Flat Grind vs. Hollow Grind

K

Ken Cox

Moderator
Joined
Dec 11, 1998
Messages
15,923
In the Endura/Delica update thread, several people expressed a desire for a flat grind.
Why?

I have never seen a true flat grind.
I understand some Nordic knives, puukos, have a true flat grind.
Otherwise, I see a saber grind described as a flat grind, simply because it doesn't have a hollow between the edge and the spine.

And, we don't really have any true hollow grinds, as one would have seen on a straight razor 75 years ago.
My Grandad shaved with a straight razor til the day he died.
In fact, he died while shaving with a straight razor.
Anyway, that puppy had a hollow grind, on one side at least.

Todays hollow grind blades have a hollow behind the edge.
The knife edge actually gets thicker before it runs into the hollow and gets thinner.

So, why would anyone want a flat grind?
With a Nordic knife, one lays the entire flat of the blade on the stone and removes metal from the entire flat.
Yes, very sharp, but one goes through a lot of knives that way.

I think everyone who has asked for a flat grind really means they want a saber grind.
Even then, why?
 
Hollow grinds (both of the sort you identified) choke more easily when cutting through an object larger than the width of the blade.

Edit: I'm with spyken on the terminology here.
 
I thought the pukkos had a saber grind with a zero edge (no hollow between the flat portion of the blade and the edge), and calypso jrs, paramilitaries, militaries have full flat grind with a v-edge? (delicas and enduras are saber grinds)...

or has my understanding of the terminology been all wrong...
 
We want flat grinds ala the Calypso Jr Lightweight. These work better in stiff material like thick cardboard where the shoulders on scandinavian, saber, and hollow ground knifes tend to bind.
 
A flat grind, to me, means one flat surface all the way from the spine to the edge, where it disappears into nothing with no bevel.
Put a bevel on the edge of a flat grind, and one then has a saber grind.
Do I have that wrong?
I have not heard of any modern knife, other than a few puukos and other nordic knives, that do not have a bevel, and therefore, despite their flat grind appearance, they really qualify as a saber grind and not as a flat grind.
Do I understand the advocates of a flat grind for the Endura/Delica to mean the same kind of flat grind to which I refer; one without a bevel?

Now, to save us some time, if the flat grind advocates mean a knife with a mostly flat grind and a final bevel, then what do they mean by a saber grind?
Do they mean a partial flat grind that does not go all the way to the spine, and which has a bevel?
I have seen some Nordic knives with that grind.

I just want to get vocabulary and the mental picture clear in my mind.
 
Saber ground generally refers to a knife with a flat grind that is less than the full width of the blade, full flat grinds go all the way to the spine. Both of these have secondary edge bevels. The cold steel srk is an example od a saber grind.
 
Ken Cox said:
Now, to save us some time, if the flat grind advocates mean a knife with a mostly flat grind and a final bevel, then what do they mean by a saber grind?
Do they mean a partial flat grind that does not go all the way to the spine, and which has a bevel?
I have seen some Nordic knives with that grind.

I just want to get vocabulary and the mental picture clear in my mind.
Click to expand...

FWIW, this is how I understand it. I think Yoda4561 nailed it.

Jeremy
 
Ken Cox said:
A flat grind, to me, means one flat surface all the way from the spine to the edge, where it disappears into nothing with no bevel.
Click to expand...
That is what is frequently referred to as a "zero grind", or a knife with a "zero ground edge", as the edge is the same angle as the primary grind.
A flat grind, specifically a "full flat grind" has a blade whose primary grind is flat from the spine to the edge bevel.
 
saber grind = the current FRN delica (some call it a half-flat grind)
flat grind = the manix (some call it a full-flat grind)

the nordic knives you speak of are also flat grind its just that they have no secondary bevel, only a primary.
 
Ken Cox said:
I have never seen a true flat grind. I think everyone who has asked for a flat grind really means they want a saber grind. Even then, why?
Click to expand...
Years back I would have gone ballistic if someone mentioned a BMW M-Roadster. But, I quit living on planet Paul and accepted the fact that the rest of humanity either does no know or does not care about the differences between a roadster and a convertible.

So, given that you admit you've never seen a knife that meets your private definition of a "true" flat grind, perhaps it's time to leave planet Ken. Rightly or wrongly from the standpoint of pure semantics, the vast majority of us, whether we favor one grind, the other, or neither, use the term full flat grind to refer to one particular grind. We also differentiate between that grind, and what we refer to as either a saber or partial flat grind. Several posts in this thread have already named excellent examples of both these grinds.

As for the why, at least for me the reasons are...

Least weight for a given blade area.

