New project, a fillet knife

Lerch

Well-Known Member
Hi all

Well a buddy of mine approached me today with a knife he wants me to build for him, a fish fillet knife. After some thinking this is what i am coming up with

Blade 7" long, 4" handle, 11" OAL
1/16" 440C steel blade
Hollow Ground and slightly curved blade
Heat Treat/plate quench/cryo and temper to apprx RC 57
Red and Black G10 handle with red inner liner

After reading to help prevent warping i was planning on grinding the blank steel to profile, drilling and then heat treating. after this do the blade grinding. I also thought about doing a little file work on the spine roughly 1.5" out onto the blade and follow it back along the handle (if that makes sense to anyone )

Any opinions/ideas? would this width of steel be flexible yet tough enough to be used as a fillet. would it hold a edge or would it need to be harder?

before this a fillet knife had never crossed my mind so any tips or ideas would be great lol

thanks
steve
 
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Remember that steel that thin likes to overheat in the blink of an eye, go slow with the grinding and cool often, maybe every pass...

One thing I've found that really helps when grinding steel this thin/flexible is to make a wooden or micarta piece that conforms to the profile of the blade, and clamp the blade to it while grinding.... it helps to keep the blade from flexing as you grind.

Good luck!
 
I like the idea that you listed here, but i guess im not sure how to make this or what it would look like
 
I'm wondering about the hollow grind. That's an awfully thin blade to take that much steel away from. What do you think of a flat grind from the spine to the edge? By that I mean just the primary bevel all the way to the edge, something like a scandi grind but all the way back to the spine. It would also present a constant wedge with no swell towards the spine that might resist the slice.

Doug
 
I listed a hollow grind because that is the only grind i am familiar with so far, well i did one slack belt grind also but i had a knifemaker standing over my shoulder. I figured a hollow grind would give a little backbone/spine to strengthen it up but I see what you are saying. and maybe a flat grind or beveled edge would allow the knife to slide along the fish and table better when working. Ive ordered one 18" piece of 1/16th 440c today so it should be here probably thurs, i have a couple of others in line first for friends but i am ready to try this one, hope to get two knives out of the one chunk of steel, ya know a back up :)
 
Here is another suggestion for making a knife from thin stock, especially if you want to try making on continuous bevel from spine to edge. Profile the knife, have it heat treated, then grind in the bevels. That means that you will have to watch the heat from grinding real well. To cut the bevels like that, I would start out at about 45 degrees and cut a blunt edge, just a little finer than the usual dime thickness. The idea would then to decrease the angle of attack in stages and slowly work the bevels back to the spine. When you get the bevels back to the spine I would then grind the bevels down to the final edge as you refine the grind. If you don't want to do a single bevel you could refine the grind on the bevels and the apply a secondary bevel at the edge. Remember to go slow and cool your work often.

Doug
 
1/16" thick 440C works fine for a fillet blade. I have made severial fillets, and use a full flat grind, taking the edge down to .005 thick, with a secondary bevel. I have heat treated before grinding the bevels and still have had warpage problems, also have ground the bevels first and had no more trouble than doing the heat treat first, I don't know why, some warp and some don't. I do know that grinding heat treated 440C that thin is a royal pain. 57RC should be good. Hope this helps.
 
Thanks for all the info guys. So i have the metal in house now, i have two projects to complete before i start on this one so it will be a week or so.

I am set on profiling the knife, heat treating and cryo, then doing the grind, but when should i temper? before or after the primary knife grind??

It seems pretty obvious that hollow ground is not the way to go. I have done a slack belt grind before so i may try that.

Mr Miller was kind enough to hook me up with some precision ground 1/16th in a big sheet so i got some to work with if warp becomes a pain.

This is a bit of a odd question but what would you all recommend charging for a knife like this? i really dont have a idea because the material cost is not to large given the steel thickness but the work seems like a pretty good stretch

thanks
steve
 
I like the idea that you listed here, but i guess im not sure how to make this or what it would look like

Sorry I wasn't more clear. Once you have the knife profiled but before you grind in the bevels, trace the shape onto a piece of micarta, wood, or whatever is handy, then cut that out and clamp it to keep the blade from flexing as you grind it. Not so important with bowies and thicker knives, but with fillets and other thin knives it is very useful.

I like a full flat grind on fillets...
 
I am set on profiling the knife, heat treating and cryo, then doing the grind, but when should i temper? before or after the primary knife grind??

Temper right after cryo, no matter what your grinding schedule is. You want to relieve the stress in that hardened steel right away. Grinding before temper is a sure recipe for disaster.

I would shoot for 58-59Rc on 440C, may as well make the most of its edge-holding properties. It sounds like "only a couple points" but the difference between 57 and 59 is actually pretty major. Flexibility comes from thickness compared to length, not hardness.

I also vote for a full flat grind. A hollow grind doesn't do squat for cutting ability on a blade that thin, it only makes it a little weaker.
 
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Thanks for the info. I have never done a flat grind before, should be interesting :) I may try one as a flat grind and one as a slack belt grind. Hollow ground is out, glad i didnt waste my time :)

thanks
steve
 
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