Secondary bevel on a Kiridashi?

Natlek said:
I do not understand . . . . IF the bevel is a single bevel to zero edge then that is chisel grind , right ? If you sharpen that bevel from both side it is no more chisel grind .................it become classic V grind ???
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Well, yes .. and no.

True, to the purist it no longer has a single bevel to a zero edge.

But, there is nothing in katakiri-ha that says there can't be a tiny secondary bevel to strengthen the edge. In most all cases I know of, there IS a minute secondary on the chisel grind. Without it, the edge would not hold up well because the angle will be far too low. In a 3/16" thick blade with a 1" high bevel the edge angle is less than 10 degrees. On a 1/8" thick blade is is 7 degrees.
Most every single edge tol has a micro bevel added. Sometimes it is merely a hand stroke on a extra fine stone at a higher angle. In many cases, the secondary micro-bevel can't be seen without a magnifier. I would not call that a "Classic V grind".
Gravers have the extra "facet" for the same reason ... the edge/point would chip off almost immediately without it.

I would only put the secondary on the main bevel side, not the back. This is because if there is a chip you will have to take the whole back down to flat in the repair. With the secondary on the front, you can do what most folks do and just re-do the secondary until the chip is gone. If the secondary becomes too large eventually due to many sharpenings, then you can take down the entire main bevel to zero again. In all sharpening of chisel edge blades (katakiri-ha), the back is lightly polished to remove any rolls at the edge, but should never be given a secondary. I don't use an exact angle, but I would say the micro-secondary is between 15 and 20 degrees for most kitchen knives.
 
googlebutt said:
Completed my first Kiridashi (second knife as well).. These little bevels really are trickier than they look! I'm super happy with how the acid stonewash turned out, and I definitely acknowledge that I didn't really sand well enough (note the big ass scratch on the bevel). At any rate, I'm happy with it and I'll be making more. I think I might stick to making simple small knives like this for the next few.

A side note, after playing around with it, I understand and agree with J joedhiggins 's comment about this style of knife wandering when doing a freehand cut.
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The finish on the knife looks good. I would polish the primary bevel as well after the wash. I think it would look better. It is possible to cut with a single bevel without wandering, but you need to rotate the knife to bisect the edge. It is awkward and not particularly conducive to freehand cuts in most situations. From a culinary standpoint, single bevel knives are most useful for cutting a thin slice off of a firm food. The backing of the cut can work like a fence while the thin slice slides away. Other than that, getting straight cuts is generally a lot more ergonomic with a dual bevel knife.

AVigil said:
Correct,

It gives the appearance of a chisel grind but it is not.
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I agree this this partly, it is definately not a standard "V" grind afterwards. The cutting edge will have a larger included angle, but the knife will still want to wander. If you only microbevel the flat, you will have a hard time telling the difference between it and true chisel grind. The two things a chisel grind give you are a smaller included angle edge (potentially) and asymmetric cutting forces. There isn't much difference in the cutting performance of of a couple degrees of included angle, It is actually the thickness of the knife behind the edge that makes a bigger difference. Saber, chisel and scandi grinds tend to be thick behind the edge. As such, when cutting a stiff material, they will require a lot more cutting pressure than does a low angle FFG to say .002-.004 prior to the bevel. Making very shallow cuts or cutting flimsy material, you won't notice. THe best example I can think of this is using a chisel to make a mortise, a vertical cut will deviate to about 1/2 of your included angle. So a 30* chisel grind hammered vertically into a peice of wood will make a cut somewhere 15* off vertical, depending on the grain orientation.
 
I think you have that last part wrong, Joe.
If you drive a chisel into a piece of wood near the end, it will cut a straight line and push the chip off from the bevel. If you drive a V grind into a piece of wood, it will go straight down, and pop the chip off, but would not make a vertical cut, If this was done in the middle of a board for a mortice, the hole would end up with angled sides from the V grind tool, but straight sides from the chisel grind.
What I am saying is the flat side goes straight down in the wood. Obviously, if you used the chisel backwards, you would get an improper cut.

A V grind is better for general use cutting because it has no cut side direction. A chisel grind is better for … chiseling … because it has a dedicated direction of cut. In a knife like a kiridashi .. of a yanagi-ba … the dedicated cutting edge creates a perfect slice with lower resistance.
 
Stacy E. Apelt - Bladesmith said:
I think you have that last part wrong, Joe.
If you drive a chisel into a piece of wood near the end, it will cut a straight line and push the chip off from the bevel. If you drive a V grind into a piece of wood, it will go straight down, and pop the chip off, but would not make a vertical cut, If this was done in the middle of a board for a mortice, the hole would end up with angled sides from the V grind tool, but straight sides from the chisel grind.
What I am saying is the flat side goes straight down in the wood. Obviously, if you used the chisel backwards, you would get an improper cut.

A V grind is better for general use cutting because it has no cut side direction. A chisel grind is better for … chiseling … because it has a dedicated direction of cut. In a knife like a kiridashi .. of a yanagi-ba … the dedicated cutting edge creates a perfect slice with lower resistance.
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Stacy, I think we are saying the same thing in different ways . And we use a chisel grind because in practise we don't just bash a chisel vertically into a piece of wood. When we relieve one side of the vertical cut (hollow out the material that will for the hole for our mortise), the chisel will tend to follow the vertical, non beveled face as it plunges. If we tried to do the same without relieving the material from the mortise first, we wouldn't get a vertical wall. I dont have the ability to draw a picture here, but doing this would be very similar to what you would get if you had a V grind that you whacked into the wood vertically. The wall would be a touch straighter, because the impulse of the chisel is initially vertical, but it would look very similar.

I guess I should have said that if you were to try to cut the mortise walls before relieving the center, you would get that wandering cut. Ultimately it may have been a bad example, at least without a picture.
 
I almost said, "I think I agree with you, but .....".

Yes, we are saying the same basic thing. Both grinds have their uses.


Just for info, to make a blind mortise for a tenon in a board/log, you first drive the chisel about 1/4" deep to set the profile, with the flat to the perimeter. Then you turn the chisel 180 degrees and make a second set of cuts about 1/2" inside the perimeter cut. Turn the chisel 90 degrees ( sideways between the two lines) and work around the "track", popping the chips between the two lines. Repeat over and over to make a straight sided mortise as deep as needed.
 
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Or, if you can, use a mortising machine or forstner bits to hog out the bulk and trim with a mortising chisel. Hand cut mortises are more of a pain for me than they are Paul Sellers. I can get them looking good, but I can't do them as fast as he does.
 
Yes, I was talking about the old school way.

Today, most folks drill a center hole and then use the chisel, or if you have modern equipment, a mortising machine.

You have to give a lot of respect to the old guys who chiseled dove tails, mortices, and rabbits that were so tight they didn't need glue.
 
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