Least binding when cutting thicker materials.

A reasonable compromise between the ruggedness of the saber grind and the delicacy of the hollow.

Aesthetics, I appreciate the clean simple lines a full flat grind give a blade.

Perhaps just a touch of nostalgia as well, as the full flat grind evokes memories of the traditional pocket knife.

And, perhaps for just that reason, I would bet that, all other factors being even, less people would classify a knife with a full flat ground blade as a weapon.
 
The Deacon wrote:

"So, given that you admit you've never seen a knife that meets your private definition of a 'true' flat grind, perhaps it's time to leave planet Ken."

Must I?
I've grown so accustomed to it.
Everything fits.

Seriously, I should have responded earlier and thanked everyone for answering my questions so completely and sincerely.
I now feel as though on the same page.

The light bulb came on with the post regarding the cutting of cardboard.
Yes, I know that the flat grind has a rationale beyond cutting cardboard, but that example provided a good mental picture of the principles involved.

In trying to find where I got my ideas regarding the flat grind, I came accross a discussion of the Scandianavian Grind and realized I had read a description some time in the past which referred to the Scandinavian Grind and the Flat Grind interchangeably.

Anyway, from Ragweed Forge:

-----

The Scandinavian Grind

The Scandinavian Grind is a wide flat bevel that runs to the edge of the blade There is no significant secondary bevel. The angle is engineered to match the quality of the steel and intended use. The result is a very keen edge, which is only slightly less durable than a similar Moran profile.

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. Some patience, but minimal skill is required. This is the ideal form in a culture where one is expected to use and maintain a knife regularly.

-----

Now, would The Deacon please explain the difference between a roadster and a convertible?
 
Straight razors: an interesting subject all in themselves; one side concave and the other convex.
I don't know that anyone strops a straight razor specifically to create a Moran edge, but I don't doubt that it happens regardless of intent.
 
Ken Cox said:
Now, would The Deacon please explain the difference between a roadster and a convertible?
Click to expand...
Sure Ken. The "classic" definition of a roadster is:

An open vehicle with
EITHER two doors, generally without outside door handles OR no doors
AND
EITHER a removable cloth top and removable side windows, often of clear plastic, rather than glass
OR no top and no windows, just a tonneau cover, often with a provision for becoming a poncho, so the car can be driven in foul weather.

A convertible, on the other hand, originally defined a two door open vehicle with rollup windows, outside door handles and a folding top.

Phaetons were four door open vehicles.

In my youth, I owned a couple "real" roadsters, an MG-A and a Morgan +4. My MG-A was a roadster in its purest form, twin fold down half-moon "racing" windscreens with a hand operated wiper on the drivers side to humor the NY DMV, tonneau cover, and doors with no outside handles or provision for windows. Now the term roadster has been commandeered to be a synonym for convertible and some absolute philistines even apply it to phaetons.

Of course I'd guess that having people apply the terms roadster and phaeton to these mechanical contraptions was equally annoying to folks from the "horse and buggy" era, since both these terms, plus many others applied, and misapplied, to types of automobiles, originally defined types of carriages.
 
I had a 1956 Austin Healey 100-4 with no door handles, a removable cloth top, and removable plastic windows.
That made it a roadster.
Thanks.
 
Depending on blade thickness, angle of secondary bevel and size of the wheel on a hollow grind one could generally say that some hollow grinds effectively perform the same as a flat grind. For instance, I have a William Henry Quest that is a hollow-ground, sabre design blade. However, due to the relative flatness of the grind, the thin-ness of the blade stock, and the included angle of 30 degrees - it is even more amazing than the Spyderco Calypso Junior.

You gotta add up all the ingredients to make a whole cake...I mean...figure out what is going to make the most effective matter seperator.
 
Architect said:
Depending on blade thickness, angle of secondary bevel and size of the wheel on a hollow grind one could generally say that some hollow grinds effectively perform the same as a flat grind.
Click to expand...
The differences certainly would be minimized, but, for any given blade, a hollow grind will always create a slightly thinner, and therefor slightly weaker, cross section in the area directly behind the secondary bevel. It might be fairer to say that there are some tasks where a thin blade, of any profile, will do a better job than a thicker one. I imagine a flat ground Delica, with its 2.5mm thick blade, or better yet a flat ground Centofante III at 2mm, would outperform the 3mm Caly Jr. and Stretch for certain tasks. Know for a fact that its easier to quarter onions and potatos with a Caly Jr. or a Stretch than with a Manix, even easier with a FB01 Moran, and easier yet with a K04 Utility.
 
You must log in or register to reply here.
Back
Top