Mystery stainless sharpening nightmare

S

Smiling

Joined
Nov 21, 2019
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1,495
So, a guy from work has asked me to sharpen a knife for him since he is inexperienced and lacks equipment for that too.

It is:
Fox Outdoors throwing knife.
Double edged blade with uneven grind (line in the middle is not straight on either side), tang is also a handle and has lots of holes on it...

The box says only 2 things:
Stainless steel
Made in China

The knife came very dull, and it still is very dull.

So, it is extremley frustrating. My Cold Steel knives in SK-5 and 52100 get shaving sharp in matter of minutes.
No matter what stone I use and how light or hard I press it just doesn't show any improvements.

Any ideas what should do it, or I should just return it to him as dull as it was?
 
As a 'throwing knife' by design, I'd bet it's not heat-treated to be very hard, if it's hardened at all. Such knives are made to avoid breakage (for toughness), rather than for holding a fine, sharp edge (which requires hardening & tempering, via heat treat). They don't need to be very sharp in the true sense, but just enough to penetrate whatever they're thrown at (like cork targets or end-grain wood for same). The tips & edges will dent or deform easily, but likely won't break, even under severe use/abuse. But any fine edge put on it, if that's possible, would be too soft & frail to hold up.
 
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Stainless Chinese throwing knife? It might not even be hardened. Does it scratch easily with a common utility knife blade?
 
There's a term for these types of things. XXXXX-Shaped Object. In your case it would be Knife-Shaped Object. This term is given to those things which resemble the first word in the string but are basically junk. Probably what you've got there. If it's not very hard you may have some better success if you increase the included angle to a level that makes the edge stronger and more supported. That will GET it sharp, but won't KEEP it sharp.
 
Mr.Wizard said:
Stainless Chinese throwing knife? It might not even be hardened. Does it scratch easily with a common utility knife blade?
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Well, even dull point of my boxcutter schratched it easily... this thing as you guys said - probably isn't even hardened.

I'll most likley give up and tell him that what he got is unfortunatley a piece of junk.
Probably good for practice... but that's about it.
 
Perhaps if you tell him that the metal is too soft to be sharpened properly instead of saying it's junk. Let him make that determination. Sometimes better to keep the harmony at work. Only suggesting this because it has happened to me numerous times with co-workers. I usually end up giving them a quality knife in exchange for theirs.
 
It's important to consider the purpose of the device you have been asked to sharpen.

What would you say if a coworker handed you brick and asked you to sharpen it? "That's not a knife. You can't really cut anything with that. It's not designed for cutting. That's a brick."

A throwing knife is not designed to cut anything. It's a nice step up from a brick. But it's not a cutting tool. It's a throwing device kind of like a dart. As others have said, it's metal and treatment are designed for impact.

Said another way, if you hardened a throwing knife sufficiently to take a nice edge, it wouldn't be very good for throwing any more. Because this new hardened knife would probably break off it's point after 20 or 30 or 50 throws.

This tool has a purpose and that purpose is not cutting. So it's not really useful to sharpen it. It's not necessarily bad quality or "junk". Just not designed for real knife use.

Brian.
 
bgentry said:
Said another way, if you hardened a throwing knife sufficiently to take a nice edge, it wouldn't be very good for throwing any more. Because this new hardened knife would probably break off it's point after 20 or 30 or 50 throws.
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I'm not a thrower so I cannot claim direct experience but to the best of my knowledge there are carbon steel throwing knives with a spring temper that appear to handle regular use just fine. Obviously the tip geometry is specialized but I don't think throwing knives have to be innately tougher than swords, for example.
 
I'll return him the blade today at work.

I'll tell him that since it is a stainless steel throwing knife, the steel is made very soft to be more impact resistance, therefore it can't take a good edge because of how soft it is.

I somehow managed to make it sharp enough to cut paper, it is still not shaving sharp though, but it is better than it originally was, so I at least did something.
 
Smiling said:
No matter what stone I use and how light or hard I press it just doesn't show any improvements.
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Hi
So what coarse stone are you using ? Got any regular bricks?

Smiling said:
I'll return him the blade today at work.

I'll tell him that since it is a stainless steel throwing knife, the steel is made very soft to be more impact resistance, therefore it can't take a good edge because of how soft it is.

I somehow managed to make it sharp enough to cut paper, it is still not shaving sharp though, but it is better than it originally was, so I at least did something.
Click to expand...
Hi
Have you raised a burr?
Try a 30 or 40 degree per side micro bevel.
There's a few videos on youtube of "pro" sharpeners who cant sharpen one dollar knifes... And a few of regular guys sharpening shovels and butter knives... It can be done
 
Throwing knives dont need a sharp edge just a sharp point and all my throwers are hardened 40-54 Hrc. I brake tips occasionally and reshape after a multiple sessions. But if a thrower has a sharp edge I usually dull it.
 
I will typically dull the edge when I buy a new throwing knife. If I make a set I will purposely leave the edge thicker than a normal knife with a robust tip as well.
 
3fifty7 said:
I will typically dull the edge when I buy a new throwing knife. If I make a set I will purposely leave the edge thicker than a normal knife with a robust tip as well.
Click to expand...

I prefer them like that because at times I put my finger on the edge using different techniques.
 
bucketstove said:
Hi
So what coarse stone are you using ? Got any regular bricks?


Hi
Have you raised a burr?
Try a 30 or 40 degree per side micro bevel.
There's a few videos on youtube of "pro" sharpeners who cant sharpen one dollar knifes... And a few of regular guys sharpening shovels and butter knives... It can be done
Click to expand...
I did manage to do something with #600 stone and high angle... burr was a problem and I had to break it off.

It got sharp enough to cut newspaper, but it won't shave.

Those things never happehed to me with my carbon steel knives. I only ever encounter burr on kitchen knives. But never so extreme.

I gave him the knife back and I told him the steel is too soft. He understands fortunatley.
 
Some really cheap stainless steel knives can be hard to sharpen

Maybe its the amount of material that needs to be removed or something in there (high chrome?) that gives it a not so fine grain structure

But it seems like they hold toothy edges, but not fine push cutting edges well

This includes my 80s cheap chinese kitchen knives
 
He has told me that he plans to use that blade kinda like a wallhanger - just keep it on his desk as a decoration, he wanted it to be sharp for any case of emergency like a burglar for example LOL.

Anyways I'm glad that this is the case since that knife really isn't for anything else.
 
Update:
He decided to try to throw it for fun and it got ruined pretty fast...
Apparently after 10-20 throws he lost his tip and bent the entire knife while pulling it out from wood.
 
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