Flat vs. hollow ground blades
Matthew Rapaport
It seems that many of the more popular folding knives have elected to go with
hollow ground blade crossections. I am curious about this. I have a couple
of Spydercos with hollow ground blades, and a few knives (like my Schrade
Cliphanger) that are flat ground. In my experience, the flat ground blade
is more friendly and useful for almost all every-day cutting chores. This
is especially so if you use your folder to cut food from time to time.
The hollow ground blades have thicker spines which break up some foods
while they pass through, while the blades themselves have a tendency to
turn, and not cut straight. I notice that kitchen knives used for food
preparation are exclusively flat ground.
So what explains the popularity of the hollow grind? My flat ground blades
will shave my arm as easily as the hollows. My two favorite sheath knives
are also flat ground with thick spines for strength (for example the Cold
Steel SRK or Trailmaster). In particular, I am really curious about why
Chris Reeve would choose a hollow grind for his Sebenza for which a flat
grind would seem a natural?
--
matthew rapaport Philosopher/Programmer at large KD6KVH
m...@crl.com In God we trust. All others we monitor! qu...@dfw.net
VT
gr...@earthlink.net (bob engnath) wrote:
>m...@crl.com (Matthew Rapaport) wrote:
>>It seems that many of the more popular folding knives have elected to go with
>>hollow ground blade crossections. I am curious about this. I have a couple
>>of Spydercos with hollow ground blades, and a few knives (like my Schrade
>>Cliphanger) that are flat ground. In my experience, the flat ground blade
>>is more friendly and useful for almost all every-day cutting chores. This
>>is especially so if you use your folder to cut food from time to time.
> Hollow grinding is the natural way to do it with automated machinery
>where the billet is run between counter rotating grinding wheels. Most
>mgrs. use automation, hence, they deliver hollow ground blades.
> In the case of the Reeves knives. I would believe that Chris used it
>because finishing by machine is much easier with hollow grinding. Flat
>grinding just about demands hand sanding.
>bob
>gr...@earthlink.net
What Bob said...... :-)
Also there is another given reason that the blade is "easier" to
sharpen since it remains thinner for a greater distance from the
original edge.
The main "problem" I have with hollow ground is that too many knives
actually THICKEN toward the edge -
This is not such a big deal if all one does is shave hairs and score
paper - ie: only use the edge and not have to cut through.
But if you do cut through then that little bit of a hump does make a
difference in a nice clean smooth cut.
However if it is done right the hollow ground should be thinnest
toward the edge -
You can feel this - (your finger tips are highly sensitive) just by
pinching the blade faces and pull toward the edge and you can feel for
any thickening. Or with a little more care pinch lightly at the edge
and carefully push toward the back and feel that way.
BOYE knives are hollow ground "properly" - or at least the ones I
have.
Contrary to what has been said Chicago Cutlery smaller KITCHEN knives
are hollow ground - they are again done "properly" and for years the
two most used kitchen knives were their 5" utility/boner model 62S and
the 3" parer/boner model 102S. The basic blades are thin(ner).
I think Matthew has inadvertantly hit on it - too many knives that we
buy (the non-kitchen type) are made to please the "public" - yes, I am
one. There was a great pursuit for TOUGHER knives that don't "break".
So there was a surge toward THICKER stock at one time 1/8" was
considered pretty thick and more than adequate for an outdoor knife -
but 3/16" became the norm for "quality" knives, then even 1/4" for
"real" men's tough tactical knives.
As Matthew points out we CUT with knives (and mostly DON'T PRY) -
guess what? a nice THICK blade is NOT that condusive to a nice clean
cut - because it now acts more like a cleaver/axe......
I believe none other than our own Mr. AG Russell had something to say
about thickness of knives - in his _advert_ on the AG Russell Deer
Hunter and Bird & Trout models, at the URL:
http://www.agrussell.com/russell/agdh.html
His Deer Hunter 4" drop point model is from only 0.08" stock which is
about 5/64" - just a shade over 1/16"!!
The 3" drop point Bird & Trout model is only 0.06" which is 1/16" or
just under.....
Note the caveat that the Web Site is an advert - and of course you can
choose to believe anything you want........:-)
--
Vincent
v...@pipeline.com
bob engnath
Matthew Rapaport
In article <566j70$n...@venezuela.earthlink.net>,
bob engnath <gr...@earthlink.net> wrote:
>
> Hollow grinding is the natural way to do it with automated machinery
>where the billet is run between counter rotating grinding wheels. Most
>mgrs. use automation, hence, they deliver hollow ground blades.
