Blade Geometry: The variability in scandi, sabre, and flat grinds

It's not as simple as they make it out to be.

Although the differences between the scandi, sabre, and flat grinds are clear, each knife design within these categories can be wildly different and even behave more like a knife within a different category.

In general, common belief is that the scandi grind is superior in battoning wood and in wood carving tasks. The flat grind is superior is slicing and fine cutting, while the sabre sits right in the middle as a good combination of the two— both strong and slicey, but no champion of either task alone. 

However, some think the sabre beats the scandi with battoning. Some think the scandi performs in slicing better than the flat. Some think the edge of a flat ground knife is too thin whereas others believe the this edge of a scandi is too delicate. There is too much misinformation out there to make a clear choice on which to use for a particular purpose. 

To shed some light on this confusion. We are going to look deeper into cutting edge geometry to identify the reason why there is no one best grind, and furthermore, that the blade geometry of the individual knife --regardless of grind category-- is what's most important.

We can say that there are five major factors in the blade geometry of a knife as it pertains to cutting:

  • Blade steel and heat treat.
  • The thickness of the blade steel.
  • The overall contour of the cutting edge (Wharncliffe, drop point, tanto, etc.)
  • The style of grind (sabre, scandi, flat, etc.)
  • The angle of those grinds relative to the width and thickness of the blade.

The last bullet point is what we're focusing on. What it comes down to in terms of cutting is the angle of the cutting edge. Change the angles and you effectively make one style of knife perform more like another style.

Check out this graphic that illustrates the point: 

Blade geometry. Scandi, flat, and sabre grinds. Knife grind comparison. Cutting edge shaprness. Sabre vs scandi vs flat grind.

In figure one all of the cutting edges (in red) are at the same 30 degree total angle. On the scandi, the "shoulder" or transition from cutting edge to flat (indicated by the arrow) is more extreme than the other two. With the sabre and flat blades in figure one, the cutting edge doesn't transition to a flat, but rather the primary bevel which makes the initial shoulder a softer transition.

In this comparison, all three would have a similar initial cut due to all being 30° (not taking into account things like overall blade weight, etc.), but then the sabre and flat grinds would slice more keenly due to their relatively thinner blades above the cutting edge. The scandi would perhaps split wood a little better once the shoulder was in the wood, but it's width at the shoulder compared to the others would limit its ability to slice well beyond the initial shallow cut.

In figure two I've changed some of the angles. The shoulder of the scandi was moved up to achieve a keener 26 degree cutting edge. The flat grind was thinned out a bit more to also to match the cutting edge angle of the scandi. The sabre's second bevel shoulder (red arrow) has been lowered to match the scandi. This could be called a "low sabre grind" compared to the "high sabre grind" of figure one.

 This is all to show that basic comparisons that people make regarding these three grinds may generally be true, but the variability in actual cutting edge geometry can disprove those assumptions. Here is another illustration to make the point:


Blade geometry. Scandi, flat, and sabre grinds. Knife grind comparison. Cutting edge sharpness. Sabre vs scandi vs flat grind.

In figure 3, we see that *if* the blade grind correlates to the sharpened cutting edge angle, you will achieve some overlap in cutting performance. A flat grind out of 1/4" steel will be similar to a high scandi on 3/32" steel. A low sabre out of 1/8" steel will be similar to a medium scandi out of 3/32", and the comparisons go on.

It's more complicated than what has been put forth here, but this part of the equation is underrepresented. Hopefully this clears up some confusion around the similarity and differences in cutting performance on these blade grinds.

As so many have said, in the end it's about preference and end user capability. Redroot primarily makes sabre ground outdoor knives and flat or rounded high-sabre kitchen knives because that is our Western tradition and because that's what the the Redroot team have grown up using effectively in the camp and kitchen.

Read about our kitchen knife design principles  and our outdoor knife design principles to help clarify our particular choices.

If you are interested in working with us on a custom project, please check out the Made-To-Order page.



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