A Question About "Behind the Edge" and a Question About Scandi Grinds

[rummels]

I apologize if the answer to my questions are already on the forum.

Regarding "behind the edge", I have searched and have found many, many references to the term "behind the edge", but no clear definition of what it means. Specifically, I am asking about this terminology as used by Ankerson, when he describes the Geometry Measurement of a knife he has tested as being ".012" behind the edge".

My assumption is that it means that the thickness of the knife blade is 0.12" where the primary and secondary bevels meet.

My second question is regarding scandi grinds. There seems to be some disagreement (or confusion) about what this grind is. Some of the definitions I have found describe the scandi grind as being similar to a flat grind blade except that the bevel starts at about the middle of the blade, and not the spine. But others say the scandi blade has a flat bevel that starts at the spine of the knife. And others say it has a secondary bevel, while some say it doesn't have a secondary bevel.

Any help would be greatly appreciated.
Thanks
Rummels

 

[Rich S]

Can't answer your first question. There are several view points on what exactly constitutes a "Scandi grind" (I collect Finnish puukko and other Scandi made fixed blades). Most Scandi's have the bevel from the about the mid line of the blade (exactly how high or low depends on the maker). Some folks say it is a flat grind from the mid line to the edge. Others say that most Scandis in fact have a slight secondary bevel at the very, very edge. I made and sharpened them both ways. For ultra fine work that requires a super sharp edge, I use a total flat to the edge honing. BUT, that is not practical for routine daily use; so I've honed most of mine to the edge then do a stroke or two drawing away from the edge on a 1500 grit emory or strop. That gives a very slight secondary bevel at the edge which holds up to routine use better. Just my way, I'm sure others will join in with different view points.
Rich

 

[HeavyHanded]

I also cannot answer the first question, but am looking forward to other responses.

As Rich says, how far up the grind goes will vary by maker - I have never seen one that went all the way to the spine. Most will come from the factory with a slight secondary bevel along the edge - whether this is intentional in every case is not clear to me. Again, per Rich's response having a single cutting bevel makes for better performance for specific wood working. Making the edge slightly convex or adding a secondary bevel will toughen it up quite a bit for general use.

In practice when sharpening them freehand it is time consuming to make them 100% flat, a natural slight convex of a degree or so from shoulder to edge is my norm and I leave it at that, stropped on paper over a stone or Washboard block.

 

[awestib]

At least from a knife maker perspective "thickness behind the edge" means really thickness of the future cutting edge before final sharpening I think - so yes, where the final bevel meets the previous bevel.

 

[Obsessed with Edges]

In my own mind, I equate a Scandi grind with a single, WIDE & FLAT bevel (on both sides of blade) starting somewhere below mid-blade and extending all the way to the true cutting edge. I've also seen & read of others including a very small microbevel, though I'm also not sure whether it's intentional from the maker or just incidental (or incompletely apexed). The one example I have is a Helle Scandi ('Dokka') folder, and it's bevels comprise the lower ~0.25" of the blade's full width (1" near the heel/ricasso). Mine came with an odd microbevel that wasn't very sharp at all (wouldn't cut paper reliably); I'm not even sure it was intentional. I fully re-ground the bevels to a full & crisp apex, and it's a laser now @ 9-11° per side.

In tandem with the wide bevels, I'm also inclined to believe the much narrower edge geometry, at/below 20-25° inclusive, is characteristic of the Scandi grind, as compared to other blades with similarly wide bevels but more 'normal' edge geometry typical of general-use knives, at ~25° inclusive or higher.

Here's a description of a Scandi grind from a vendor site (Ragweed Forge), whom I think has reputable knowledge of these blades:

"The Scandinavian Grind

The Scandinavian Grind is a wide flat bevel that runs to the edge of the blade There is little or no secondary bevel. The primary angle is engineered to match the quality of the steel and intended use. The result is a very keen edge that provides excellent control of the cut. The downside is that a full Scandinavian edge is fragile. It can be strengthened by a bit of secondary, which may be as little an aggressive stropping.

The advantage is that it can be resharpened until the blade is worn away, without changing the angle of the edge. No jigs or other gadgets are required. All that is required is to lay the bevel flat to the stone, and work the entire surface of the bevel. It forms it's own guide. This requires some patience, but minimal skill. This is the ideal form in a culture where everyone is expected to use and maintain a knife regularly. It's also ideal if you expect to sharpen your knife in the field, and don't want to carry a tool kit around. There is another advantage to the Scaninavian grind. In earlier days knives were often used for carving wood. Many household items were made by the user. The Scandinavian Grind gives excellent control in woodcarving. If you carve wood, you will probably find that the flat bevels give you better control of the cut."

David

 

[REK Knives]

Rummels, this thread may help a little bit. But you are correct in that when most refer (and when Jim Ankerson refers) to the thickness behind the edge we are referring to the thickness at the transition between the primary and secondary grind. Now the point has been brought up by Chiral.Grolim that there needs to be a specific point of depth from the apex that needs to be defined since when you begin speaking about full convex blades and such you don't really have any specific point to measure like on a v grind. But for conventional v grinds, this is what we mean.

Now in regards to scandi grinds, yes, you will get varying definitions from all over the net, but I think the general consensus is that a true scandi grind is one in which all you have is a primary grind, there is no secondary. It is essentially a zero grind from, as David pointed out above, below the center line of the blade... at least that's how I tend to think of it. Scandi when about 1/4" of the blade width is used, and the rest I refer to zero grinds lol, although there is some cross over I am sure.

Edit for example purposes:

So there are psuedo scandi grinds, which have much lower cutting ability than a normal scandi, such as the Habilis Bush tool. At least all the ones I have seen have a secondary bevel, like this:

Whereas a true scandi should not have a secondary:

Although now that you bring it up, it is interesting... I wonder if a zero ground emerson would be referred to as a scandi ground knife? lol

 

[rummels]

Thanks to everyone for your replies. The info provided has been very helpful.

 

[other memory]

I apologize if the answer to my questions are already on the forum.

Regarding "behind the edge", I have searched and have found many, many references to the term "behind the edge", but no clear definition of what it means.

My comment assumes a bevel and flat grind that goes directly to the spine (rather than say a saber grind, which has a secondary bevel leading to the flat). That's a measurement taken where the bevel meets the primary grind. Or, possibly a measurement taken somewhere between the apex and where the bevel meets the primary grind. If that measurement is taken somewhere in-between the apex and where the bevel meets the primary grind, a reader interpreting that info would need to know what point on the triangle the measurement was taken. I see a lot of makers throw that term around without communicating how far up the bevel they took the measurement and what angle they ground the bevel. If you want to know a knife's geometry, ask for specific point measurements and angles.

 

[samuraistuart]

There are usually THREE different ways a person could be referring to edge width. The edge width before the secondary is applied. The edge width at the shoulder of the secondary/primary. And a measurement taken at a specific point from the apex.....say.....0.125" above the apex.