Filet knife question

H

HelloKombo

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Jan 30, 2015
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Fillet knife question. Hey. You seem like a knowledgable guy when it comes to knives. I sell a fishing gadget that is an all in one fish club with a fillet knife hidden inside. When we really pressure the blade by flexing it, it bends. We were told this is normal by the guys at house of knives? We have had a large retailer reject our knife because he said it shouldn't bend when flexed. I have asked numerous people but I can't seem to figure this issue out. I need some advice on what steel to use for our product if you wouldn't mind assisting me. Here is some info to better help understand what we're doing

Currently we have a 3CR13 stainless steel. It is 420. Our product is made in china and we were told this is the best steel for the price point. We don't have the margins to use US or German steel. Our customers love the blade we have now so we would like to continue using it, but if the big retailers want a steel blade that doesn't bend, only flexes, we have to accommodate them. Can you give me your advice on this? The competitors are using 420HC and I assume theirs don't bend. Maybe it's the shape of our blade? Or does it need that black coating to make it more rigid? Any help is much appreciated.


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Anyone on that can give me advice on what stainless steel to use in my fishing fillet knife? The steel we currently use is 420 an it is bending??
 
I consolidated your posts here. They were hidden in other threads on different topics.
 
HelloKombo said:
Anyone on that can give me advice on what stainless steel to use in my fishing fillet knife? The steel we currently use is 420 an it is bending??
Click to expand...

420 steel is a low carbon stainless steel and is not suitable for a quality knife.

It only has .15 carbon (as a minimum) which will not allow it to harden sufficiently for use as a knife. Because of the low carbon content it will bend under stress rather than flex.

You should look in to other steels rather than using this cheap Chinese steel.
 
Several things here:

1) Most important is that this site does not allow discussion of sales or sales related threads by registered and basic members. I'll let it slide for now because we are discussing flex and steel choice. Please keep all mention of selling and pitching your product to retailers out of here or your thread will be closed.

2) Flex is a factor of thickness and blade bevel grind. Steel type and hardness makes little or no difference. To decrease flex, make the blade and spine thicker. Most of my customers like some flex in a fillet knife, but the folks who fish for large fish like their knives longer and stiffer. I jokingly call these big stiff fillet knives "Tuna Swords".
In a normal size fillet knife, .060" blades will flex, .125" won't....pretty simple.

3) Steel choice for a simple fillet knife can be as simple as 440C. This is a low cost stainless steel that takes a good edge, and easily heat treats. 420 is not a blade steel at all and would be rejected by any knowledgeable knife person. I believe you have been badly misled by someone in China about it. It also shows that you have no knifemaking knowledge or you would have rejected it yourself. It would do you good to do some studying and research before you spend more money on any more prototypes.





To those who wish to post answers - You are also supposed to keep sales talk out of this thread, so don't put any suggestions about sales in your posts either.
 
Stacy, just wish to say "my compliments" to your decision to allow thread. The OP wasn't really trying to talk about "sales", but seeking advice on steel, shape, etc. I think his purpose of mentioning the product was to give background to help in discussion of steel type and flex question.

Nothing really for anyone to add about steel and shape - you've covered it quite well. 430HC steel was used by Kershaw in making a cheap version of the 1670 Blur just for Amazon to sell. I got one, and like the knife quite well, while the blade would sharpen to shaving level it just didn't hold an edge as well as I felt it should. I made another blade using 14C28N and it's a LOTS better.

Ken H>
 
Fillet knife steel is more governed by the amount of distal taper ground into a blade.
We could make fillet knives flex much more with a softer "spring" temper" that is just
not the way quality fillet knives are made. If we are talking a high 40's to low 50's for
a very flexible blade and high 50's to low 60's for a quality blade thats huge. So keep
the Rc up and do a good distal taper and the blade will flex.
Ken.
 
Stacy E. Apelt - Bladesmith said:
Actually Ken, Unless I understand Young's modulus of elasticity, temper and hardness are not an issue in flex. Flex is a mater of thickness. Temper and hardness are the factors that determine where flex turns to bend or to break.

Here is an old discussion of the subject:
http://www.bladeforums.com/forums/showthread.php/530366-Rehashing-quot-flex-quot
Click to expand...

This is my understanding of YMoE as well. Thickness determines flex, hardness determines whether a set is taken or the blade breaks once the MoE is exceeded.
 
I agree with the 440C recommendation, as long as it really is 440C
You cannot trust and must verify in this instance, and at every step in the process and every order.


420HC and 420 are not blade steels,
Yes Buck uses 420hc, that's because it's cheap not because ti's good

There's a long discussion here about 420hc being crap.
 
Stacy's steel discussion is right on the money. All I have to add: "Bend" and "Flex" are two very different terms in the knife world. Flex is springiness. If you press sideways against the tip of the blade, does it move? Does it spring back to its original straightness? I like a fair bit of flex in my fillet knives since I tend to work with smaller fish (under 20 lbs).

Bend is damage. If you press sideways against the tip and it bends but does not spring back, that is very bad. Knives will be returned by the truckload if they do that.

Just clarification.
 
Stacy E. Apelt - Bladesmith said:
Flex is a mater of thickness. Temper and hardness are the factors that determine where flex turns to bend or to break
Click to expand...

+1

Very thin knife:
2mDsHZB.jpg


Fillet knife (also thin of course)
3Leq5rI.jpg


They return to perfect flat after the bend


Pablo
 
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