DIY fully carbon fiber knife building. :) Lots of pics!

[liveforphysics]

I bought some carbon fiber materials to make some fairly complex parts with, and sadly realized that I was badly lacking the skills needed to make complex things.

So, I decided to try some simple things first to teach myself a bit, and trying a knife seemed like a simple and fun first try.


I know you knife building pro's are 10000x better than me, and I know my shapes I just eye-balled for the blade shapes and handles etc are nothing amazing. This was just an exercise in working with CF for me, rather than the quest for building the worlds most amazing knife.


So, I picked through some of the pics that turned out decent (all just done on my cell-phone cam :sigh.

The first set of pics is for the thick and long bladed knife I made, which turned out to be really over-kill on blade stregnth, and kinda silly how thick it was. The second set I went with 1/2 the blade thickeness, and it still feels so rigid that flex seems almost undetectable in it, and it slices veggies and things much better with the thinner blade section.

I used my DIY CNC machine to rough-out the strip to become the blade from some 1/4" CF.

Then I ground it and wet sanded it into a shape I liked.

Then I measured up my hand vs the tang material I left, and decided how big to cut the scabs to laminate into being the handle.

Then cut them out with my CNC.

Laid them all up to make sure I was happy with how thick it would be. I used 2x2 twill weave carbon for the blade and inside area of the handle, and then used a slick 1x1 checker board weave for the outside layers of the handle. I think the design contrast is pretty slick.

I mixed up a batch of the special fancy-pants epoxy in the special ratios, and mixed it in the recomended way to avoid bubbles from getting mixed in, then coated both sides of each piece, stacked them all together on a big chunk of solid teflon, and applied weight with another big chunk of teflon.

Patiently waiting for the stack to cure well enough to go in the oven for final hardening...

Once it all cured, I started the filing and sanding process. Dry sanding the carbon was pretty bad, but wet sanding with fine grits, like 600-1000 worked very well.

Hours and hours of sanding later.... and I had something I was proud of.

 

[DaFABRICATA]

EXCELLENT JOB!!!

And the pics are amazing for a cell phone!

NICE WORK!! Keep it up!!

 

[liveforphysics]

The next week, I started another knife, this time with the thinner blade, because the first knifes blade was just way stiffer and stronger than I could ever imagine it needing to be.

Then rough ground it.

Then cut out the handle laminations, laminated them, cooked in the oven at 300f over night, and this is what it looked like.

Trimmed off the ugly with the bandsaw.

Then I started in for a few hours of file work...

Then, another few hours of wet sanding, and I had another knife I was proud of. This one just feels damn good in the hand, and I got an edge good enough on it to slice tomatoes easily, and it seems to do a pretty good job around the kitchen.

 

[ninemm]

Pretty cool knives! Nice craftsmanship. :thumbsup:

 

[Chauncey Gardner]

They came out pretty nice

I'd like to make some CF scales for some of my knives & may pm you later.

 

[Anto]

WOW

that's awesome

 

[liveforphysics]

So, some neat things about CF is that it's never going to rust, or be bothered by saltwater or things left on the blade.

It's so light, I can have it loose in a back pocket, and even jogging I don't even feel the thing. I haven't weighed them yet, but I think they are under 1oz per knife. They almost feel like holding air, yet they are extremely rigid.

No metal means metal detectors won't make you give-up your knife, though these perticular ones are too big for EDC (at least to me).

They look really cool just dry in normal room lighting, but in sunlight when wet, they are hard to even take your eyes off! When I'm slicing up fruits/veggies at the kitchen sink with the sunlight comming in through the window, the knife is so distractingly awesome looking, I've actually cut my fingers from paying more attention to the knife than where I'm cutting.



For people looking to make there own, it's pretty easy. I spent about $400 initially in materials to get the proper carbon fiber epoxy, a small roll of cloth, and some pre-glued carbon fiber strips. I've got enough materials left to make at least 4-5 more knives, so the materials cost is really not too bad, well under $100 a knife for all materials involved if you're going to make a few.


I'm sure the knife making guru's could do the grinding and sanding in under a couple hours, and it would be all perfect. For me, it was the bulk of the time in making each knife.

