Grinds

David Martin

David Martin

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Is conical grind the same as a flat grind?
I'm asking this because I'm seeing this wording on knife descriptions from companies that traditionally do flat grinds. Thanks, DM
 
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I suspect a computer geek is writing the knife descriptions but is a novice knife guy. DM
 
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jpm2 said:
I’m also curious how conical can apply to a knife grind.
Click to expand...

If the blade has a constant edge curvature and the blade face is flat ground perpendicular to the edge at a constant angle I believe the primary grind will form a conical frustum. That would be a rather peculiar case I think however.
 
i.e. - a frustum= the part of a cone formed by cutting off the top parallel to the base. This is not what we're talking about... From Webster's ditionary. DM
 
Heck if I know.
I just totally reground the blade on a Ti Lite IV.
I went down to one mm at the spine but kept the middle part of the side of the blade thicker; it's about 2.5mm right now. I will probably take it down to 2mm soon I just ran out of time last night. Once that's the way I want it I will thin it out behind the edge a bit and make it have a consistant finished look.

The idea is this kind of blade might tend to cut curves in say thick leather or card board better than a full flat ground knife. I was curious so I decided to try it. The cross section is roughly an oval. My first "convexed" knife.
 
David Martin said:
Is conical grind the same as a flat grind?
I'm asking this because I'm seeing this wording on knife descriptions from companies that traditionally do flat grinds. Thanks, DM
Click to expand...
Hi,

Considering these following descriptions , i think they mean round/convex ... like you get from a conic section, it helps with potatos





Professional conical grind on the full length of the blade, as well as crosswise.
This unique taper grinding provides optimum edge shape for sharpness and minimal resistance while cutting.


AV grinding machines are made for flat or conical high precision grindings in knives, forged knives, all types of scissors, gardening tools, sabers, swords or hand tools.
The grinding process involves passing the workpiece to be rectified by the side face of a grinding wheel (ring-shaped ) to produce a flat or a conical grinding. Grinding parameters (wet grinding) are easily programmed by a CNC depending on the geometry of the workpiece.

Las máquinas amoladoras serie AV están concebidas para efectuar rectificados planos o cónicos de alta precisión en cuchillos, cuchillos forjados, tijeras de todo tipo, herramientas de jardinería, navajas, sables, espadas y herramientas de mano.
El proceso de amolado consiste en hacer pasar la pieza a rectificar por la cara lateral de una muela abrasiva (con forma de aro), para producir en dicha pieza un rectificado plano o cónico a lo largo de la misma. Los parámetros del rectificado (amolado) se programan fácilmente mediante un CNC, dependiendo de la geometría de cada pieza.


Hollow grinding machines (double side) series SV are designed to make high precision concave grindings for cooking knives, sport knives, flick knives, swords and hand tools.

Las máquinas vaciadoras (doble filo) serie SV están concebidas para efectuar rectificados concavos de alta precisión en cuchillos de cocina,cuchillos deportivos, navajas, espadas y herramientas de mano.





It helps with potatos

Potato slicing : full flat, convex, convex-flat (ontario grind), granton, "speed holes"
Potato slicing : full flat, convex, convex-flat (ontario grind), granton, "speed holes"
Cliff Stamp
Cliff Stamp
6.7K
4,903 views
Published on Oct 25, 2012

The intention here was to film with two camera's and then play around with zooming and picture in picture to do close up's of the cutting. Unfortunately the camera with the full pan view borked on the memory card so it didn't record.

In any case it is fairly obvious that a few things can be noted the first being you need to cut a decent few types of potato as there are differences due to moisture and starch/sugar content. General observations :

-a full flat grind will stick light to moderate in general
-a very light semi-convex (the chinese cleaver) will start to separate
-a full convex (higher curvature) will be very free
-grantons and speed holes do little to nothing

In regards to how much of an arc you need, as a general rule, if you look at it and can actually see the convex bevel (and you are not Kyley Harris) you have more than you need.
 
Wizard, ok, "the blade face is ground perpendicular to the edge". I got that, if you leave off frustum. To read, ' to form a conical edge'. This
would seem to be correct for a convex edge at the bottom of a flat ground blade. DM
 
B bucketstove , yes. Thank you for including this in both Spanish and English. They were both good.
A long secondary bevel on a full flat ground blade... The secondary bevel has it's shoulder rounded at the top. Thus, a convex secondary bevel. Not a zero grind. I can duplicate this cutting test on another full flat ground blade I have on a worn sabatier. Thanks, DM
 
To me it sounds like they're using improper terms to try to describe a distal taper. Many culinary knives are distally taper-ground in addition to from spine to edge, as is conventional. This means that the blade is tapering along two axes rather than just one.
 