> In the case of the Reeves knives. I would believe that Chris used it
>because finishing by machine is much easier with hollow grinding. Flat
>grinding just about demands hand sanding.
>bob
>gr...@earthlink.net
>
Interesting. So hollow grind is more common because it is cheaper (i.e.,
less expensive to automate)? That makes sense. Yet I wonder, do other
people find flat grinds more useful in every-day chores as I seem to
do? This issue doesn't seem to be discussed very much.
James & Toni Mattis
bob engnath wrote:
>
> Flat grinding just about demands hand sanding.
It's all in how you look at it.
Flat grinding *allows* hand sanding, and the result looks really nice.
Caveat - you do have to be a little nuts to hand-sand blades.
The wife says I qualify.
James Mattis
"We have met the enemy, and he is us!" - Walt Kelly
Robert Allen
In article <5651cr$l...@crl.crl.com> m...@crl.com (Matthew Rapaport) writes:
+It seems that many of the more popular folding knives have elected to go with
+hollow ground blade crossections. I am curious about this. I have a couple
+of Spydercos with hollow ground blades, and a few knives (like my Schrade
+Cliphanger) that are flat ground. In my experience, the flat ground blade
+is more friendly and useful for almost all every-day cutting chores. This
+is especially so if you use your folder to cut food from time to time.
+The hollow ground blades have thicker spines which break up some foods
+while they pass through, while the blades themselves have a tendency to
+turn, and not cut straight. I notice that kitchen knives used for food
+preparation are exclusively flat ground.
+
+So what explains the popularity of the hollow grind? My flat ground blades
IMHO it's because a hollow grind allows a dagger or saber-grind
style blade to be "razor sharp", even though the effective width
(not thickess) of the blade would normally prevent it. The classic
example is the Gerber Mk I "survival knife". The early ones made
of L6 tool steel were straight daggers. Getting an edge on them
was pretty much impossible. The later 440C models have a wider
blade and a deep hollow grind, and they will shave hair off your
arm out of the box (but not much beyond that if you use them).
+will shave my arm as easily as the hollows. My two favorite sheath knives
+are also flat ground with thick spines for strength (for example the Cold
+Steel SRK or Trailmaster). In particular, I am really curious about why
+Chris Reeve would choose a hollow grind for his Sebenza for which a flat
+grind would seem a natural?
Marketing?
--
Robert Allen
r...@sun.com
Matthew Rapaport
In article <567k1m$d...@camel4.mindspring.com>, VT <v...@pipeline.com> wrote:
>gr...@earthlink.net (bob engnath) wrote:
>
>
>I think Matthew has inadvertantly hit on it - too many knives that we
>buy (the non-kitchen type) are made to please the "public" - yes, I am
>one. There was a great pursuit for TOUGHER knives that don't "break".
>
>So there was a surge toward THICKER stock at one time 1/8" was
>considered pretty thick and more than adequate for an outdoor knife -
>but 3/16" became the norm for "quality" knives, then even 1/4" for
>"real" men's tough tactical knives.
>
Which results in a thicker spine mainly since the blade is thinned out
by the hollow grind. Knife manufacturers thinkened the stock to
compensate for the weakness introduced by the grind. The result is an
easily maintained sharp edge, but with less efficient cut-through
capability.
>As Matthew points out we CUT with knives (and mostly DON'T PRY) -
>guess what? a nice THICK blade is NOT that condusive to a nice clean
>cut - because it now acts more like a cleaver/axe......
>
>I believe none other than our own Mr. AG Russell had something to say
>about thickness of knives - in his _advert_ on the AG Russell Deer
>Hunter and Bird & Trout models, at the URL:
>http://www.agrussell.com/russell/agdh.html
>
>His Deer Hunter 4" drop point model is from only 0.08" stock which is
>about 5/64" - just a shade over 1/16"!!
>
>The 3" drop point Bird & Trout model is only 0.06" which is 1/16" or
>just under.....
These seem to be specialized pieces of cutlery. Even a flat grind can
stand to be a little thicker than that. I would bet Mr. Russel's hunters
are *fantastic* skinners, but you probably wouldn't want to cut tent
stakes with them, and certainly not pelvic bone. No doubt they'd be great
slicing tomatoes though...
