Filleting Edge geometry

D

Dillon.s

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Mar 29, 2017
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Good day all I hope all are doing fine amid the current circumstance.

I am looking for some help as I have currently started making some filleting knives with all the extra time I have on my hands and just wondering:

- how thin should I grind down to the edge before sharpening?
- what angle should I be sharpening at?
- and what grit should I work up to when sharpening

I am working with 440c/s35vn it that matters at all

any tips and insights would be much appreciated

thanks
 
440c I would take down to about .008-010 before sharping about about 20 degrees per side at 220 grit before buffing. Not exactly the right steel for a good flexible fillet with a thin thin edge. Carbides are on the bigger side. It’ll work better than most any other fillet knife you can buy at a store still.


S35vn on the other hand I’d take down to a zero edge and sharpen at 15dps with as high a grit as you have. I’ve never worked with it due to the number of blades I have from my last aeb-l batch (thanks jt), but it is close to being at the top of my list for my next batch. I think only s45vn is ahead of it for me.
 
Awesome thanks for your insight is there any specific thickness I should get the spine ground to or is it just preference on how flexible you want the knife to be?
 
I make a lot of fillet knives. 440C will work, but you have to keep the edge a bit thicker as Tag pointed out. AEB-L works well, but the edge needs touching up after each use ( not really a problem).

I use CP-S35VN almost exclusively for fillet knives. The edge is very long lasting and I take the blades to Rc62.

Get it in .060 thickness, profile the blade only, and do HT.
After HT grind in the bevels to a zero edge and leave the finish at 400 grit.
Sharpen with 120 grit at anywhere between 10° and 15° per side.
Lightly strop the edge on a charged leather strop.
Buffing the edge on a fillet knife is very dangerous and not advised. Strop the edge on a very fine stone or a leather strop charged with green chrome.

The 120 grit edge will cut very aggressively. A finer grit edge may actually feel less sharp. If you want to try 220 grit, that is about as fine as I feel you should go on a fillet blade.
 
Stacy E. Apelt - Bladesmith said:
I use CP-S35VN almost exclusively for fillet knives. The edge is very long lasting and I take the blades to Rc62.
Get it in .060 thickness, profile the blade only, and do HT.
Click to expand...
Stacy - turns out that my sister wants a filet knife .... so this thread caught my eye. Question - where are you finding cpm-s35vn in 0.-6" thickness? the thinnest I am finding it is about 0.09" ??

(I am actually surprised you mention that AEB-L needs touching up after use? I thought AEBL is supposed to be quite quite tough and with good edge retention. Or ... is there something different about this application that dulls it?)
 
If I may,

AEB-L is the finest grained ingot stainless steel I have ever heard of. I have found it is incredibly tough, but its wear resistance is relatively low. This fact is offset by its toughness and edge stability, which means that it can be ground very, very thin, and hold up to uses that might damage another stainless steel at the same geometry. Because of its lower wear resistance, initial sharpness tends to go relatively quickly, but it requires little more than stropping or honing to gain it back.
 
David Mary said:
If I may,

AEB-L is the finest grained ingot stainless steel I have ever heard of. I have found it is incredibly tough, but its wear resistance is relatively low. This fact is offset by its toughness and edge stability, which means that it can be ground very, very thin, and hold up to uses that might damage another stainless steel at the same geometry. Because of its lower wear resistance, initial sharpness tends to go relatively quickly, but it requires little more than stropping or honing to gain it back.
Click to expand...
Thanks, I think I’ve got that. It still leaves me a little confused though, why it is so hard to grind aebl below about 0.01 . When I do that, I start getting tear outs (which I assumed was the result of either large carbides, or large grains). Not so I guess? (But maybe that is too off topic..)

so, it sounds like the trade off is pretty subtle ... like, aebl dulls more quickly, but can easily be brought back to a good edge, whereas s35vn is harder to bring back to a good edge, but keeps that good edge longer. Does aebl win in terms of corrosion resistance? This has me wondering about the beliefs I have had for steels for applications from hunting, to fillet (the subject here), to somewhat abused kitchen knives......

so many alloys, so little time ... :-)
 
Cushing H. said:
a little confused though, why it is so hard to grind aebl below about 0.01 . When I do that, I start getting tear outs (which I assumed was the result of either large carbides, or large grains). Not so I guess?
Click to expand...

Check out Larrin's comparison pics between 440C and AEB-L:

440 C
440C-HT.jpg


AEB-L aka 13C26
13C26-HT.jpg


So this makes me wonder what is going on with your AEB-L because that doesn't sound like expected performance from it if heat treated properly. I have been able to grind mine paper thin without tear outs.

aebl dulls more quickly, but can easily be brought back to a good edge, whereas s35vn is harder to bring back to a good edge, but keeps that good edge longer.
Click to expand...

That's about how it seems to me. But also, AEB-L can be ground thinner than S35VN can without becoming brittle, so it will keep cutting on geometry alone a long time after it has lost the bite of initial sharpness. Longer than a dull S35VN (or any other steel) blade of thicker geometry. Of course those cuts won't be as clean as cuts with a freshly sharpened edge.

Does aebl win in terms of corrosion resistance?
Click to expand...

I've never had corrosion issues with AEB-L, but I also don't have a ton of experience with it, and certainly not enough to compare it to S35VN, which I have even less experience with.
 
Cushing H. said:
Thanks, I think I’ve got that. It still leaves me a little confused though, why it is so hard to grind aebl below about 0.01 . When I do that, I start getting tear outs (which I assumed was the result of either large carbides, or large grains). Not so I guess? (But maybe that is too off topic..)
:)
Click to expand...
0.01 is 0.254mm and that is more then thick ......you don something wrong
 
Yes, you are creating a burr of rough metal. After grinding the edge down on the belt grinder, work it on a fine stone and strop it, and AEB-L will be insanely sharp.

My comment about needing touching up more often was well explained by David.

Cushing - The .070" S35VN makes a good fillet blade. Once the distal taper is added it is plenty thin enough. If you needed it thinner, you could ask Aldo (or someone else) to run it through the surface grinder a couple more times. I buy .070" S35VN for fillet knives.. The .100" is also very good thickness for larger kitchen blades. I make most all my cutlery blades from S35VN in those thicknesses. I buy a sheet or two of the steel (7X36") when I order.
 
Stacy E. Apelt - Bladesmith said:
Yes, you are creating a burr of rough metal.....
Cushing - The .070" S35VN makes a good fillet blade. Once the distal taper is added it is plenty thin enough. If you needed it thinner, you could ask Aldo (or someone else) to run it through the surface grinder a couple more times. I buy .070" S35VN for fillet knives.. The .100" is also very good thickness for larger kitchen blades. I make most all my cutlery blades from S35VN in those thicknesses. I buy a sheet or two of the steel (7X36") when I order.
Click to expand...
Hmmm... I could have sworn those were pullouts ... but ... I have a couple blanks of aebl left, so will try again to get thinner. If I see the same thing I will post photos (not sure when I will be able to do that though)

stacy - are you able to share with me (pm?) where you find S35VN in 0.07”? I just am not seeing it below 0.09” ...
 
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