question about a sharp knife that cant cut tomatoes well

[Nemo]

As Jovidah said, Western Stainless is generally much coarser-grained than decent Japanese stainless, even the cheap stuff like AUS8.

No point going beyond 1k with Western Stainless in most cases.

AUS8 will usually take a 3-4k edge nicely.

In addition to the sharpening resources mentioned above, its worth checking out the knifeplanet sharpening school videos.

 

[r0bz]

knifeplanet sharpening school

I already watched peter

 

[ian]

Simple answer is that it isn’t as sharp as you think it is.
Super polish done well will fall through tomato skins. Look at a couple of Salty’s videos (the OG of the tomato slice vid)



Just leave it at 800grit if it’s working well off that stone.

Does it say that's a high grit edge somewhere?

This is a bit unrelated, and idk if I'm just not good enough, but my high grit edges have worse tomato-skin-tested-edge-retention than my low grit edges. (They both cut them ok right off the stones, but the low grit ones stay capable much longer.)

I do second the question 'what exactly are you sharpening'. If it's German stainless then you're mostly wasting your time. Even if you can create a perfectly polished super fine edge 8000 grit edge it just won't hold it.

(and to @Nemo's posts)

And,,,,,,,, get yourself a 2k, or 3k or 4k stone. 800 to 8k is too big a jump.

@M1k3, great god of SG 500 -> 10k progressions, I summon you!

 

[M1k3]

Does it say that's a high grit edge somewhere?

This is a bit unrelated, and idk if I'm just not good enough, but my high grit edges have worse tomato-skin-tested-edge-retention than my low grit edges. (They both cut them ok right off the stones, but the low grit ones stay capable much longer.)



(and to @Nemo's posts)



@M1k3, great god of SG 500 -> 10k progressions, I summon you!

No, no, no. SP 120 > 10k.

Honestly, I'd stop on the 800 stone. Not even touch the 8k for cutting tomatoes.

 

[Kippington]

Sharpening on coarse stones with light pressure, then stropped on a waaaayyyy finer grit - that's a tomato killing edge.

 

[dough]

Just a thought but why test an edge on paper if plan to cut tomato. Just test your edge on tomato.

 

[ian]

Just a thought but why test an edge on paper if plan to cut tomato. Just test your edge on tomato.

Because it rules out a bunch of other reasons why it might not be cutting the tomato?

 

[ModRQC]

Because you'd have to clean the whole blade carefully making sure not to contaminate and have something to do with those tomatoes in the next 30 minutes or so? Or garbage it for no good reason...

There's a difference between testing an edge and testing an edge. Cutting three different kind of papers for 30 minutes is obviously a waste of time and not understanding the paper test right. But when you use thin paper from a consistent provenance, you just wipe and dry the blade and get to know within 10 seconds if there's burr remnant, if the edge is true on the full length, and from the sound how well it will cut what kind of stuff exactly.

 

[branwell]

Just a thought but why test an edge on paper if plan to cut tomato. Just test your edge on tomato.

Testing on what you want to cut is a great way of seeing if you've optimized the edge for that task, but the old paper cut test has its place too I think. Its a very simple test requiring virtually no skill to see if you have a clean consistent edge from heal to tip.

 

[Bobby2shots]

it feels the same

And what do you mean by "same"??? Same as in "no bite" in both directions? Plenty of bite in both directions?

Paper cutting tests are often useless unless you know specifically how to interpret what's happening. Any reasonably sharp blade can cut paper,,,, it's how smooooothly the cut feels and sounds as you draw the entire edge of the blade through the cut that tells you precisely where along the blade edge you might need more work.

When you worked on your 800 grit stone, did you try marking the edge (apex) with a sharpie to see if you were using the correct angle and actually hitting the apex?

 

[r0bz]

And what do you mean by "same"??? Same as in "no bite" in both directions? Plenty of bite in both directions?

Paper cutting tests are often useless unless you know specifically how to interpret what's happening. Any reasonably sharp blade can cut paper,,,, it's how smooooothly the cut feels and sounds as you draw the entire edge of the blade through the cut that tells you precisely where along the blade edge you might need more work.

