- Joined
- Feb 29, 2016
- Messages
- 26
- Reaction score
- 18
These guys have been putting out good livestreams and sharpening videos. Worth a look: https://youtube.com/c/KnifewearTelevision
question about a sharp knife that cant cut tomatoes well
- Thread starter r0bz
- Start date
Help Support Kitchen Knife Forums:
How does knowing the exact knife or HRC or touching the edge change anything? The dude says he can’t slice tomato after the 8k- either get better at the 8k (takes time and effort- something to keep trying as you learn over a period of time) or for now just leave it at 800g which works fine.
Yeah we can all debate intricacies of steels and hardness and stone progressions- but that’s like trying to explain to someone how water expands when it freezes to someone that bursts their water bottle when they put it in the freezer, or asking them for the brand of bottle and type of water when the simple answer is to not fill it all the way up before putting the lid on. (Btw water expansion when moving from a liquid to solid phase is more complicated than it seems!)
OP- it’ll take practice to get a good edge on a high grit stone. Don’t worry about it, enjoy the sharp edge off the coarser stone and keep practicing. If it doesn’t cut a tomato off the high grit go back to the coarse grit until it does.
Yeah we can all debate intricacies of steels and hardness and stone progressions- but that’s like trying to explain to someone how water expands when it freezes to someone that bursts their water bottle when they put it in the freezer, or asking them for the brand of bottle and type of water when the simple answer is to not fill it all the way up before putting the lid on. (Btw water expansion when moving from a liquid to solid phase is more complicated than it seems!)
OP- it’ll take practice to get a good edge on a high grit stone. Don’t worry about it, enjoy the sharp edge off the coarser stone and keep practicing. If it doesn’t cut a tomato off the high grit go back to the coarse grit until it does.
Nah man. Yes, to enjoy the edge of the course stone and specialize there. But the steel does matter. It's a waste of time putting soft steel to high grit stones. He might well just be rounding that apex back and forth as the steel can't support the edge.
I'd actually advise dropping down to 400-500 grit, strop on cardboard and call it good.
Hence useless details. And since no precisions seemed about to come… bulk of the problem could still be adressed. Meanwhile…
Indeed and sorry… fwiw.
thanks for the info
German steels they like to use the DIN designation if they’re going to disclose it and not just sell on the pretentions of « high carbon quality German Stainless Steel » without mentionning it.
« Molybdenum Vanadium » seems more like a low-tier line of such J-knives like Misono, Sakai Takayuki, and whoeverelse.
« Molybdenum Vanadium » seems more like a low-tier line of such J-knives like Misono, Sakai Takayuki, and whoeverelse.
Strop lightly on your 8000 and see if it is more to your liking.
do you suggest stropping with edge leading strokes or edge trailing strokes?
Bobby2shots
Senior Member
Amen to that. Sometimes we just have to come to grips with the fact that some knives may not be worth the time or money to sharpen. TaR knives (Toss and Replace) For those knives, a few sheets of Silicon Carbide wet/dry sandpaper on a flat surface, might be a better solution than buying stones.
Kippington
A small green parrot
500 grit or so.
is 240 okay also ?
i don't have a 500 grit stone
Kippington
A small green parrot
Yeah that will work. Just do it with light pressure.
The idea of the next step (stropping on a much higher grit) is to stabilise (read: deburr and refine) the edge without completely removing the scratches from your 240 grit.
You should end up with micro-serrations that rip through tomato skins with ease.
There are two ways to cut tomato skin effectively. Stupid sharp with the right geometry, which won't last all that long, or teeth. Typically 8000 grit will be too fine, unless you have the right steel, like white 1, and then its when its in really good shape. The state of a tomato also makes a difference. The reason a tomato is hard to cut isn't actually the skin, its the soft flesh behind the skin if you flipped the tomato over and cut the skin against your board, no problem. The softer the tomato, the harder it is going to cut. Incidentally, I find its easier to cut a tomato with a polished knife going across it, rather than wedging it between the knife and the board. I've had plenty of edges that can shave off the top of it standing, but under performed with a straight down cut.
The usual German stuff like Wusthof and Henckels usually run anywhere from 56 to 58 regardless of steel type.
