Newbie question: chef knive has a negative curve, what to do?

[MarthaH]

Hi everybody,

after decades of using a Lansky sharpening system with more or less success I recently bought a dirty, but not much used Tormek 1200. It sat for a long time in a box with a lot of accessories. It ran, but after 10min the motor lost power. Since the Tormek construction is more than simple, the problem was easily identified: dead motor condensator. After replacing it, the machine is running fine.

Over the time I gathered quite a collection of kitchen knives. One of them, a Zwilling chef knive (20cm) is quite worn. The heel (is this the correct terminus technicus?) is longer than the blade, giving the knive a negative curve at the end.

What would be the correct procedure to repair this?

PS. English is not my native language, please be tolerant ;-)

[Dan]

Hello and welcome to the forum.
Is the blade worn something like this?
https://c8.alamy.com/comp/BPWKJC/an-old-chefs-knife-which-has-been-sharpened-until-the-blade-is-worn-BPWKJC.jpg
It would be useful to see a photo of your knife to be able to advise you better.
"A picture is worth a thousand words" as they say...

Danny

[RickKrung]

Hello and welcome to the forum.
Is the blade worn something like this?
https://c8.alamy.com/comp/BPWKJC/an-old-chefs-knife-which-has-been-sharpened-until-the-blade-is-worn-BPWKJC.jpg
It would be useful to see a photo of your knife to be able to advise you better.
"A picture is worth a thousand words" as they say...

Danny

Yes, or what is sometimes referred to as a "Bird's Beak", like this.

[MarthaH]

Meta question: how can I upload an image? Other forum software allows to upload pics and insert them in a posting. The software asks for an URL, but the pics are one my harddisk?

M.

[HaioPaio]

Have a look here

[MarthaH]

I don't have this options under the entry window, only "Shortcuts: ...". Maybe new members can't upload pics?

Anyway: my knive looks similar to the example in posting #1 from Dan.

[Ken S]

Welcome to the forum, Martha.

If you hold your knife on a cutting board, looking at it from the side, you should not be able to see light under any part of it. If you do, you need to correct it. The area where the light shines through will not cut through properly. In English, we call this "the green onion effect". This is usually caused by the bolster of the knife protruding below the edge of the blade. This is corrected by grinding down the bolster. This should be checked and corrected as part of routine sharpening, although it is frequently overlooked. This can be done freehand. Wolfgang covers this in one of the advanced knife sharpening classes.

Please let us know if this does not correct the problem. We are here to help.

While you are reading this, may I ask a favor? Although I am a US native English speaker, I have some long ago background in Spanish and German. I am sensitive to the frustrations our members who are not native English speakers may have on the forum. The forum has grown from a primarily US based English speaking community to a much more global community. I welcome this growth, although it also brings some "growing pains". I  would welcome any suggestions you might have to make the forum more multilingual friendly. You may post them or send mea Personal Message

[MarthaH]

Welcome to the forum, Martha.

If you hold your knife on a cutting board, looking at it from the side, you should not be able to see light under any part of it.

This implies that the cutting part of blade is straight. Usually it is curved, but I think you want to say it should touch the board at one point only (this being the lowest part of the curve). If you have two points, the blade curves away from the board between the two contact points.

That said, how do I remove the excess of material towards the grip? I found a video on YT where someone repaired a similar knive by grinding away the excess metal with a belt sander before grinding the blade. I don't have a belt sander, can I use the standard (coarse) Tormek stone for this?

M.

PS. I now can add pics, this is the knive I want to sharpen.You cannot view this attachment.

[MarthaH]

While you are reading this, may I ask a favor? Although I am a US native English speaker, I have some long ago background in Spanish and German. I am sensitive to the frustrations our members who are not native English speakers may have on the forum. The forum has grown from a primarily US based English speaking community to a much more global community. I welcome this growth, although it also brings some "growing pains". I  would welcome any suggestions you might have to make the forum more multilingual friendly. You may post them or send mea Personal Message

I've been around discussion boards from the early days of the internet (usenet...) until today (I got my first permanent (!) connection from my home to the net in 1995, with superfast 64kb/s...) English is by now the "lingua franca", and nearly everybody (with some technical background) is more or less fluent in it. My native language is German, and there are german speaking boards about knives and grinding them. However, I feel discussions there tend to turn into esoteric regions with more or less connections to the real live. I read through several threads here and think the contributors here are a little more down to earth. I appreciate this approach ;-)

It is not easy to fill a board with lively discussions in several languages. Anyone who is into a technical/practical hobby like this should at least be able to follow the topics in english, so no direct advice from me. One could however keep a list of native speakers somewhere in this board to have someone to talk to if the language capabilities are not precise enough.