When you worked on your 800 grit stone, did you try marking the edge (apex) with a sharpie to see if you were using the correct angle?

plenty of bite in both directions, I did not do the sharpie method, the cut of paper feels smooth about the sound i don't know how to describe it.

I raised a burr on one side of the knife then raised it on the other side (did the same strokes on each side) then I deburred by stropping on the low grit stone and then went to stop on the high gritstone.

 

[r0bz]

plenty of bite both sides

Sharpening on coarse stones with light pressure, then stropped on a waaaayyyy finer grit - that's a tomato killing edge.

what grit do you consider coarse?

 

[Bobby2shots]

plenty of bite in both directions, I did not do the sharpie method, the cut of paper feels smooth about the sound i don't know how to describe it.

I raised a burr on one side of the knife then raised it on the other side (did the same strokes on each side) then I deburred by stropping on the low grit stone and then went to stop on the high gritstone.

and,,,What about Nemo's question which you haven't answered yet,,,,,, what knife is it?

 

[r0bz]

and,,,What about Nemo's question which you haven't answered yet,,,,,, what knife is it?

I'm not sure of the brand
i know it's not an expensive knife
it is written on it: MOLYBDENUM VANADIUM STAINLESS STEEL
I thought its german steel earlier... sorry for my confusion

 

[ModRQC]

Lol the question of what steel/make was answered like three times.

These kind of thread are so funny. No one reads, everybody answers.

 

[ModRQC]

OP: there's a difference between stropping on your 8K as you said at some point, and "spending a lot of time" like you mentioned earlier on.

800: deburr until you get the killer edge. Wash and try your tomato.

8000: light stropping, few strokes per side, no weight. Will clean without removing the bite. Wash and try your tomato.

8000: full motion. You know you've really polished that edge when it starts to "grab" at the stone. Or burr feeling method. Wash and try your tomato.

That should give you plenty of thinking stuff to find your ways.

If you have a coarser stone, you can try it also. Full jump or stopping at your 800 first.

If you have a med stone, you should definitely try it for a good all-around edge that bites into tomato.

 

[r0bz]

OP: there's a difference between stropping on your 8K as you said at some point, and "spending a lot of time" like you mentioned earlier on.

800: deburr until you get the killer edge. Wash and try your tomato.

8000: light stropping, few strokes per side, no weight. Will clean without removing the bite. Wash and try your tomato.

8000: full motion. You know you've really polished that edge when it starts to "grab" at the stone. Or burr feeling method. Wash and try your tomato.

That should give you plenty of thinking stuff to find your ways.

If you have a coarser stone, you can try it also. Full jump or stopping at your 800 first.

If you have a med stone, you should definitely try it for a good all-around edge that bites into tomato.

what is a med stone ?, i have a 120 grit stone, and a double sided 800 and 8000 stone

 

[ModRQC]

Your 800 is about one but while it will provide plenty of bite you can work out a good edge out of a 2K stone for these kind of steels. Feeling will be quite finer, plenty of bite and aggressivity still.

Edit: @r0bz I'm not saying go buy one. Do my test first. Chances are you can work something out with 800 - light 8000 stropping that's about the same as 2K but possibly more durable.

Your 120 is ideal to give the primary edge when that kind of steel is very fatigued. Perhaps this is something you didn't think about neither. If the steel of your knife is very fatigued, you can sharpen it on 800, but you won't have removed the fatigued steel. All kinds of failure from cutting paper to cutting stuff could follow. Or not... So while you're at testing, you can always visit your 120 first.

 

[r0bz]

Your 800 is about one but while it will provide plenty of bite you can work out a good edge out of a 2K stone for these kind of steels. Feeling will be quite finer, plenty of bite and aggressivity still.

Edit: @r0bz I'm not saying go buy one. Do my test first. Chances are you can work something out with 800 - light 8000 stropping that's about the same as 2K but possibly more durable.

Your 120 is ideal to give the primary edge when that kind of steel is very fatigued. Perhaps this is something you didn't think about neither. If the steel of your knife is very fatigued, you can sharpen it on 800, but you won't have removed the fatigued steel. All kinds of failure from cutting paper to cutting stuff could follow. Or not... So while you're at testing, you can always visit your 120 first.

would you suggest deburring by stropping on the 800 stone or doing the push and pull method with very light pressure?