Rick Schultz
>
> In article <566j70$n...@venezuela.earthlink.net>,
> bob engnath <gr...@earthlink.net> wrote:
> >
> > Hollow grinding is the natural way to do it with automated machinery
> >where the billet is run between counter rotating grinding wheels. Most
> >mgrs. use automation, hence, they deliver hollow ground blades.
> > In the case of the Reeves knives. I would believe that Chris used it
> >grinding just about demands hand sanding.
> >gr...@earthlink.net
> >
>
Isnt it the other way around. All of the Benchmades I have seen have
V/flat ground blades, and the new Spyderco military is also v ground.
Many of the manufacturers use Berger or American Siepmann grinders (the
same grinders that the scissor manufacturers use). There are 2 grinders
to a set - each one identical to the other except that it is "mirrored"
or completely backwards to the other. One is used for the left side of
the blade and the other is used for the right side of the blade.
A fixture is used to secure the blank and then, a grinding wheel (one
per grinder) will be pushed into the blank, while another motor moves
the fixture (via a cam setup) away from the grinding wheel.
Then where does the V grind come from? These grinders use the SIDES of
the grinding wheel vs. the curved part of the wheel that custom
knifemakers use to put hollow grinds into knives.
For example, if you look at the MAD DOG series of knives, (refer to
Hilton Yams Ground Zero Knives web site for pictures) you will notice a
very straight blade transition line at the choil area. This is due to
the flat of the wheel is grinding the blade while the curved part of the
wheel is grinding the choil/blade transition line.
Some blades are deceiving....The Benchmade mini AFCK looks like a hollow
grind, but if you place a square or the flat rails of a dial caliper
against the grind, it is a flat grind. In fact, I heard Buck recently
bought some new state of the art Bergers (or was it Siepmanns?)
Hope this helps.
Rick
Mission Knives
Greg
Matthew Rapaport <m...@crl.com> wrote in article <5688j1$g...@crl.crl.com>...
> In article <566j70$n...@venezuela.earthlink.net>,
> less expensive to automate)? That makes sense. Yet I wonder, do other
> people find flat grinds more useful in every-day chores as I seem to
> do? This issue doesn't seem to be discussed very much.
>
> --
> matthew rapaport Philosopher/Programmer at large KD6KVH
Hmm IMHO it depends what the knife will be used for. Around the kitchen for
example a flat blade shines. In the woods a hollow grind is less to carry
and
it is easier to sharpen repeatedly. I've been using flat blades for diving
and they
work very well however I want to use hollow ground for a bit before I
comment
on them in the ocean. A well finished flat blade looks good, but the same
finish
on a deeply hollow ground blade really stands out. Turns out you pay your
money and you take your choice.
Greg
Les de Asis
Rick Schultz wrote:
> Some blades are deceiving....The Benchmade mini AFCK looks like a hollow
> grind, but if you place a square or the flat rails of a dial caliper
> against the grind, it is a flat grind. In fact, I heard Buck recently
> bought some new state of the art Bergers (or was it Siepmanns?)
>
> Hope this helps.
>
> Rick
> Mission Knives
Hi Rick! Benchmade just had a pair of Berger CNC BG-1 grinders
delivered and installed. They represent the most advanced blade
grinders available on the planet. We visited Buck knives this past
Wednesday and had a chance to tour their plant and they are using
Seipmann CNC grinders. They like them alot, they seemed very partial to
Siepmann and happy with them.
We made our decision based on our studies and material/design
requirements. We require capability to finish out tough materials and
challenging blade and resulting grind shapes and geometry.
Regards,
Les de Asis
Benchmade Knife Co., Inc.
Matthew Rapaport
In article <01bbd299$05536000$7a434acc@snake>,
Greg <sn...@bbs.annex.com> wrote:
>
>
>Matthew Rapaport <m...@crl.com> wrote in article <5688j1$g...@crl.crl.com>...
>> In article <566j70$n...@venezuela.earthlink.net>,
>> less expensive to automate)? That makes sense. Yet I wonder, do other
>> people find flat grinds more useful in every-day chores as I seem to
>> do? This issue doesn't seem to be discussed very much.
>
>example a flat blade shines. In the woods a hollow grind is less to carry
>and
>it is easier to sharpen repeatedly.
I can understand the second part of the last sentence, but not the first.
A flat ground blade does not have to be as thick at the spine to provide
equal over-all strength, and therefore can be about the same weight as
an equivalently strong hollow ground. One of the reasons flat grinds
shine in the kitchen is their thinner spines.
>Turns out you pay your
>money and you take your choice.
