A few filet knife questions

[rjfm1972]

I am going to make a filet knife for my friends father in law as a thank you gift. I have a scrap piece of cpm s30v left over from some other blades I am working on thats just big enough for a filet knife. My questions are 1) Will S30V make a good filet knife? and 2) What is the ideal thickness for a filet knife? I know they need to be thin, so realistically, how thin can I make a blade with steel of this quality? Thanks for any help!

 

[Doubletrouble]

Being in the Pacific Northwest we use fillet knives almost daily. The best Fillet Knives are very thin my favorite is .030 at the tip and .043 at the handle. It needs to flex well to get all that meat away from the skin and bones. Your steel choice is a good one although it may be a little stiffer than I would like even at a very thin edge. Good Luck!

 

[Stacy E. Apelt - Bladesmith]

CPM-S30v is an excellent choice for a fillet blade. I almost exclusively use CPM-S35VN, which is quite similar.

Flex is about geometry, and thinness controls that the most.
On a 8-10" fillet blade, I use .060" stock and grind from there. The tips are about .030 1" back from the point. I find this a good balance between flex and cutting stability ( stiffness). For smaller blades, or if you like more flex, go even thinner. 1" blade width is plenty for anything but a tuna sword, 3/4" for smaller fillet knives.


THIS IS IMPORTANT:
1) Do all the sanding up to 400 grit, and get everything done before HT. These type steels get hard and tough, and hand sanding after HT should be minimal. Scratches left behind are all but permanent! A satin or sanded finish is best.

2) Get top quality HT and you will have a good fillet knife. Tell them you want the max practical hardness, and that the knife will be used for fillet. The target should be Rc61.
I let Peter's pick the parameters ( I have my blades done in bulk), but 1950F austenitization, followed by cryo, and 400F temper works well when I do my own HT.

 

[Tait]

I second the S35VN as a good fillet knife choice.

I had some trouble with warping with paring knives made from .060 s35vn, and have switched to grinding everything after heat treatment. It takes a lot of ceramic belts o grind but does come out nicely.

Stacy, any trouble with warping or waves?

 

[Stacy E. Apelt - Bladesmith]

I second the S35VN as a good fillet knife choice.

I had some trouble with warping with paring knives made from .060 s35vn, and have switched to grinding everything after heat treatment. It takes a lot of ceramic belts to grind but does come out nicely.

Stacy, any trouble with warping or waves?

One big plus for Peters is they straighten and hardness test every blade. I haven't had one that was bad yet.


I do it both ways. The smaller blades I grind post HT, and as you say, it takes a good grinder and good belts.....and good skills. When doing large batches, it is a time and effort saver, though.
The main advantage for post HT is you only have to do it once. The main negative is that you have to watch the heat. If a basic 120 grit belt finish is what you want, this is a good option.

I have considered making an aluminum grinding block to hold the blades and absorb the heat. I use a wooden block most of the time.

 

[fast14riot]

Stacy, I ue an aluminum grinding block for smaller/thinner blades and it works well. I use 1/4" 6061 angle and clamp my blade to it. I put a layer of clean painters tape on the surface I clamp to to keep the scratches down from any grit or dirt stuck on there, also it gives traction to the blade better than the bare Al does.


-X

 

[rjfm1972]

Thanks everyone for your input. I feel much more comfortable with the steel choice now. This will be a fun project for me.