David Martin David Martin I was thinking of the primary grind, rather than the edge bevel. Also to be clear I wasn't proposing that this is what they actually meant which is why I wrote "a rather peculiar case." I was only describing one way for the primary grind of a blade to be in some manner conical. To illustrate, in case it wasn't clear, consider a circular blade (fig. 1). If the grind is flat then it is a portion of a cone, specifically a conical frustum. If one were to cut a more typical knife blade from this (fig. 2) the grind would still be a section of a cone.

Figure 1
YhLivt1.jpg



Figure 2
7LSaFF2.jpg
 
B bucketstove , we don't have a sabatier with a granton edge. But we do have 2 sabatiers with 2 different edges. One is a L.C.Germain w/ a 8 1/8" blade ffg with a V grind edge that I trimmed down the shoulder creating a convex edge and it is a worn blade. The second sabatier is a Buck w/ a 8 1/4" blade. It has a hollow grind at the last 5/8" of its flat ground blade. I gave it the same V grind, freehand but did not trim the shoulder. I sharpened both blades on a IB-8 fine India and removed the burr on the stone. No stropping. My wife will cut the potatoes and I'll watch & not school her. I'll be back w/ the results. DM
 
Ok, here's the results. She did not see the video, just me. I merely showed her how to duplicate the cut. Then I watched. Afterward I even
tried it myself and got the same results. With the L.C. Germain a ffg one side or the other the potato stuck onto it at each cut. Doing it with
the Buck w/ the lower portion of it's blade a hollow grind, the potato never stuck to it. The hollow grind makes it release at the bottom and
when you lift the knife the potato stays put. Both blades were quite sharp and it was hard to tell any difference in how they penetrated during the cut. Maybe the Buck was a touch better. Still, I think it was because of that lower portion being hollow ground. DM
SabatierSlices.jpg
 
bucketstove said:




It helps with potatos

Potato slicing : full flat, convex, convex-flat (ontario grind), granton, "speed holes"
Potato slicing : full flat, convex, convex-flat (ontario grind), granton, "speed holes"
Cliff Stamp
Cliff Stamp
6.7K
4,903 views
Published on Oct 25, 2012

The intention here was to film with two camera's and then play around with zooming and picture in picture to do close up's of the cutting. Unfortunately the camera with the full pan view borked on the memory card so it didn't record.

In any case it is fairly obvious that a few things can be noted the first being you need to cut a decent few types of potato as there are differences due to moisture and starch/sugar content. General observations :

-a full flat grind will stick light to moderate in general
-a very light semi-convex (the chinese cleaver) will start to separate
-a full convex (higher curvature) will be very free
-grantons and speed holes do little to nothing

In regards to how much of an arc you need, as a general rule, if you look at it and can actually see the convex bevel (and you are not Kyley Harris) you have more than you need.
Click to expand...
Knives on that video lift half potato :eek: :D Sorry guys , there was only two existing knives that really don t stick to potatoes and both are mine :p And here is the proof :D
 
David Martin said:
Ok, here's the results. She did not see the video, just me. I merely showed her how to duplicate the cut. Then I watched. Afterward I even
tried it myself and got the same results. With the L.C. Germain a ffg one side or the other the potato stuck onto it at each cut. Doing it with
the Buck w/ the lower portion of it's blade a hollow grind, the potato never stuck to it. The hollow grind makes it release at the bottom and
when you lift the knife the potato stays put. Both blades were quite sharp and it was hard to tell any difference in how they penetrated during the cut. Maybe the Buck was a touch better. Still, I think it was because of that lower portion being hollow ground. DM
View attachment 1126228
Click to expand...
This ....don t stuck to potato :)
2mm on spine 1.2519 steel on 63-64 Hrc , deep hollow grind only on one side other side is flat ......
rQ1d5Jm.jpg

vCPCRzA.jpg

fJ5CIeN.png
 
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Look this picture , see where is that juice on blade from potatoes ? That s the point where the potato make first contact with this blade ...except edge of course
NPug9lR.jpg
 
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Nat, good job on the knives. I think if you did a longitudinal cut like Cliff did the results would be the same. Thank you. I've not used a knife with that type grind but I can see why it would work well on vegetables.
Perhaps my L. C. Germain sabatier would have preformed better if it had a more pronounced convex grind. Cliff Stamp didn't have knives like these in mind when it did his test. I'm not trying to cast a shadow on his test. I'm merely doing the test with different knives and giving my results. I think he draws a valid conclusion about the granton grind. DM
 
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