Hook and S-ground knives

[Sushiman703]

Recently switched over to belt sanders from stone sharpening
and always questioned how do people get those s grinds or even hooks on the knife. Do I need additional equipment or special technique? I know i won't even attempt such a high level task but always wondered. Thanks kkf!

 

[HumbleHomeCook]

"S" grinds are achieved during the making of the knife, not after.

 

[MSicardCutlery]

S-grinds are really just hollow grinds that don't terminate at the edge. They're cut using a radiused platten, or a large contact wheel. Hook grinds are a little more complicated. See this post: Food Release: Stiction and the Grind for a demo of how they are made.

 

[TB_London]

Get a big wheel or radius platten and a blade blank
Then start to hollow out the moddle

Here a 12” wheel is being ised

As you grind use thickness gauge to make sure you aren’t going too thin, you don’t want to break through the middle.
Once you have it where you want it then add in the edge bevel of the preferred geometry

Then once it’s roughed in carry on and tidy all the grinds up so they’re neat and finish as usual.

You can then experiment with placement of the hollow higher or lower, radius, etc

Or you can go hi tech and mill out the recess

 

[user 51158]

Like mentioned above, eather way go for a big contactwheel or a radius platen.
If you ever looking for a radius platen custom made for your machine just sent me message.
I make them in two sizes 14” and 29” radius.

Working on a s-grind myself now aswell with a 12” wheel:

Here is an example of the radius platens i make:

 

[Sushiman703]

Do I need a jig to use a radius platen or can I try to freehand it?

 

[RRLOVER]

Everyone has given great advice...My advice is to practice on some mild steel before you try it on a heat treated blade unless you want your "Pile of Shame" to be very large.

 

[MSicardCutlery]

Do I need a jig to use a radius platen or can I try to freehand it?

You can do either. Having a work rest is easiest. Freehanding isn't that bad if you've had a little practice.

 

[Sushiman703]

Yes thank you all for the advice and knowledge! I know I shouldn't rush these things but I just got into it and it's just so exciting

 

[sansho]

S-grinds are really just hollow grinds that don't terminate at the edge. They're cut using a radiused platten, or a large contact wheel. Hook grinds are a little more complicated. See post #307: Food Release: Stiction and the Grind for a demo of how they are made.

it's possible to link directly to a post. copy the link from the date, the post number, the share button, etc.

https://www.kitchenknifeforums.com/threads/food-release-stiction-and-the-grind.35641/post-969121
referring to post numbers is bad because post numbers can change for a variety of reasons. it's also inconvenient to hunt around for a post manually.

 

[MSicardCutlery]

Edited

 

[Pie]

Someone was going to sandpaper some concavity into something a few years ago.. I wonder how that turned out.

It’s viable theoretically but seems like a bit of a challenge without a rig or something to maintain consistency.

 

[ian]

Someone was going to sandpaper some concavity into something a few years ago.. I wonder how that turned out.

It’s viable theoretically but seems like a bit of a challenge without a rig or something to maintain consistency.

Heh prob a bunch of people have tried that, including me. It works, but it’s slower than using a grinder. IIRC, @RDalman has used (infrequently) an alternative to his usual contact wheel setup, where he has some handheld device to which he can attach EDM stones, and then he manually scrapes in concavity.

 

[deltaplex]

Someone was going to sandpaper some concavity into something a few years ago.. I wonder how that turned out.

It’s viable theoretically but seems like a bit of a challenge without a rig or something to maintain consistency.

You can make a sanding jig for it, but I'd probably just convex some spare low grits stones/work with SiC stones that were already convexed for the heavy lifting.

 

[RDalman]

Heh prob a bunch of people have tried that, including me. It works, but it’s slower than using a grinder. IIRC, @RDalman has used (infrequently) an alternative to his usual contact wheel setup, where he has some handheld device to which he can attach EDM stones, and then he manually scrapes in concavity.

Actually no on that. I used them for finishing after coarse grinding on the grinder only for a while.

 

[ian]

Actually no on that. I used them for finishing after coarse grinding on the grinding only for a while.

Ah, I misunderstood.