I estimate I've got about 10hrs of work from start to finish for each knife.


I hoped you liked seeing how it's made

-Luke

 

[liveforphysics]

Thank you for all the kind words guys.

 

[csshih]

nice work!

 

[liveforphysics]

For the people wondering how CF holds an edge, I can tell you it's nothing like good steel.

I can cut soft things with them, like veggies and fruit and trim steaks and things with no issues, and the blade stays sharp.

However, if you start trying to carve wood or hacking through cardboard boxes and things, the blade does lose it's edge very quickly, and hacking at harder things puts tiny little knicks in the blade that a good steel knife would have taken no damage at all from.

It has it's ups and downs as a material. It would certainly make a poor machete, but it does seem to make a fine kitchen knife.

 

[liveforphysics]

Well, I cut some thin Ti blade blanks to wrap in carbon fiber, but keep the cutting edge of the blade as exposed Titanium.

But... then a guy at the EDC forums made an excellent suggestion! Use a piece of ceramic for the cutting edge insert!

Now I'm shopping ceramic blanks, and trying to get the best material money can buy for the cutting edge strip. From what I've read, there are ceramics for knives that can be sharpened well beyond the capability of any steel knife, and hold an edge as much as 60 times longer! The weakness is of course the tendency to break the blade if used to pry or dropped on the tip etc.

A ceramic cutting edge inset into an extremely rigid carbon fiber blade/handle should really help over come the weaknesses of the ceramic knife, while the ceramic cutting edge over comes the weakness of the carbon fiber knife. And it keeps the perfect chemical/salt/rust resistance, keeps it entirely non-metalic, will still be 1/8th the weight of a similar steel knife, and can be made sharper and hold an edge better than any steel. I don't care if it costs me $200 for the damn insert, I now must build my vision of the most perfect knife ever!

 

[A380]

WOW!! Great work. They are really nice.
Just one safety note, CF dust is very dangerous if it get into your lungs. Better if you get a mask (if you don't use it) when you sand CF.

 

[an0nymous]

Ok. Wow. Yer ceramic cutting project is completely cool. Looking forward to those pics.

 

[RepProdigious]

Then I started in for a few hours of file work...

You were wearing proper safety-gear when doing this i hope? The dust and flint coming off CF is really really nasty and especially the fine dust doesn't get filtered out by regular masks.....

Apart from that; Nice job! Are those knives legal in your country?

 

[liveforphysics]

Ok, here are some crude pics of my crude testing with laminating metals into the carbon fiber. I'm using Titanium here, but it's only to practice the process of getting the carbon/insert/edge layout laminated to meet my standards for stregnth and visual qualities rather than trying to make knives, so don't go making fun of my stupid triangle blade shapes. They are just test mules to cut apart and pry with and flex and see how things hold up.
You can see I refined the methods on knives 5 and 6 to grab the blade with CF rivot-like shapes. I counter-sunk the holes on both sides, so each little carbon plug has fibers running long-ways down the blade, and through the holes. The result here was a CF/Ti blade that I wad able to fold at about a 45deg off-axis in the vise before the carbon started to crack away from the titanium. You can see the plug shapes in the blade I cut-away as a sacrifice to see how well the plug-insert method filled in with carbon, and I was pleased.

 

[liveforphysics]

BTW- That Ti blade in the last picture I sharpened enough to shave with, and when you mess up and cut yourself with it screwing around, it actually doesn't hurt. You're just surprized to see blood dripping from somewhere and wonder where you got knicked. lol

 

[FNinjaP90]

Very nice! Can't wait to see the carbon ceramic knife.

I made a lot of stuff during school with carbon, and I also made myself a spoon. Highest stiff:weight spoon ever.

 

[liveforphysics]

Beautiful spoon!

 

[RepProdigious]

Thats the nerdiest, hyper most tacticool and overdone spoon i have ever seen...
















I want one

 

[FNinjaP90]

I'm currently doing graduate research on microscopic void analysis on vacuum-assisted resin transfer molded carbon fiber laminates embedded with multi-walled carbon nanotubes.