Thinning a western chef knife

[hibbs00]

Hey everyone. I have a wusthof chef knife that might need thinning sometime but I'm curious as to how you thin a chef knife without a shinogi line? A knife similar to the one pictured. Any tips or comments will be greatly appreciated. Is it just a lower angle than your sharpening angle? I can't seem to find any videos on YouTube about this kind of knife

 

[Benuser]

When it is a recent Wüsthof, you best start by removing the protruding shoulder which is almost 0.4mm thick. And change the straight bevels into convexed ones. OOTB, those edges end at some 13° per side, which this steel hardly takes and never holds with the first board contact. Turn it into some 18° per side, at least. You will notice deburring goes much better than with the initial edge. As you don't have to push those 0.4mm through dense food, a lighter touch becomes possible and the resulting board contact won't be that violent.
Don't even think about polishing the edge: the steel won't hold. I sharpen this steel on a Chosera 400. Perhaps the last deburring on a 800. JIS 600 and 1200. No way any finer.

 

[Heckel7302]

The most benefit of thinning is in the area about 1cm above the edge. Run it on a coarse stone with a very low angle, but not with the whole face flat on the stone. You can clean up scratches later with a sandpaper progression.

 

[hibbs00]

The most benefit of thinning is in the area about 1cm above the edge. Run it on a coarse stone with a very low angle, but not with the whole face flat on the stone. You can clean up scratches later with a sandpaper progression.

Ok so there's no exact angle or process? Just pretty much lay it flat and slightly raise the angle to thin it out? Do you go until you form a burr or do you still keep your edge how it is?

 

[refcast]

Hmm well, try sharpening at a slightly lower angle first than what the edge is first, get a burr at both sides, try the knife. If it gets stuck through food, use a lower angle again, don't necessarily need to get a burr, test the knife again

 

[Heckel7302]

Ok so there's no exact angle or process? Just pretty much lay it flat and slightly raise the angle to thin it out? Do you go until you form a burr or do you still keep your edge how it is?

I would not go until you form a burr. The steel won’t support that. You are just trying to reduce the thickness behind the edge bevel. If you have calipers I’d aim for 0.25 or so 1mm above the edge.

 

[myguidingmoonlight]

Not exactly as thick as a Wusthof but thinning the 1cm right above the edge is what I did to an Ashi I used to own. The geometry of the 1cm area right above the edge is important for performance. A small bevel also avoids me the pain of polishing too wide of a bevel.

 

[hibbs00]

I would not go until you form a burr. The steel won’t support that. You are just trying to reduce the thickness behind the edge bevel. If you have calipers I’d aim for 0.25 or so 1mm above the edge.

That makes more sense to me. If I don't have calipers just thin it down until it looks good? Thank you by the way. I know my knife is going to need it soon but doesn't have any other angle besides the edge. I didn't want to mess anything up

 

[hibbs00]

Not exactly as thick as a Wusthof but thinning the 1cm right above the edge is what I did to an Ashi I used to own. The geometry of the 1cm area right above the edge is important for performance. A small bevel also avoids me the pain of polishing too wide of a bevel.

Did that have a shinogi line or is that what you ground in yourself? Nice knife by the way

 

[myguidingmoonlight]

Did that have a shinogi line or is that what you ground in yourself? Nice knife by the way

It was like this before, full convex knife, though a bit thick for my liking.

The bevel I gave it is convex too, close to the original geometry, but thinner.

 

[hibbs00]

It was like this before, full convex knife, though a bit thick for my liking.
View attachment 296030

The bevel I gave it is convex too, close to the original geometry, but thinner.
View attachment 296031

Is that the same thing I would do to my wusthof?

 

[Benuser]

Is that the same thing I would do to my wusthof?

That's what you get when removing the shoulders, convexing the secundary bevels, thinning a bit more behind the edge and make all flush.

 

[Martyfish]

I have thinned a few cheaper western knives in the past using the process documented in the following link, including a Wüsthof Icon. It's basically a simple thinning guide that I made, which you might find helpful.



Here are a few pictures of the thinning process on my Wüsthof Ikon:

After Thinning

After Refinishing

Choil Shot Comparison (Pre and Post Thinning)

 

[GeneParmesan]

@hibbs00
I did a tutorial about the topic, once.
https://www.kitchenknifeforums.com/threads/tutorial-on-how-to-thin-european-knives.61403/

 

[tostadas]

Thinning on those softer steels doesn't take too long once you get past the bolster. You can also do a simple refinishing with sandpaper to blend away the scratches after. The level of final finishing you ultimately want can increase the time exponentially, but if your main goal is performance, it's not terrible. I do recommend getting a pair of calipers to help you understand what the edge geometry looks like, and how far you can push it.

 

[hibbs00]

@hibbs00
I did a tutorial about the topic, once.
https://www.kitchenknifeforums.com/threads/tutorial-on-how-to-thin-european-knives.61403/

Thank you! There is a ton of great information in there! Very much appreciated!