With the right technique you can get them blazing sharp but that would require loads of thinning, sharpening and blood. German knives are just built like a brick sh1thouse and meant to be tough as nails, don’t try to change their nature.
To show off your E-Peen, sure, but for practical use, in my experience up to 3k for these is good, nice bit of bite, sharpness and decent edge retention if you microbevel it properly.
Kippington
A small green parrot
Your knife is too thick behind the edge.
It should do very well with soft foods, but it needs thinning before it performs well in harder foods. It begins to feel like you're splitting wood with a wedge. This is a common problem with mass manufactured knives from many of the big brands, especially after they've been sharpened a bunch of times.
Jovidah
I'll make you a sponsor offer you can't refuse...
For hard stuff IMO it's more about geometry than about the edge itself. If the knife is thin enough you don't even need that much of an edge on a lot of stuff as long as its thin enough. If it's too thick no amount of edge sharpening is going to make much of a difference.
update:
I resharpened the knife with 800 gritstone and the knife is now sharp from bottom to tip it cuts tomatoes well i even repaired the tip it was blunt now its pointy ...
although I see that the edge bevel is a bit bigger on the non dominant side of the knife (the left side)
I resharpened the knife with 800 gritstone and the knife is now sharp from bottom to tip it cuts tomatoes well i even repaired the tip it was blunt now its pointy ...
although I see that the edge bevel is a bit bigger on the non dominant side of the knife (the left side)
when trying to slice an onion in half or a potato after the edge is inside of the veggie 1/3 of the way its very hard to push down i dont understand why ?
Sounds like wedging.
This is why.
I think when I am sharpening using my Worksharp Ken Onion I use mainly 3 belts, 400, 1000, 3000. My Henckels 4star 10-inch which I cut the tomato with I used a 3000 belt any way by what Worksharp says the belts are grit wise. If I don't use the 3000 then I feel the teeth a little more when cutting but it cuts the tomato fine.
I have no issues cutting an onion. It goes right through. Potatoes seem fine also. I get a little noise when I cut carrots but no problem cutting.
My guess is the Henckels 4star knives have good grain structure in their steel for teeth and cutting which they hold. Sharpening wise the Henckels don't match the high levels of sharpness that you guys achieve.
I have no issues cutting an onion. It goes right through. Potatoes seem fine also. I get a little noise when I cut carrots but no problem cutting.
My guess is the Henckels 4star knives have good grain structure in their steel for teeth and cutting which they hold. Sharpening wise the Henckels don't match the high levels of sharpness that you guys achieve.
Last edited:
Woshigeren
Well-Known Member
Also a rather large jump going from 800 and adding a zero 
Sometimes it is best to keep the next progression within a few thousand or even hundred, otherwise you are likely just polishing the bevel to look shinier
Sometimes it is best to keep the next progression within a few thousand or even hundred, otherwise you are likely just polishing the bevel to look shinier
I have 2 questions
1. i think I have never really felt a burr/ it was there but I just couldn't feel it or I felt something but i don't know if its a burr ..... you get the gist of what I'm trying to say
2. how do you know if the knife is fully apexed ?
1. i think I have never really felt a burr/ it was there but I just couldn't feel it or I felt something but i don't know if its a burr ..... you get the gist of what I'm trying to say
2. how do you know if the knife is fully apexed ?
- Joined
- May 3, 2011
- Messages
- 9,812
- Reaction score
- 4,532
Try with a knife you don't care much about. Sharpen one side only, with a coarse stone. At some moment you will feel with your nail an irregularity appearing on the other side. That's a burr.
With knives I don't know, haven't sharpened before, I check using a permanent marker and a 10x-loupe. So I'm sure not to overlook a microbevel. It happens you only accumulate debris on top of the old edge, without having reached the very edge and created a new apex, and only remained slightly behind it. Hard to see with a naked eye.
With knives I don't know, haven't sharpened before, I check using a permanent marker and a 10x-loupe. So I'm sure not to overlook a microbevel. It happens you only accumulate debris on top of the old edge, without having reached the very edge and created a new apex, and only remained slightly behind it. Hard to see with a naked eye.
I'm never able to feel it
You need to try again, then. Find a knife you don’t care about, sharpen with pressure at an angle higher than the bevel angle on a coarse stone, until you do feel it. When you make a big burr it’s unmistakeable.
