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Aiden CC

Filet Knife Thickness

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A few weeks ago I bought some old hand saw blades (measured at 0.042" thick with my micrometer), and I was wondering if that would bee too thin to make a filet knife out of. The plan would probably be to do a small scandi grind as the stock is already so thin. I've wanted to try making a knife that floats and I figure this would be a good bade type to give that a shot, so I ordered some cork flats to do a stacked handle with. Anyways, do you all think 0.042" would be thick enough for a filet knife or should I look for some thicker stock?

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I too have been eyeballin an old saw fer the same type of blade it looks to be close to the thickness of my old short rappala filetter but, I havent measured it out  yet, ......the list always grows...........:rolleyes:

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I've made a couple of fillet knives from a bandsaw blade of a very similar thickness.  I put a decent bevel on them and buffed them to a shine.  They came out very well in my mind.  I also made a small kitchen knife from the same saw blade and put a full flat grind on it.  Talk about a slicer!  It was by far the sharpest knife that I've made yet.

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Take a look at a good fillet knife, Rapala for instance, mine have a very slight full bevel with a convex edge. 

Some do have a small micro bevel like from a hand held "V" sharpener. 

 

Edited by Vern Wimmer

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Ive made quite a few filet knives lately, i usually shoot for roughly 0.075 inch thickness. Any thinner than that and ive found heat treating to be tricky. Im sure its doable, however. My setup is less than ideal, and my experience much lower than many. 

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1 hour ago, Will W. said:

Ive made quite a few filet knives lately, i usually shoot for roughly 0.075 inch thickness. Any thinner than that and ive found heat treating to be tricky. Im sure its doable, however. My setup is less than ideal, and my experience much lower than many. 

I like that thickness for kitchen knives, I've gone down to around 0.055" for my thinnest paring knife. I'm currently back at my college, which means I don't have any good grinders or general knife making equipment, however I do have the advantage of a materials science lab with a director who likes to help students with passion projects. The saw blade ought to be heat treated already,  I can test the hardness at some point and see exactly what it is, if needed, I could use a proper kiln to re-harden it.

4 hours ago, Vern Wimmer said:

Take a look at a good fillet knife, Rapala for instance, mine have a very slight full bevel with a convex edge. 

Some do have a small micro bevel like from a hand held "V" sharpener. 

I may try something like that, though I'm afraid if I remove too much material I'll end up making it too flexible.

5 hours ago, Alex Middleton said:

I've made a couple of fillet knives from a bandsaw blade of a very similar thickness.  I put a decent bevel on them and buffed them to a shine.  They came out very well in my mind.  I also made a small kitchen knife from the same saw blade and put a full flat grind on it.  Talk about a slicer!  It was by far the sharpest knife that I've made yet.

Did you do a primary and secondary bevel or just a single one? I really like very thin knives, they can do a lot. I'm worried this might be a bit too thin. I'll probably leave essentially the initial finish on the flats so I don't lose too much mass.

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I was worried about the same thing, so I just did a single bevel on the ones that I made.  

Hand polishing the raw blade was a pain, they're not necessarily as flat as you would think.  I'm getting ready to make another set like this after I finish my KITH knife.   I'm going to put a full flat grind on it and see how it turns out.

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The thing about a flexible blade is that the edge has to be supported when it flexes. The convex is best for that IMO.

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That's a fair point Vern.  There's a good possibility that the full flat grind may not work on the fillet knife.  The little slicer I made had a more "squareish" profile to it which left more support down the length of the blade.  The tapered profile of the fillet knife would lend it to getting thinner and weaker the closer you get to the tip. 

I guess there's really only one way to find out.  I'll let you know in a few weeks.:D

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Sounds like the thin filet knife is a doable project. I'll see how the original finish looks, but I'll probably end up sanding it down/using one of my coarse stones. Probably test the hardness, see if it warrants re-hardening. I'm trying to get trained on some of the mat-sci equipment, so I may try to figure out what's in the saw steel just for fun. I'll probably get a design drawn at some point. 

