For the physics guys – what are the structural benefits of a saber grind?

nydude

nydude

Joined
Jun 10, 2009
Messages
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Hey guys!

I took my satin INFI Scrapper 5SE on a great snowboarding / outdoor grilling weekend recently. It’s now my “go to” user for pretty much everything, because of how light and comfortable it is. I did tons of food prep and realized that slicing is a bit tougher with the saber grind.

I’m assuming there is some sort of lateral strength benefit or something? Does anybody know how a saber grind affects performance? Does anyone have a preference?
 
I'm not a physics guy but I will throw out my ideas about it. A saber grind is probably stronger than a full flat grind on the same blade at the same thickness. The edge and blade profiles, however, are the same that they would be on a much thicker blade, if that makes sense. For example, I have a .17" thick Meaner that has a full flat grind. I also have a .14" thick Leaner with a saber grind. The edge and blade profiles of both blades are the same, up to the saber line, then they change. The benefit of a saber grind, to me, is I have the same blade in a lighter, less handle heavy package. The tip and cutting area retain the thickness they need to have more strength but you have less metal in the handle thus lightening the load, so to speak. So it makes sense that you might have a harder time slicing with your S5SE because the blade profile is about the same as a knife that is .22" thick with a flat grind.

Just my two cents, hope it helps.

Solstice said:
They look Freaking Bad Ass!:cool:


:D:p



.
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Oh, and this too.:thumbup::thumbup::cool:
 
I've never done a side-by-side, but I always thought it was the exact opposite. It sliced easier b/c the angle goes to zero after a certain point.

Or maybe I'm thinking stick-ability when chopping wood.

Basically, I'm just padding my postcount at this point. Sorta like Solstice just did, only looking like I'm trying. LOL
 
Saber grind vs full flat grind - you have steeper side angles and therefore more friction.
the flip side of this is that a heavier, steeper sided blade will often be better at chopping, because the wedging action will tend to pop chips out.
think thin paring knife compared to a wood maul. One makes paper thin slices of tomato, the other converts the entire tomato into a paper thin smear mixed in with the pieces of your table scattered across the floor. :)
 
oeser said:
I'm not a physics guy but I will throw out my ideas about it. A saber grind is probably stronger than a full flat grind on the same blade at the same thickness. The edge and blade profiles, however, are the same that they would be on a much thicker blade, if that makes sense. For example, I have a .17" thick Meaner that has a full flat grind. I also have a .14" thick Leaner with a saber grind. The edge and blade profiles of both blades are the same, up to the saber line, then they change. The benefit of a saber grind, to me, is I have the same blade in a lighter, less handle heavy package. The tip and cutting area retain the thickness they need to have more strength but you have less metal in the handle thus lightening the load, so to speak. So it makes sense that you might have a harder time slicing with your S5SE because the blade profile is about the same as a knife that is .22" thick with a flat grind.

Just my two cents, hope it helps.




Oh, and this too.:thumbup::thumbup::cool:
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Thanks Oeser, but Why would there be less metal in the handle? wouldn't it be thicker?
 
1066vik said:
One makes paper thin slices of tomato, the other converts the entire tomato into a paper thin smear mixed in with the pieces of your table scattered across the floor. :)
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Haha,.. it's not quite that bad..
 
nydude said:
Thanks Oeser, but Why would there be less metal in the handle? wouldn't it be thicker?
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Just picture the .17" meaner I have, as an example. If you ran it through a surface grinder and shaved .015" off of each side, leaving the blade profile alone, you would come out with a .14" saber grind Leaner. Same blade profile, but now it's saber ground and there is only a .14" thick piece of metal in the handle instead of .17" thick. So basically the same knife just lighter because you shaved some metal off to create the saber and thinned it out in the handles. Just imagine how much heavier your S5SE would be if it were .22" thick with a full flat grind. You would have the same angle on the blade profile but a lot more weight in the handle with the thicker material. It's hard to describe without visuals but does that make sense?:)
 
I generally only like saber grinds on thin knives, like Oeser's leaner - it's a way to have the beefy profile of a thicker knife without actually making the knife so bloody thick.

On thick knives, saber grinds are just about my least favorite - the main reason being the abrupt transition between the flat and saber portion of the grind. This harsh angle tends to bind up a bit and create extra friction, especially during batoning and slicing. If you don't believe me, do some batoning with a coated saber ground knife, and look at where the coating wears first - it will be in that transition area, because there's more concentrated force between the material being cut and the blade, and as we all know from intro physics, increased normal force = increased frictional force.

If you want the benefits of a saber grind (ie, putting more weight on the blade without making it thicker, making the blade push wood chips out of the way better due to a thicker profile), you can gain most of them from a convex primary grind, which doesn't have the harsh transition points to bind up while cutting. Or if you don't want to push more weight out into the blade, then a full flat grind is awesome for splitting, since the only place to bind up is the back of the blade.



The one good thing about a saber grind is - it's easy to turn it into a convex grind, just knock the corner off that transition on a belt sander, and you've got you a nice convex, even if it's not a "full" convex, it will perform much the same. Win-win.
 
MustardMan nailed it.

Now what we need is a .15" thick saber ground Anorexic BOSS Street and we would have a winner.
 
Not really a physics question. More of an engineering, strength of material question. From what I remember from schooling(not much mind you,) the only strength advantage that you would gain from a saber grind over a full height grind, assuming both blanks started with identical properties, would be in the cross sectional area of the saber grind, which would make shear, lateral and bending strength higher. Pretty simple really, thicker steel is harder to bend and break. Saber grind= more cross sectional area than full height grind.

ETA: Looks like a physicist beat me to it and added friction to the mix, now its a physics question.:foot: Physicists always showing up us engineers. Thanks MM.:D
 
So you guys are saying a saber ground blade is overall a stronger blade than a flat ground blade. Does this mean in every way or not.
 
OldPhysics said:
But then, it's a very "good" physics question.:);)

I wonder ... can we introduce a discussion of gravity? Perhaps not ...
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I was just about to tell you physicists to go find a gravity related question and let me have this one...

I think we can introduce physics to the problem though. I can swing choppers incredibly fast. At what speed does the drag from the saber ground blade end up overcoming my incredible strength? Is this faster or slower than the full height ground blade?

Go physics...go.

And to answer your question NATO, assuming both blanks were identical to start and one was saber ground and the other full height, yes, the saber ground blade will be stronger. The difference will be negligible I'm sure, but it has more metal in all directions, so it should have higher strength in all ways.
 
Hmmm… The initial thought process to was a lateral strength question, not because there may or may not be more actual metal on a saber, but because in nature different shapes tend too exhibit different properties when pressure is applied, even if the materials are identical….
 
oeser said:
MustardMan nailed it.

Now what we need is a .15" thick saber ground Anorexic BOSS Street and we would have a winner.
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+1 The snake/satin AD's were .15 with a sabre grind. IMO is a great blend of the best. Bring on a A-BOSS ST with sabre grind ! :thumbup:
 
Dennis in MA said:
I've never done a side-by-side, but I always thought it was the exact opposite. It sliced easier b/c the angle goes to zero after a certain point.

Or maybe I'm thinking stick-ability when chopping wood.

Basically, I'm just padding my postcount at this point. Sorta like Solstice just did, only looking like I'm trying. LOL
Click to expand...

Who me???


:D
 
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