Ah, there's the rub! I wish it were so. Turns out, you can't get flat
ground knives as easily as hollow ground knives of equivalent quality
in the $25 to $50 range (folders). I wish I could afford more
than this for my day-to-day working knives, but alas...
--
matthew rapaport Philosopher/Programmer at large KD6KVH
john m.
VT wrote:
> The main "problem" I have with hollow ground is that too many knives
> actually THICKEN toward the edge -
>
> This is not such a big deal if all one does is shave hairs and score
> paper - ie: only use the edge and not have to cut through.
>
> But if you do cut through then that little bit of a hump does make a
> difference in a nice clean smooth cut.
>
> However if it is done right the hollow ground should be thinnest
> toward the edge -
Correct me if I'm wrong, but I think what you really want is a concave
grind. Isn't a hollow grind by definition slightly thicker right behind
the edge?
John
Hilton Yam
I thoroughly agree with Matt on this one. The thicker 1/4" blades are
meant for performing more than just cutting functions. While a razor
blade makes outstanding cuts, it is really lousy for chopping or prying.
Many will say that one shouldn't pry with a knife, but the reality is
that it is not always practical to carry extra tools with you. The
ideal field knife should then be able to perform more than one function.
If this concept were untrue, then that blows the whole Leatherman/SAK
multitool market. Specialized tools are great for specialized tasks,
but do not overlook the role of the multipurpose tool, even if it only
has one blade on it.
Hilton Yam
Ground Zero Knives
VT
"john m." <jmmon...@ucdavis.edu> wrote:
>John
You may be right - I have never seen a "definition" of hollow grind.
Hollow and concave seem to be interchangable.
I have used the term "concave" ground, in a post here, to distinguish
one which does not thicken toward the edge - I hope you are not merely
quoting me back at myself - (serves me right if you did :-)
In practical terms it would not be possible to easily distinguish
between one which thickens toward the edge and one which did not -
visually.
Short of using micrometers or precision calipers - the only way I know
is by feel - and that is not infallible.
So when I see a concave or hollow type of grind I do just call it
"hollow ground" - sorry if this annoys because of my imprecision -
I would really like to know HOW to tell the difference visually.
--
Vincent
v...@pipeline.com
VT
m...@crl.com (Matthew Rapaport) wrote:
>In article <01bbd299$05536000$7a434acc@snake>,
>Greg <sn...@bbs.annex.com> wrote:
<snip>
>>Turns out you pay your
>>money and you take your choice.
>Ah, there's the rub! I wish it were so. Turns out, you can't get flat
>ground knives as easily as hollow ground knives of equivalent quality
>in the $25 to $50 range (folders). I wish I could afford more
>than this for my day-to-day working knives, but alas...
Some of the finest folding knives ARE flat taper ground -
the Swiss Army Knife (SAK) -
_and_ they take and seem to hold a very fine edge according to both my
own experience, and other people's reports - at least on my Victorinox
SAKs.
The most expensive Victorinox SAK (other than the ones with built-in
watches) is only $57 at discount (the Swiss Champ) - so most of them
are under $50.
There are also the "non-traditional" SAKs - those bigger ones with the
locking blades. The Victorinox blades are the standard spear point
type 3-3/8" blade - 3-1/4" sharpened length - 4-3/8" closed. The
cheapest model is the Picnicker at about $20 discount.
I have the Hunter model cost about $27 discount - main blade, saw,
combo tool (screwdriver/caplifter/can opener/wire stripper) serrated
gut blade (hooked), corkscrew, reamer/awl, toothpick, tweezers,
keyring.
I think almost all Gerber folders are also flat taper ground.
Certainly their wonderful Bolt Action series are, as well as their
famous LST series.
Just to keep our Alvin happy - I think all of the traditional American
pattern folders like the Stockman and Trappers are FLAT ground too.
Case, Schrade etc make many traditional American patterns - many are
under $50 at discount.
--
Vincent
v...@pipeline.com
Jeffry Johnston
VT (v...@pipeline.com) wrote:
: Hollow and concave seem to be interchangable.
In my dictionary they are, but in an old Case catalog they are different.
: I have used the term "concave" ground, in a post here, to distinguish
: one which does not thicken toward the edge...
Do I actually have to agree with you? Or can I just leave it as is?
: ...the only way I know is by feel - and that is not infallible.
By feel is good enough.
I've only seen a couple CASE slip joint pocket knives that weren't hollow
or concave ground. One of the reasons they are better than others for me.
Alvin Johnston <--Libertarian