 

[hibbs00]

Thinning on those softer steels doesn't take too long once you get past the bolster. You can also do a simple refinishing with sandpaper to blend away the scratches after. The level of final finishing you ultimately want can increase the time exponentially, but if your main goal is performance, it's not terrible. I do recommend getting a pair of calipers to help you understand what the edge geometry looks like, and how far you can push it.

Luckily mine doesn't have a bolster. I have heard those can be a real pain. I'm probably going to give thinning a shot here in a couple days. I think I'll try with a cheap knife first just for the practice before going on to my wusthof

 

[Benuser]

Thank you! There is a ton of great information in there! Very much appreciated!

Be aware that the terms primary and secondary bevels are used here differently than we are used to.

 

[hibbs00]

I was wondering about that. Normally secondary bevel is the cutting edge right? Primary bevel is the taper?

 

[Benuser]

I was wondering about that. Normally secondary bevel is the cutting edge right? Primary bevel is the taper?

Here and probably only here, the secondary bevel is indeed part of the cutting edge, while the primary bevel is everything behind it, relief bevel, face or whatever.

 

[hibbs00]

Here and probably only here, the secondary bevel is indeed part of the cutting edge, while the primary bevel is everything behind it, relief bevel, face or whatever.

Oh I thought that's how it normally is. Primary bevel is the relief because that's the first bevel ground in when making a knife and cutting edge is secondary because it's after the relief. Learn something new everyday. Thank you

 

[Benuser]

Oh I thought that's how it normally is. Primary bevel is the relief because that's the first bevel ground in when making a knife and cutting edge is secondary because it's after the relief. Learn something new everyday. Thank you

You're most welcome! Thank you for the convincing explanation for our terminology. Poor thing, some very well known but somewhat voceferous makers aren't aware of it.

 

[hibbs00]

You're most welcome! Thank you for the convincing explanation for our terminology. Poor thing, some very well known but somewhat voceferous makers aren't aware of it.

I just have to remember now the cutting edge is the primary and the relief is secondary. I think I can do that lol

 

[Benuser]

Wait until you get familiar with asymmetry in Japanese knives, and the resulting different bevels on both sides. The notion of confusion will get a new meaning.

 

[cotedupy]

It was like this before, full convex knife, though a bit thick for my liking.
View attachment 296030

The bevel I gave it is convex too, close to the original geometry, but thinner.
View attachment 296031

That is a *very* sexy choil shot, I imagine it cuts like a dream now. Nice work!

 

[Heckel7302]

Seems like you've gotten more good advice. If you are at the point in your sharpening to want to thin, I would recommend picking up calipers. They aren't expensive. You want accuracy to 0.01mm. Here's one for $20

https://www.amazon.com/Measuring-To...3&sprefix=digital+caliper+0.01,aps,397&sr=8-4
They are useful for many things. For thinning, it's the best way to know how far you've gotten and if you are removing material evenly across the blade road. Also nice to be able to measure knives generally, spine thickness, overall geometry, etc. I use them to measure my stones too, so I can see if I'm wearing them down evenly. Very useful piece of kit.

For bevel terminology, I like to use primary bevel for the main geometry of the knife and edge bevel for the edge. Using secondary bevel just confuses things.

 

[hibbs00]

Seems like you've gotten more good advice. If you are at the point in your sharpening to want to thin, I would recommend picking up calipers. They aren't expensive. You want accuracy to 0.01mm. Here's one for $20

https://www.amazon.com/Measuring-To...3&sprefix=digital+caliper+0.01,aps,397&sr=8-4
They are useful for many things. For thinning, it's the best way to know how far you've gotten and if you are removing material evenly across the blade road. Also nice to be able to measure knives generally, spine thickness, overall geometry, etc. I use them to measure my stones too, so I can see if I'm wearing them down evenly. Very useful piece of kit.

For bevel terminology, I like to use primary bevel for the main geometry of the knife and edge bevel for the edge. Using secondary bevel just confuses things.

Thank you! I'll definitely get those. I like your terminology much better lol. Way less confusing. Thank you again for all the help. I'm really interested in perfecting my sharpening

 

[mengwong]

Have you got a loupe or a scope?

https://www.amazon.com/JARLINK-Illuminated-Jewelers-Magnifier-Foldable/dp/B078N34WZR
https://www.amazon.com/dp/B0CKHR2RNX

 

[hibbs00]

Have you got a loupe or a scope?

https://www.amazon.com/JARLINK-Illuminated-Jewelers-Magnifier-Foldable/dp/B078N34WZR
https://www.amazon.com/dp/B0CKHR2RNX

I don't. Are they actually worth it?

 

[stringer]

I don't. Are they actually worth it?

I would put money toward calipers, stones, knives, friends, family, charity, the lottery before a loupe or a scope. But some people couldn't do without them. YMMV.