Filet knife help

dbalfa

dbalfa

Joined
Jun 23, 2008
Messages
67
I've got a call to build a filet knife. While I have used many of them, I've never made one. I know flexibility is a key but also edge retention. We used to have a saying around my gang, "that knife is sharp but it ain't 'fish cleaning' sharp!"

1. What is the best steel for this application? I was leaning to 440C or maybe ATS-34.
2.What is the best thickness?
3. Depending of stock chosen, what directions should I give to the H-treaters to achieve flex, toughness, edge retention?

Please feel free to post any pictures of filets you've made and discuss the design plus/minus's. I'm sure there are different tip designs that are better than others. Input from folks that have used them to clean fish would be greatly appreciated too.:D
 
I make about 50-75 fillet knives a year.
Most are CPM-154 (similar to ATS-34), .060 to .100 thick.
Just tell the heat treater that it will be a fillet knife, and they will do the rest. Cryo is a good idea. Rc 60-61 works well.
Many just proflle such thin knives and grind the bevels after HT. It takes some skill to avoid overheating the edge, but it is not as risky as with carbon steel. Sharp belts, fast grinding sweeps, and frequent dunks in the slack tub.
Stacy
 
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I use CPM154 for the couple fillet blades I made. I wanted my fillet blades real flexible so I started with .093 stock and tapered the spine down to .060 over the first two inches from the ricasso towards the tip. That keeps the flex down through the handle.
 
bladsmth said:
I make about 50-75 fillet knives a year.
Most are CPM-154 (similar to ATS-34), .060 to .100 thick.
Just tell the heat treater that it will be a fillet knife, and they will do the rest. Cryo is a good idea. Rc 60-61 works well.
Many just proflle such thin knives and grind the bevels after HT. It takes some skill to avoid overheating the edge, but it is not as risky as with carbon steel. Sharp belts, fast grinding sweeps, and frequent dunks in the slack tub.
Stacy
Click to expand...

I would think that the blade wouldn't be very flexible at such a high hardness. Don't you want something closer to a spring temper?
 
Flexibility in a blade is a function of thickness more than hardness. A spring is very hard, but has a high toughness (resistance to breakage).
A full distal taper to the blade, flat grind bevels, and 1/2 to 3/4 wide blade will flex a lot at .060". At Rc60-61 with cryo and proper tempering, the blade will flex nicely. Fillet knives are all about edge retention. They have thin and delicate edges, and must be fairly hard to hold up to wear. I have made 16" fillet knives (10" blade), for tuna, from .125 CPM-M4, and hardened them to Rc 63-64. Scalpel sharp, and very tough. Not much flex, but flex is not needed for a tuna knife.
Stacy
 
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