Are bad slicers *really* bad slicers?

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Sharperthansticks

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Are bad slicers really bad slicers? Why not just use a more aggressive sharpening angle? The Kizer Degnan Guru isn't a great slicer out of the box, but with a 15 degree angle (per side) on it, it slices well. Why all the fuss about which knife slices well and which doesn't, if you can just change the grind angle?
 
The angle on the secondary bevel is definitely one factor, which as you say, we can change, thankfully.

But the primary grind matter too. A lot.

Put a 15 degree edge on a Delica and a 15 degree edge on an XM18 Spanto and I'm pretty sure I know which one will slice better.
 
halden.doerge said:
The angle on the secondary bevel is definitely one factor, which as you say, we can change, thankfully.

But the primary grind matter too. A lot.

Put a 15 degree edge on a Delica and a 15 degree edge on an XM18 Spanto and I'm pretty sure I know which one will slice better.
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Agreed. I've knocked down the angle on plenty of knives. It will only help so much.
 
Whatever the angle of a primary edge, a hollow grind will bind up slicing tall objects in a way which a similar FFG will not from my experience. I find this even with a shallow hollow grind like on my Case Sodbuster. I've noticed this specifically with fruit, vegetables and cardboard.
 
Like others have said, you can get the secondary bevel as sharp as you want, but if the primary bevel is too thick and/ or too short (like a flat saber grind) it makes it more difficult for material to flow over the surfaces of a knife.

Thin, full flat grinds tend to slice really well because the surfaces of the knife don't fight/ hang up in the material as the edge cuts.
 
halden.doerge said:
The angle on the secondary bevel is definitely one factor, which as you say, we can change, thankfully.

But the primary grind matter too. A lot.

Put a 15 degree edge on a Delica and a 15 degree edge on an XM18 Spanto and I'm pretty sure I know which one will slice better.
Click to expand...
Taking what you said but adding. Take a delica with 25 dps edge and a xm 18 with a 15 dps egde, my moneys on the delica to still slice better. Way better.
 
The edge angle is important, but the width of the edge shoulders is even more important. Typically, production knives come 0.025 inches behind the edge or thicker -- often much thicker. When edge shoulders narrow below 0.015 inches they become good slicers.

Look at Ankerson's old tests. The best slicers were less than 0.01 inches behind the edge.
 
When I think of slicing, my mind typically jumps to cutting activities where the entirety of the blade passes through the cutting media, as with vegetables, cardboard, and similar things. For that, I honestly think a relatively minor adjustment to the edge angle is significantly less important than the factors listed above, namely, grind height and type, stock thickness, angle of primary grind, thickness of the edge at the shoulders and even the height of the blade.
 
Take any "bad slicer" and use it to cut long strips out of double walled cardboard. Then use a Delica or something similar. You'll get the idea.

Fixing the edge geometry will help a knife cut, but as Insipid Moniker Insipid Moniker pointed out, when the full width of the blade has to pass through the cutting media a thick blade will have wedging issues. Regardless of the edge geometry. I generally try to avoid folders with a thickness over 1/8" for that reason. Sometimes you can get by with thicker blades and still slice well, Spyderco is good at it, but generally thin is king.
 
As many others have said... try cutting cardboard with a Medford at 15 DPS and an Opinel at 15 DPS.
 
One other point to add. You can make a bad slicer (i.e. one with a thicker primary grind) into a better slicer by putting a more acute edge on it for sure. One thing to remember when you do this though is that at this point the steel type and heat treat become much more important factors in terms of slicing ability. A thicker ground knife is going to rely on the steel in that acute edge bevel remaining sharp much more significantly than a thinly ground knife will need to, in which the geometry is helping its performance rather than hindering it.

Some knives with thicker grinds can indeed be made to slice better than they otherwise would with an acute secondary bevel. But then you are relying much more heavily on the steel for strength and longevity of sharpness. Whereas a Delica will just keep on slicing well long after the secondary bevel is dulled, simply based on its geometry.
 
T.L.E. Sharp said:
Take any "bad slicer" and use it to cut long strips out of double walled cardboard. Then use a Delica or something similar. You'll get the idea.

Fixing the edge geometry will help a knife cut, but as Insipid Moniker Insipid Moniker pointed out, when the full width of the blade has to pass through the cutting media a thick blade will have wedging issues. Regardless of the edge geometry. I generally try to avoid folders with a thickness over 1/8" for that reason. Sometimes you can get by with thicker blades and still slice well, Spyderco is good at it, but generally thin is king.
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Yup. The Chapparal is about the best slicer of the modern folders I own.
 
I like thin stock. Knives are made to pass through matter and the less wedging the better. I adhere to the theory that a knife should be no thicker than it needs to be for the given tasks it may be called upon to preform. For most knives that is not very thick.

As has already been said, it is combination of edge bevel angle, behind the edge thickness, primary grind angle and blade stock thickness. A pronounced distal taper from plunge line to tip like Spyderco uses on their full flat grinds can also give you a blade that is progressively slicier as you progress towards the tip. For example the Para2 uses 3.7mm stock but the last inch of the blade near the tip is quite thin and slicey.

My appreciation for knives that slice is why I am a Spyderco junkie. Many modern folders are thicker than I like. I am Spyderco spoiled. They are not the only company who makes nice slicey knives but they do it well.
 
Can’t add anything else that’s already been said.
I have a XM18 spa to that I sent to Big Chris to have it reground to a slicer. At the time, I also had a xm18 slicer from the factory. When I got it back, the whole blade was thinned out making it a difference of night and day compared to the factory slicer.
So yes, a slicer on some knives are really bad slicers.
BTW, I’ve read here that several people have sent their knives to reprofilers to have a better slicer.
 
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