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I took a little bit of time to draw up some designs, the first two inspired by Rapala knives, the third a more general design. Would love to hear what people think. One and two both have ferrules, though 1 would be a custom.

IMG_5612.JPG

I'm also debating the surface finish for the knives, I thought it might be cool to leave the original patina, though I don't want it to hold dirt. Another option would be sand-blasting to have some original finish without losing too much material. My final option would be to sand it down to a clean finish and do my typical satin knife.

 

IMG_5613.JPG

Here are some materials I came across recently, cork and spalter birch.

IMG_5616.JPG

I went into the woods with some friends to get the springs off an overturned car and we happened on a dead birch tree which turned out to have some very nice spalting. Will probably dry out small pieces in the microwave and seal the ends of the longer pretier ones for a propper seasoning.

IMG_5614.JPG

Also ordered some virgin cork bark to make saw/sand into slices to make a stacked handle from.

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I like the bottom one, kind of a mora/filet combo. As for finish if your food prepping get that baby shiny, I've had gastroenteritis from dirty water and it was horrible. Felt like an angry strongman with a barbed wire glove was fondling my intestines.....

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On 2/11/2018 at 8:41 PM, Jonathan Silas said:

I like the bottom one, kind of a mora/filet combo. As for finish if your food prepping get that baby shiny, I've had gastroenteritis from dirty water and it was horrible. Felt like an angry strongman with a barbed wire glove was fondling my intestines.....

Noted. There is some design/lettering on the saw I might try and preserve, maybe a scotchbrite finishing pad or something. Might just sand down to flat though. I may look into media blasting it, though if it's too aggressive, that could make a pitted surface which would rust/get dirty.

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9 hours ago, Aiden CC said:

Noted. There is some design/lettering on the saw I might try and preserve, maybe a scotchbrite finishing pad or something. Might just sand down to flat though. I may look into media blasting it, though if it's too aggressive, that could make a pitted surface which would rust/get dirty.

I love the scotch brite belts, they leave a great "Working" finish. I just end up with rounded bevels when I have used them in the past. I'm sure this has more to do with my inability to use them correctly rather than a design fault of the belt itself .

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8 hours ago, Jonathan Silas said:

I love the scotch brite belts, they leave a great "Working" finish. I just end up with rounded bevels when I have used them in the past. I'm sure this has more to do with my inability to use them correctly rather than a design fault of the belt itself .

If you’re very careful, you can finish bevels nicely, the key I’ve found is minimizing the amount of work you need to do with the scotchbrite (good prep), and keeping things flat. I recently discovered you can do a no-hand-sand pre-etch finish for low layer (deep etch) pattern welding. 

 

Unfortunately, I don’t have access to my grinder right now, so the scotchbrite might be done by hand. 

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Been a little while, but I've had this on the back of my mind. The shop here doesn't have a single good sander, but there is a very nice waterjet cutter, so I've been thinking about CAD files to get some pieces cut for this. Also have something in the works for the ferrules, more on that will probably come later. Made a 3D model of one of the designs, and tweaked it until it should (barely) float. It's hard to make a knife that's less dense than water!

Final Render 1.JPG

Final Render 2.JPGFinal Render 3.JPG

 

Next I'll probably draw up a model of the third design, and probably get both cut, maybe even a third, just since these seem fairly doable with my current setup.

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Very nice!  It'll be interesting to see how you tackle the ferrule.  Are you planning one piece or two?

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9 hours ago, Alex Middleton said:

Very nice!  It'll be interesting to see how you tackle the ferrule.  Are you planning one piece or two?

The plan is one piece, should be working a bit more on that this Wednesday.

Also, some renders of the other design, this time with matte textures for the wood.

Fillet 2 1.JPG

Fillet 2 2.JPGFillet 2 3.JPG

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Your files are a lot thinner than mine!  If it turns out like your models it'll be a show piece for sure.  Good luck!

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DD95B519-0460-4DC6-842F-BDA1D8AD46EB.jpeg

Just got these cut out on the water jet! Tested the saw hardness this morning at 45 HRC, not sure if I should re-harden them. Also, debating if I should do a primary/secondary bevel or a scandi. 

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