Thinness, Stock removal thickness for kitchen knives

L

LukasFromGer

Joined
Jul 20, 2022
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18
Hi guys,

Im pretty new to knifemaking. I dont have a lot of space (just my apartment) or money, so I started with a file jig. While my first knife was okay (ignore the discoloration, I experimented with coffee) the knife itself is closer to an axe.
https://imgur.com/gXYaDIa
https://imgur.com/AeL91S4

I have now watched countless videos, read through threads here, german forums and reddit tried to find an answer which explains to me how to get a thin kitchen knife. Pretty much all the info is towards people who have the space and money for bigger machines, or are working on smaller EDC/hunting whatever knives. But my first knife, and now my second one both are kitchen knives...although closer to an axe than a thin kitchen knife.
Im using steel which is comparable to 1075. The stock is 3,5mm thick (0,137795"). I have bought a really cheap belt grinder to work on it quicker and easier. As far as I understand the easiest way is to make get a full flat grind which tapers towards the tip. Im trying my best, but its still closer to an axe.
https://imgur.com/a/EPSrbai

Should I have started with thinner stock? I got advised against that because the chance of warping will be higher. Whats the best way to get my knife thinner?

I just cant grasp how you guys buy such thick stock and make kitchen knives out of it. If I have to remove a lot of material now anyway, why not start with thinner stock?

Another problem then would, that pretty much every seller for steel stock Ive seen here in Germany sells only thick stock. Is there something Im missing or am I too stupid to grasp it?
 
The best way is to buy thinner stock and have it heat treated before you start grinding.
That will eliminate warps and get you on the right track for a better cutting knife.

If you are using only files etc. You're going to have a hard time, but it's not impossible.

If you're going to be using a small grinder with one speed setting, just be careful. Grind one pass, then dip in water, you don't want heat building up in the blade and ruining your HT.

Grind without gloves, with your thumb behind the area you are grinding. If you're thumb gets to hot, then you know you're getting the blade to hot and you need to dip.
 
Ah okay, I have bought ceramic belts, that should help I think?

So I buy thinner stock, cut out the knife blank and then heat treat it?
 
Carbon steel is pretty easy to straighten while tempering. I would recommend to partially file or grind the bevels before heat treating. It's a lot easier to do while the steel is soft if you are working with a small grinder.
 
Building up on that small table is also a good idea. Grinding with push stick will allow you to to put the pressure towards the edge and thin the edge. You shouldn't thin the edge too much until your final geometry is in place. Start with 2mm stock and make smaller kitchen knives (petty) until you get the grip of it. Use a marker between passes to understand better where you are removing material.
 
LukasFromGer said:
Another problem then would, that pretty much every seller for steel stock Ive seen here in Germany sells only thick stock. Is there something Im missing or am I too stupid to grasp it?
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There is dictum.de, they sell 80CRV2 in 2.35mm thickness. Maybe some of the guys from Europe can give you better recommendations.
 
H Hubert S. D DevinT
Well Im using a heat treat service by Schmiedeglut.de, heat treating myself wont be possible until I have my own garage or at least a little room for the tools. Im working in my living room right now

FredyCro FredyCro As far as I can see you need to have a big platen for your belt sander for the push stick "tactic"? What you mean is that I should make the little table for the belt sander bigger? Anyway, you are right that I should stick to petty knives. They seem a tad easier to thin and generally "produce". What exactly do you mean by dont thin until your final geometry is in place? Do you mean that I should taper first, and then thin/make the bevels? For the coloring, Im using special metal marking color

H Hubert S. Thanks for that, didnt really think of Dictum, Ill give it a look
 
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Also, grinding on those platens on cheap grinders is really shi**. Stick a piece of ceramic tile, hardened steel or fire glass on it and you should notice a huge improvement.

dtjqZX9.jpg
 
Yeah, you should upgrade to a bigger/sturdier table and add a platen (look behind the belt in my pic, there is a hardened steel platen added).

By thinning I mean that you do your bevels and taper, and still have lets say an edge that is 0.5 mm thick. Then by adding pressure to the edge of the bevel you start thinning the bevel keeping the angle you have previously ground in. Search on TBE (thickness behind the edge), for kitchen knifes a lot of people grind to 0.05-0.1 mm or to 0 and then sharpen back. The hardest part is to thin evenly and have on center bevel. You will need at least a good digital caliper to check your measures.
 
I have been working with 0.07inch 1084 and while I get a little warping on some of my blades, most of them are fine or within the range of fixability. When you start with stock as thin as that, it becomes difficult NOT to cut like a razor, even when your bevels are shorter than normal.
 
FredyCro FredyCro I'll take a look into it if I can attach something like that, seems useful enough. Do those people grind to 0.05-0.1mm before or after heat treatment? To be honest, Im not sure if I understand you correctly regarding the thinning of the bevels. I grind the bevels to lets say 0.5mm, and then grind them more until they are thin? I dont quite understand how I can thin the bevels that way.
I have a cheap digital caliper, and at the moment the edge is about 0.7mm thick, although Im not finished doing the bevels.

scarysamcary scarysamcary Thats hopeful. I'll try to find thinner stock, and try my luck :)
 
I grind only post HT, before HT you wouldn't want to grind much thinner then 0.5-1mm.

It's hard to explain, I might just confuse you more by trying to explain further with words. You want to twist the bevel toward the grinder, and put presure on it. When you work on the grinder you always look at the gap between the belt and the bevel, when raising the bevel you want to see a thin gap, when thinning a bevel you don't want to see any gap.
 
You can take advantage of having a thick stock by making a big step on the tang and the blade, I made some Japanese Gyuto myself, and personally, as well as feedbacks from other people I've talked to, a poorly done/fitted ferrule make the knife looks dirty, gunk and black stuff can get in there and is just un-appetizing. If you have a 3mm stock, then you can make the plunge area (not sure of the terminology) 3mm, and the tang 2mm, then you'll have a 0.5mm step on each side, and you can make a 2mm rectangular hole on the ferrule, making it a seamless fit, this would make the ferrule area looks way more professional and clean.
 
PMQ said:
You can take advantage of having a thick stock by making a big step on the tang and the blade, I made some Japanese Gyuto myself, and personally, as well as feedbacks from other people I've talked to, a poorly done/fitted ferrule make the knife looks dirty, gunk and black stuff can get in there and is just un-appetizing. If you have a 3mm stock, then you can make the plunge area (not sure of the terminology) 3mm, and the tang 2mm, then you'll have a 0.5mm step on each side, and you can make a 2mm rectangular hole on the ferrule, making it a seamless fit, this would make the ferrule area looks way more professional and clean.
Click to expand...
It is possible to get a good fit without the step. Here is an example of a petty knife with a 1.5mm thick blade I made a year ago and it does not have any dirt or gunk. Even on my not so well fitting handles, any small gaps are filled with color matched epoxy during assembly.

jz6Vpqn.jpg


The easiest/fastest method for me is to make a handle without a ferrule like in the picture below. I split the wood in half on the table saw, mill out a channel half the depth of the tang in either half and superglue the two halves back together. You have to look very closely to see the glue line and probably would not notice it unless you go looking for it.

un1wcvM.jpg
 
Hubert S. said:
It is possible to get a good fit without the step
Click to expand...
Yes, I totally agree, it is possible to get a good fit without the step, but IMO, it's easier to do because the tolerance on the tang hole doesn't have to be as tight, you can get away with less refined holes and the step will cover everything up, and you only need a carbide file guide.
 
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