Blade geometry by application, a compilation seeking data contributions

[Pumpiron]

After some informal research here and elsewhere, I've created the following rough draft of representative blade geometry specifications for high-performance knives, and would appreciate your input to adjust and optimize it. With your help, I think a revised iteration could become a spectacular resource for up-and-coming knife makers among other audiences.

Use		steel	hard	Charpy C	spine	edge	edge <	bevel	blade	blade	grind	weight
		class	HRc	ft-lb	thick	thick	dps*2	width	width	length		oz
Razor		AEBL	60	35	0.03	0.005	12	0.04	0.25	1	hollow	3
Paring		AEBL	60	35	0.04	0.007	15	0.08	0.25	3	flat	4
Filet		Elmax	59	35	0.06	0.01	17	0.25	0.3	7	flat	5
Slicer		Elmax	61	25	0.09	0.01	19	0.5	0.6	9	hollow	6
Chef's		AEBL	61	35	0.125	0.012	20	1.5	1.5	8	hollow	10
Skinner		PD1	61	35	0.125	0.015	23	0.8	1	3	hollow	6
Utility		PD1	60	35	0.125	0.018	23	0.65	0.8	5	hollow	7
Tactical		CPM 3V	58	80	0.18	0.025	25	0.6	0.8	6	flat	9
Hunting	min	CPM 154	59	25	0.11	0.015	20	0.6	0.8	4	hollow	6
	max	PD1	62	35	0.15	0.025	30	1	1.2	7	hollow	11
Survival	min	52100	57	30	0.13	0.015	20	0.6	0.8	4.5	hollow	7
	max	CPM 3V	60	70	0.2	0.03	30	1.3	1.5	9	flat	18
Machete	min	5160	52	50	0.09	0.015	25	0.25	1.3	14	flat	11
	max	Z-Tuff	58	115	0.13	0.035	35	0.5	2.3	24	convex	30
Chopper	min	5160	54	50	0.16	0.015	25	1	1.5	10	flat	16
	max	Z-Tuff	60	115	0.375	0.03	35	2.5	3	20	convex	40

I'm primarily seeking input from makers or other highly-informed members about their geometry preferences. It's been mentioned that makers often grind thinner as they gain experience. Please list your own ideal row values, even better as an associated combination for each favorite knife. Values are critical for impact tools, so special attention will be appreciated there. I’d love input such as "Your edge thicknesses look too thin for the intended application. I'd increase [chef's] to … " or especially a few rows in the format of the above table, each describing a favorite knife geometry combination.

To avoid innumerable combinations, my generalized column values are disassociated from rows and treated independently, esp for min/max ranges. Therefore I'm not necessarily assigning a precise charpy-C value to a listed steel or hardness. However your column values for a specific knife can be mutually dependent, all the better. To simplify otherwise exhaustive geometric definition, each entry is intended to be representative, not comprehensively inclusive. Thus a width may be a representative sample in the middle of the blade, and a thickness may be nearer the handle and not reflect distal taper. Obviously there are possible outliers well beyond the intended main-stream ranges, but I don't think we need to address extremes like tuna knives. The subtopics are broad enough for forum-wide debate, so let's please keep discussion high-level, amiable, and on-topic (e.g. let’s avoid degenerating to fighting about favorite steels or chiming in without substantive input).

Thank you very much for your detailed consideration and contributions.

 

[JayGoliath]

Thank you for putting this up.

 

[Stacy E. Apelt - Bladesmith]

I appreciate your efforts and idea, but categorizing steels and blade types and angles and thicknesses into a single chart would be like categorizing women into a single chart of which ones are sexy, which are hard working, which are smart, which make good mothers, etc. There re so many possible combinations and variations that no one could be plugged into a single parameter. Just for example, a high performance Chef's blade could be any of a dozen high performance steels. It will depend on the makers choice, the users choice, and the type of use. Just saying AEBL is the choice is totally insufficient as a guide to a new maker. ( Actually, AEBL would not be my choice for a high performance chef's blade)

Several of the other steels you recommend are not the best for that class.

Note - Anyone looking at the current chart should only use it as a guide, not as knife making fact or recommendation.

 

[NWAlabamaHiker]

I appreciate your efforts and idea, but categorizing steels and blade types and angles and thicknesses into a single chart would be like categorizing women into a single chart of which ones are sexy, which are hard working, which are smart, which make good mothers, etc.

Some of this has already been done! Lol
http://youtu.be/vwbKYcBdVyk

But seriously you're right, I've just started trying my hand at making knives, but I can already tell from just reading and studying about metallurgy in general - that there are almost endless combinations of just steel, heat treat and tempering! That's to say nothing of edge geometry and such.

I do appreciate the fact that @Pumpiron would take the time to study and attempt to put this together. It shows a willingness to learn and we are useless when we stop learning!

 

[JTknives]

Lol my eyes went right to the chef knife as well. AEB-L is a great steel, but so is Elmax, CPM S35-VN, W2, 52100, 1095, white and blue paper steel, and and and.
One thing to remember, its not always about the steel but how it's used. Different steels shine at different tasks better then others but as soon as you say X steel should not be used for X you will have a handful of knifemakers pop up and say thy use it for that all the time and works great.
Steel usage and selection is a very dynamic process depending on a bunch of variables half of which we have control over. The other half is in the customers hands and how thy use it. We do our best to make educated selections taking into account blade shape and use but when it comes down to it there is no perfect steel.

 

[stezann]

A chef knife with a 1.5 inches of blade width with an hollow grind? Everybody will find their optimum, but for shaving you most likely prefer 16-18 degree included, not 12 dps (24 included sharpening angle is for a keen knife, not a razor).
Divergences of opinions aside, working out a nice chart of optimal blade geometries is not a bad idea; the steel will follow, choosing the one that will better fit the intended geometry.

 

[Stacy E. Apelt - Bladesmith]

I also looked at the recommended edge angle. You have dps*2 as the edge< description and have listed a number that is the total (included) angle. That could easily be misconstrued as the angle listed times two. A chopper with a 35dsp*2 edge would have a 70° edge angle. It should be listed either as dps or as the total angle (which is the more correct way). While it is partly knifemaker semantics, it regularly causes confusion to new makers and people from other than USA cultures. Using the complete number is a better choice, as it is an absolute.

I explain it this way, " One of the most important parts of the geometry of a blade is the angle of the edge ...... not half the angle of the edge. In cutting it is this angle that determines the balance between edge stability and edge acuteness. In doing sharpening, you use half the edge angle degrees per side, but that does not change the edge angle .... it is still a whole angle."

I also agree with the others that the grind types will vary a lot. Personally, I have never hollow ground a 1.5" chef's blade. While I love AEBL, it is not my steel of choice for "high performance" chef's blades.