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Salty dog

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[video=youtube;E7XTGYY4yE0]http://www.youtube.com/watch?v=E7XTGYY4yE0[/video]
 

Vertigo

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PUPPY!!!!!!!!


Edit - Oh yeah, simple and to the point video, thanks Salty!
 

Adagimp

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Another great video Salty. No frills, no non-sense, and respectfully informative.
 

chazmtb

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Great vid. How is the flex on the convex grind?
 

WildBoar

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Great video, Scott! One of my few issues with the reground pass-around was the sticking (especially when cutting horiz slices in onions)

This really shows the helpfullness of a convex grind + how well Del has been able to tweak his blades.
 
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Thanks for the vid, Salty. Haven't figured out why this is called a "convex" grind. It's a flat grind that's only taken part way up the blade instead of all the way up. Spoke with Del yesterday and he described how he ground the blade on the newer one.
 

Salty dog

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I guess I see convex as being like a hill. Up one side and down the other.
 

WillC

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Salty, thanks for the vid. do you find single bevel knives part food in the same sort of way? I've been flat grinding my knives so far and only convex the final bevel. I improved this a little by adding a 7 degree secondary bevel with a micro bevel primary. Do you think it needs to be convex to achieve this or could it have a partial flat grind, with a high secondary, then weeny little primary. Does the blending really change anything? I'm thinking if you have a high secondary it would be easier to maintain a tiny primary bevel as well, because you can rework the secondary at one angle.
 

Marko Tsourkan

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Scott,
how does Del's convex compare to Carter convex in terms of performance? Carter convexes his blades high. I think the last time I measured, it was 1.5" above the edge on 2.125" tall knife.


M
 

tk59

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1. do you find single bevel knives part food in the same sort of way?
2. I've been flat grinding my knives so far and only convex the final bevel. I improved this a little by adding a 7 degree secondary bevel with a micro bevel primary. Do you think it needs to be convex to achieve this or could it have a partial flat grind, with a high secondary, then weeny little primary.
3. Does the blending really change anything? I'm thinking if you have a high secondary it would be easier to maintain a tiny primary bevel as well, because you can rework the secondary at one angle.
1. Yes.
2. No.
3. It looks more "finished" and yes, to be able to "thin" the knife using the secondary bevel as a guide and then going to the primary bevel prevent a decrease in performance due to thickening of the blade behind the edge.

@Marko: Carter's bevels range anywhere from 1.4 cm to 2.5 cm in width. Del's heel area has excellent performance. He has been optimizing the balance of taper, secondary bevel angle/height toward the tip. I'm assuming that is why Salty is in the process of thinning down his bevels.
 

markk

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thanks for the video. well done and informative
 

monty

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I agree - no BS, just business. This has been helpful!!
 

apicius9

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I like the video, but the scientist in me does protest: Any thoughts about what part of the difference can be explained by the different grind and what by the different surface?

Stefan
 

JohnnyChance

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I like the video, but the scientist in me does protest: Any thoughts about what part of the difference can be explained by the different grind and what by the different surface?

Stefan
You mean does any of it have to do with one being straight steel and the other being damascus?
 

apicius9

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Yep, the knives are different in two variables, the grind and the surface. So if the taters stick differently, it can be because of either one or both. I have no idea, just curious.

Stefan
 

JohnnyChance

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The surface certainly can affect how food sticks, even on straight steel or clad knives, how it is finished (what grit finish, polished, scratch pattern, etc) has some effect. How much it affects it, and how much it varies from straight steel to damascus is probably negligible. I would say the grind is responsible for at least 95% of a blades food release performance, and finish 5% at the most. More so if we are talking a fully polished blade, but that makes it worse not better, so it isn't a good thing that it affects performance as equally (or whatever) as the grind does.
 

wenus2

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Yep, the knives are different in two variables, the grind and the surface. So if the taters stick differently, it can be because of either one or both. I have no idea, just curious.

Stefan
Wouldn't the scientist also expect the straight steel knife to stick more than the damascus one, given the uniformity of it's surface?
:scratchhead:
Perhaps this test actually shows how truly effective the grind is, despite being handicapped by a more "stiction" prone surface.


Good vid Scott, as always. Thank you for the insight. :thumbsup2:
 

tk59

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Yep, the knives are different in two variables, the grind and the surface. So if the taters stick differently, it can be because of either one or both. I have no idea, just curious.

Stefan
Del's deeply etched damascus actually releases food more readily than a more finely finished flat ground blade. If the damascus knife had been polished to the same level as the monosteel blade, Salty would have had a much more difficult time, getting those slices off.

Wow. I was slow on this one. +1 to both JC and wenus.
 

jason

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Scott,
how does Del's convex compare to Carter convex in terms of performance? Carter convexes his blades high.
M

The primary edge may be considered convex because of the natural rocking of the body while sharpening freehand, but Murray grinds his secondary bevels on a revolving waterwheel so his knives are hollow, not convex.
 

tk59

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That's interesting. I suspected as much until I put a straight edge to the bevel. It looks more or less flat although it is admittedly hard to tell. The "convex" Salty is referring to is the shoulder at the transition between the secondary bevel and the rest of the knife up to the spine.
 

jason

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That's interesting. I suspected as much until I put a straight edge to the bevel. It looks more or less flat although it is admittedly hard to tell. The "convex" Salty is referring to is the shoulder at the transition between the secondary bevel and the rest of the knife up to the spine.
I see. Any convex from the shinogi up is happening naturally from the forging process, I would say.
 

JMJones

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I am confused. Is the grind a partial flat grind that does not go to the spine or is the grind convex? Or something different?

Thanks

John
 

tk59

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Actually, I think he literally means the hump right on the shinogi.
 

JohnnyChance

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I see. Any convex from the shinogi up is happening naturally from the forging process, I would say.
Yes, forged knives often have "natural" convexing just from being hammered more in the middle of the blade. Sometimes they actually get thicker down towards the edge again from this, and their thinnest point ends up being in the middle of the blade (minus the actual cutting edge of course).
 

tk59

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I am confused. Is the grind a partial flat grind that does not go to the spine or is the grind convex? Or something different?

Thanks

John
Murray uses a large round stone to cut the partial "flat" ground bevel. Because the stone has a curved surface, it is actually a little concave according to Jason. To me and my straight edge, it appears to be roughly flat.
 

jason

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Murray uses a large round stone to cut the partial "flat" ground bevel. Because the stone has a curved surface, it is actually a little concave according to Jason. To me and my straight edge, it appears to be roughly flat.
I've ground all of mine to be full-flat, but if you were to lay the secondary flat on a rough stone and scratch it up a bit you'll see the hollow in the center - it may be minute on some knives.

@Johnny: The way Murray cold forges he'll hammer the outsides and then go up the middle to eliminate this as much as possible, but no one is perfect. ;)
 

Marko Tsourkan

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Jason,
do you have some kind of software running that notifies you every time Carter's name is mentioned? :)
Salty is a big fan of Carter's knives, so no worries here.

M

@ Scott,
so how does it perform compared to Carter?
 
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