would be better so you wouldn't have to sacrifice cutting ability for edge retention as much as you would with 1095.

If I'm wrong please correct me. Pretty much what Peter said, so I don't think I helped much....

Thanks,
Floyd
 
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