I've been interested in making laminated blades out of carbon fiber and other exotic materials for about fifteen years. I finally decided to quit thinking about it and actually do it. Was inspired by the originator of this thread, and by some guy on Ebay who bills himself as a knifemaking pro and sells knives made solely of carbon fiber. He misrepresents the capabilities of (only) CF as a blade material, and his knives look like complete kaa kaa that could be made by anyone handy with a file, yet he must be selling them because I always see new ones put up for sale on Ebay for $100+(!). So, "If he can sell that crap...." I just had to get to work.
On the other hand, Warren Thomas sells his CF/Ti knives for between four and twelve times that much, but his knives certainly do NOT look like kaa kaa. I'd love to have one.
First thing I had to do was research: what materials to use and where to get them. I never seriously considered making blades solely out of carbon fiber, because of the poor edge-retention as pointed out by others. I thought about ceramic and still think it's a good idea, but I haven't been able to find the blade segments in a shape I can use and for a reasonable price. And yes I said segments. Ceramic is brittle, and stiff as it is CF is much more flexible than ceramic, so that could lead to a broken, possibly shattered cutting edge if you stress the knife too much. If your ceramic cutting edge is already pre-broken, in a manner of speaking, then you don't have to worry so much about it. I'd still love to try it out.
I also considered titanium for the cutting edge, like Warren Thomas and the poster above. I actually bought some so-called knife grade titanium (6ALV) and will use it for something sooner or later. But again, titanium is less than ideal for a cutting tool because it won't hold a cutting edge very long, at least as compared to steel. (As an aside, I'm also experimenting with laminating thick Ti with thin steel, but I can't get the two materials to stay stuck together. I think you have to etch the Ti first or something).
So I pretty much decided on steel for the cutting edge. It could be quite thin, since the only part of it I was interested in was the cutting edge anyway. Luckily, great material exists at a wonderful price: Sawzall blades. I bought some Diablo Liquid Metal blades and I'm currently working with making something from them (that's what I was trying to mate to the Ti). Stuff is harder than hell and a pain to grind or file, but that's exactly what I was looking for, hardness. Despite the hardness they're quite flexible because they're so thin. There's also the cachet of "Liquid Metal" steel, which is quite a buzzword (buzzterm?) in the knife field right now and could help if I ever decide to try to sell them. Like with all heat-treated blades care must be exercised not to overheat it while grinding because that will ruin the heat-treating and the hardness with it. Anyway, that's what my next laminated blade will be made with.
But before I got a chance to mate it with CF I found something that was so perfect for what I was trying to do that I (temporarily) dropped everything and started over. Clauss is a company that makes hunting knives with replaceable edge inserts. I was just about drooling when I saw them. And they're dirt cheap too. So I grabbed some.
Note: These things are harder than the Sawzall blades. I tried to drill some holes in one to give the epoxy some grip, and the drill bit just skated over the surface. Heavy added pressure broke the blade. In other words, they're ideal for my purpose, so long as I don't try to drill them. I was able to file them though. Slowly, patiently.
Epoxy: I wanted the strongest possible that I could afford. Of course there's aerospace industrial stuff that comes in buckets and drums and costs about a bazillion dollars and don't I wish I could afford some. But I finally settled on two, Aeropoxy and West Systems GFlex marine epoxy. The Aeropoxy looks like it's a little stronger, but I'm currently using GFlex solely because there's a West Marine store in my city.
Carbon fiber slabs: I looked all over and ended up buying a bunch from a guy on Ebay. Thought about buying the fabric and resin and laying it up myself, but properly made panels (like the ones I bought) are cured in an autoclave, which makes them much stronger than anything I could make on my own (who the heck has an autoclave--a big one--in their shop? Probably the same guy that has a DIY CNC mill.) Also had to consider the orientation of the fibers. Ideal I think would be 0 degrees (running parallel to the long axis of the blade, since that's where the greatest stiffness lies), and the least desirable a weave, though the weave does look nice. The stuff I bought was alternating layers of 0, 45, and 90 degrees with a final layer of weave on one side. These panels were not very uniform in thickness (by design not deficient quality control) and that has turned into a bigger pain in the old fundido than I thought it would be. As anyone who has worked with CF can tell you it's nasty stuff and the less grinding involved the better. In the future I'm going to buy CF in strips of uniform thickness, and orientation of 0 degree, from 1 to 2 inches wide depending on what I'm making. Good source here:
If I decide I want the weave look for cosmetic purposes I'll just buy the thinnest shiny panels I can find and epoxy them on as a veneer.
So I got all my stuff together and went to work. I ended up with an incredibly stiff knife that will shave hair, and weighs next to nothing. I'll give some details of the process of creation of my first CF blade in a subsequent post. Unfortunately I did not take pictures during the making of my first "exotic" CF blade (CF dust is not what you want on your cellphone or camera, something you will be holding close to your face), but I'll be happy to put up pictures of the finished product if someone will only tell me how to do it.
Don't forget, like I said this knife will shave, and it weighs very little. I could tote twenty of them around without noticing the weight. I'd have no qualms using it in a defensive capacity, and I've had some training in that area. For its mass/weight, it's pretty damn wicked. On to the next one, and I promise to take pictures during the process.
Not to hijack and old thread, but I find this information close to my heart. I started making carbon fiber motorcycle parts 7 years ago, and for the last 5, I have been in the composite industry. Last 4 years I have been lucky enough to be in the top research center for composite materials in the world. I will make anything out of carbon fiber that I can. For the longest time, I had a ring that I made one day.
However, I still have respect for the 6 micron fibers, and resins full of NASTY chemicals. I would NEVER EVER EVER get my food or drink near a composite part, unless it has been fully covered in an FDA approved resin (or plastic).....To see you making knives, and other utensils for human use is scary. I LOVE how you made the knife, it looks amazing. I might try it one day if I get bored. But would I cut anything I would eat later with it? God no. Think of the weird nasties in the epoxy that you are using. If any of the fibers chip/delaminate, they will be put into the food stuffs.
I am just here giving you a work of caution before you use any composite material near your food/body. If you are careful, you can coat/vacuum form a plastic sheet over a carbon fiber bowl. There is a line of safety there. But once that plastic layer gets cut.....watch out.
ps: again, love the work. As for inserting metal slabs for knife etch, sand the metal well (80-120grit) or sandblast them, so the resin can grab onto the metal, and not delaminate from the composite.