 

[Bobby2shots]

Lol the question of what steel/make was answered like three times.

These kind of thread are so funny. No one reads, everybody answers.

Obviously you haven't read it either.

 

[tostadas]

Just a thought but why test an edge on paper if plan to cut tomato. Just test your edge on tomato.

Paper is a quick way to check for missed spots. It can be obvious if theres one location that catches on the paper when testing.

would you suggest deburring by stropping on the 800 stone or doing the push and pull method with very light pressure?

I'd recommend checking out @Kippington method of deburring with a very high angle. I find this method very effective to ensure you remove the burr.


for reference;
https://www.kitchenknifeforums.com/threads/kippington-deburring-video.44003/

 

[ModRQC]

Obviously you haven't read it either.

its 58 Rockwell the hardness

it's German stainless

And then he retracted the German aspect. Which leaves make to be determined indeed. But really 58HRC stainless is all we needed to know from the start.

 

[ModRQC]

would you suggest deburring by stropping on the 800 stone or doing the push and pull method with very light pressure?

You mean, if you start anew with the 120 first? Yes, I would just use the 120 for the primary edge, and since I am a conservative guy, I'd just do what you did so far with the 800 afterwards, although it won't need as much work with the primary already set. You can sure try jumping to 8000. Sky is the limit, trying the only way to explore.

 

[r0bz]

And then he retracted the German aspect. Which leaves make to be determined indeed. But really 58HRC stainless is all we needed to know from the start.

well i was wrong i guess, we all make mistakes sometimes

 

[Bobby2shots]

And then he retracted the German aspect. Which leaves make to be determined indeed. But really 58HRC stainless is all we needed to know from the start.

So where do you see 58 Rockwell being confirmed??? So far w'eve had "it's 58 Rockwell",,,, then "it's German steel",,,, now we have "It's not German", etc. What "kind" of knife??? a carver???? a bread knife???? A cleaver??? A paring knife???? Try reading before ridiculing others who are genuinely interested in helping this individual get the results he's looking for.

 

[Jovidah]

Technically speaking one doesn't rule out the other... molybdenum vanadium steel can be used for all sorts of things, both the German X50CrMov15 / 1.4116 or the Japanese AUS-8. It's a somewhat generic term, but sadly sometimes that's all you get from the manufacturer.
If it's a dodgy cheap knife there's also the risk of the heat treat being botched.

 

[ModRQC]

well i was wrong i guess, we all make mistakes sometimes

There's no problem with that.

 

[ModRQC]

So where do you see 58 Rockwell being confirmed??? So far w'eve had "it's 58 Rockwell",,,, then "it's German steel",,,, now we have "It's not German", etc. What "kind" of knife??? a carver???? a bread knife???? A cleaver??? A paring knife???? Try reading before ridiculing others who are genuinely interested in helping this individual get the results he's looking for.

Oh I've read which you clearly didn't. Introducing a new layer of interrogations doesn't make me wrong. I think a serrated knife was out of the question when he mentioned the rod, if it was ever in it. From there, and taking into account the OP seemed reluctant or unable to provide precisions as required, I really don't care. If it's a petty or a slicer, if it's the worse heat treatment or the best, or even if it's 56HRC, or carbon steel for all that matters, the fact is a thrift store knife can be sharpened and should cut tomatoes out of it.

From there, pressing the OP about info for about the sixth time... the answer is more simple than what knife it is or what steel it is. I think "spending a lot of time" on a 8K stone, and needing to ask questions here about results, means the edge doesn't bite the tomato, which is not entirely surprising. For an edge so fine to fall through, it would take skills... and even there. I was assuming those where in some proportion lacking - or he just wouldn't ask.

I'm guilty of all charges about ridiculing you if it helps you sleep tonight. But I've read and saw through useless details before replying.

 

[Bobby2shots]

I'm guilty of all charges

" I've read and saw through useless details before replying".

Yet you said "that's been answered three times" and "others don't read".

It's those "useless detail" questions that have gotten us from "It's German steel",,,,, to now it's not.

It's 58 HRC,,,,, to possibly "now it's not"????.

 

[ian]

Sigh….

In other news, did you try sharpening it again yet, @r0bz? I’d read through the thread, but it’s too much work to sift through the discussion about who has read the thread.