Advice sharpening an 8" chefs knife

[Andrew]

Hi,

I’ve just started getting familiar with my WE. Diamonds up to 1000. Fine for what I use it for. Kitchen knives.

Been breaking them in, bought cheap knives. Usual beginner familiarities to overcome. I remember watching a video Josh did on finding the sweet spot where he used what looked like masking tape, drew a line parallel to the knife edge. Was very informative. It naturally works well for small and pairing knives.

What I noticed when you clamp an 8″ chefs knife, the angle’s fine in centre but get a bit of belly towards heel and tip as the angle changes. Do you need to do these knives in 2 stages of clamping or do you just do as is and get on with it? Even with the belly the knife will be wickedly sharp. Hope belly is the right terminology. Even if it wasn’t I know you’ll all know exactly what I mean. Read a mountain of posts. There’s some familiar names keep cropping up.

What would you recommend?

Cheers

[tcmeyer]

Hello Murdock:

Yes, the belly of the knife is technically the center of the arc as it sweeps from the main edge up to the tip.

Assuming that the “belly” you describe is a convex sweep near the heel, that’s probably a result of the technique you use – how you hold the stones and how much pressure you apply and where.

For a chef’s knife a convex belly there isn’t all that bad.  The chef will “rock” the edge anyway as he makes his cuts and chops.  A concave section there, however, would be bad – rendering that section of the blade ineffective, as it would not contact the cutting board.

No, you shouldn’t have to do an 8″ chef’s knife in stages and the angle shouldn’t change significantly from heel to tip, certainly not enough to create a “belly” as I think you describe.  If you had a blade whose edge followed the sweep of the stone along the same line taught by Josh, the bevel angle would be constant.    Where an edge is parallel to the base – effectively a straight line located above the vise – the bevel angle will also be constant,  In the case of the constant arc, the path of the stone is conical.  In the case of the straight line, the path of the stone is on a single plane.

I think you’ll be OK, but you may want to work on your hand technique.  Let the face of the stone follow the edge, and apply moderate pressure with the tips of your thumb and index finger directed at right angles against the plastic edges of the block.  I recommend holding the block near the bottom.  Among other things, this will weaken your influence on the angle of the stone, letting it follow the edge more naturally.

[Mark76]

I also don’t understand exactly what the problem is, but if you experience wider bevels towards the tip, you’re probably looking for the sweet spot. There was recently a topic on this: URL

Molecule Polishing: my blog about sharpening with the Wicked Edge

[Andrew]

Thanks Guys. I’ll persevere with what I know will be poor technique on my part.

I’ve watched quite a few of Josh’s videos which I have found very useful. So Kudos to Josh for the time he has taken to create them.

I’ve also ordered a usb microscope. Watched tom’s video there. That will work for me. Also good to hear you can do an 8″ inch knife while being clamped in one position.

I know I could persevere with the kit I have but chose to get the upgraded arms. Don’t get me wrong the sharpness I get already is……wicked, but will enjoy the increased accuracy and fluidity of the new arms. Once they come I’ll get some serious stone breaking in and edge wickedness.

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CliffCurry

[Geocyclist]

Mark76 wrote:

I also don’t understand exactly what the problem is, but if you experience wider bevels towards the tip, you’re probably looking for the sweet spot. There was recently a topic on this: URL

I think what he is asking is the heel gets a little more acute because 8″ is so long.  I usually clamp mine about in the middle.  The tips of my chef’s knives are pretty straight so while this is not the perfect setup for getting the sweet spot at the tip it comes out pretty good.  Because I clamp in the middle the very heel is a little more acute than the middle of the knife, but not bad.  If I clamped closer to the tip I could perfect the sweet spot i theory, but the the heel would be worse.

I theory you would want 2 setups but I don’t think it work very well in practice – even blending in the middle, over sharpening of the middle, and you would have to clamp twice for every stone since you can’t finish one half then start the other half with a  rough grit.  By “in theory” I mean you could sharpen a very long sword (if the weight was supported) by moving it 6 inches at a time, but in reality it probably wouldn’t work too well.

In the end I accept less than perfection on kitchen knives since they getting dull so quickly anyway.

[Andrew]

I’m pretty much feeling the accept less than perfection bit. I just ultimately want sharp knives. Even if the tip has a slightly wider bevel I guess that’s ok. At least you know you can clamp and touch up your edges and have ultimately sharp knives quickly.

I’ll see once the upgrade arms come and I can get some serious amount of practice. The usb microscope I’m getting is since I’ve not succumbed to the imminent fact that I’ll need to start wearing glasses. small detail close up gets fuzzy. I really need to get those eyes tested and accept that I need a pair of specs. Oh well, comes to us all

[tcmeyer]

When you get to about age 44, the old age truck comes barreling down the road at you and the first thing you’ll need is bifocals.  Trust me, that won’t be the last you’ll see of that truck.

There’s an important thing you need to understand about the conical and parallel situations I described above. A chef’s knife typically has a long straight section between the heel and the belly.  Along this straight line, it doesn’t matter where you place it relative to the vise – if it’s parallel, the angle will be constant.  The rest of the edge is made up of a sweep along the belly toward the tip.  If this belly is positioned so the edge more or less follows the conical sweep of the stones, the angle will be more or less constant throughout that sweep.

This all means that you should position the belly of the edge using Josh’s method of marking the tape on the stone and matching it up to the sweep of the edge.  Don’t worry about the straight section, because it simply doesn’t matter where it falls, so long as it stays relatively horizontal.

And you’re going to love the USB ‘scope and the micro-adjusts.

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CliffCurry

[Andrew]

Thanks Tom

I primarily bought the upgrade arms for the micro adjusts. That appeals to my inner perfectionist. The usb makes up for what the truck is trying to destroy. Although the eye test is looming. Yes age 47. Held out as long as I could, but the truck’s going to win this one.

Your description with Josh’s taping method makes a lot of sense. I’d only seen a demo on a short knife and the taped mark followed the edge from heel to tip, but naturally with a longer knife it doesn’t follow the edge the same as it did in the video, but now I know to make it follow the belly to the tip this way following the conical curve.

 

1 user thanked author for this post.

CliffCurry

[Author]

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