Composite Blade Sword II

T

TankEpidemic

Joined
Jan 31, 2013
Messages
37
This sword is made with a length of bi-metal band saw blade in between two pieces of carbon fiber, with the spine being 3 pieces of carbon fiber thick with each of the carbon layers being .055" thick and epoxied together with 8115 3M epoxy. This time around, the sword has a wider blade, 1 3/16" wide, and increased strength . The hand guard is made of magnesium and brass, as is the end cap on the handle. The handle is titanium tube sliced in half and wrapped with paracord. The blade comes in at 28", 36 3/4" overall.

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We also tried to bend the blade as far back as we could, but it is incredibly strong. This is how far we could bend it with just our hands. The blade does not stay bend and easily returns to being straight.
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Honestly I find the concept quite interesting, and think the sword looks pretty cool overall. I like the idea behind it and would like to see how it holds up to some cutting tests. My biggest concern would be the epoxy failing and causing delamination.
 
The last sword me made (found here: http://www.bladeforums.com/forums/showthread.php/1035293-Composite-blade-sword!) delaminated during some cutting tests because we did not assemble it correctly. The carbon fiber we found actually has a pattern pressed into to specifically designed for epoxy to set into and we only found this out recently. The last sword, we sanded on one piece of carbon fiber to see if it would affect it and how, and we figured scuffing it up would help the epoxy grab onto it. We were wrong and the carbon split from the metal. The first sword was also not heat treated(the curing process can be accelerated by heat) and we found that heat treating it made the epoxy stronger. We have conducted a few tests, cutting cardboard, water bottles, wood, etc. We plan to do some more, make a video and post it up here. If you have any ideas for tests we should conduct on this blade, please don't hesitate to suggest them. We wan't to find any and all flaws(if any) in this blade so we may better the assembly process. Thank you for your input, it is greatly appreciated. :)
 
Just curious about how you are going about doing the heat treat. I would think any true heat treating temp would destroy epoxy. Can you tell me how you are doing heat treat and at what stage of the build? May help me better understand the process.
 
The epoxy we use had a manual with it that said, "The curing process can be accelerated by heat with a heat gun or lamps." This epoxy is really great, it has a lifetime warranty with it and it is main used for bonding quarter panels to cars. We clamped the blade between two aluminum channels and ran heat from a heat gun down one length of the channel, bringing up the blade to around 160-200 degrees Fahrenheit. We do this at athe part of the build when we have all the pieces cut out in the rough shapes we want, then we start layering it and placing the epoxy on it. After that we get it into the clamping jigg we have and apply heat. It actually helps immensely, normal cure time is around 24 hours and we cut it down to around 2-3 hours with this process. The epoxy is a lot harder and bonds to material even stronger with the heat treatment as well. 3M really makes some cool stuff, including this epoxy. They would even pay for a rental car, pay you any money you may have lost from business due to your car being out of service because the epoxy failed to keep your quarter panels on. This epoxy is really tough stuff, paired with the carbon fiber sheets we have that have a pattern imprinted on them designed for epoxy to get into, this stuff DOES NOT come off. You have to grind it off to get it off anything it accidentally got onto and you might end up destroying whatever it is you got it onto.
 
I'd also like to put up here for the record, if anyone at all has any sort of ideas of tests they would like us to subject the sword to, please do not hesitate to post your suggestion here. We want to run some cutting and strength tests on this blade but our test do not vary by much.
 
So what I am understanding is that you heat cured the epoxy but did not heat treat the blade. Unles they were different steps. Was the steel pre heat treated or just left in an annealed state? If you mean you heat treated the blade with the heat gun that temp is not hot enough to even temper a blade back much less heat treat it. Heat treating takes temps usually over 1500 degrees with some type of quench depending on the steel type.
 
The steel had already been heat treated and such. The only reason we added heat was for the epoxy only. Sorry for the confusion. The steel is straight from a band saw blade.
 
Video tape Chopping a 2x4 in half
Suggest using a full Convex grind to zero and your cutting should improve dramatically.
Never have seen "Paracord" like that before. Like everything about it except the handle wrap has me a bit confused
 
For testing I would suggest the grass mats used by the japanese, tamishigiri. These can be found by mail order if you look. Also green bamboo if you can get a hold of any would be a good test.
 
have you guys considered (a) fasteners(s) to hold the layers together?
To my way of thinking, glue of any kind is not enough.

Laminated steel- forge welded together- has been shown to fail in some instances.

Catastrophic failure and carbon fiber is a BAD combination.

What do you think the best possible application of the technology that you are experimenting with is?

Have you researched other industries already employing laminated carbon fiber/epoxy/metal technologies?

The riskiest scientific endeavours often lead to the most significant of developments.

I feel that the field of carbon fiber/epoxy/metal laminates in cutlery is vastly under rated and largely unexplored, from a pragmatic perspective. Lots of 'stealth weaponry', but very little in the way of anything practical.

This technology would be very well suited to hunting and fillet knives. Large blades? I'm not sold.
 
What about drilling some small holes in the blade to facilitate "Epoxy Rivets" it will work.
Tried it on a few prototypes and held up well
 
Hankins, what sort of epoxy do you use? We use 8115 3M epoxy, it's guaranteed not to fail (when used correctly). It even comes with a lifetime warranty, though I understand that doesn't mean its indestructible. I also think this sword might be a bit delicate for 2x4s, but we will give it a swing if we can. As for the epoxy rivets, we have run into this idea with our first sword. The steel we used had a long pattern of slots along it's entire length. It didn't seem to help much in this situation, but we will look into it again and we will keep this idea in mind should the situation that calls for it arises.

Gregorio, those mats are pretty expensive, we are kind of on a budget and we aren't a big company. We are basically experimenting with the materials we found and have at hand.

Lorien, the application of the technology we are experimenting with is aimed at making the blades lighter and in some instances thinner. The camp chopper we made shows this more so than the sword. Since it is light weight, it does not rely on weight to generate momentum to carry it through material. Because of this, it takes less energy per swing to use the chopper and the velocity of the blade, in theory, could carry it through material better, if not equal to the momentum of a heavy blade. Not only can this sort of blade be aimed at hunting or camping situations, it can also be useful in military applications. Weight can be an issue when carrying gear, as well as being a factor in using it. We have not researched others using this sort of technology, though we were informed of two people who made smaller knives in this manner. We did make knives and shorter blades this way, but we wanted to push the boundaries of what this sort of tool could handle. We sought out to make a sword and now we have the desire to test it to it's limit. As a bit of a spoiler, we have a much larger sword in the works. I will be posting that one in the near future and I will be testing it as well. I should have mentioned this before, but this material is very expensive and we happened to have found a bunch of carbon fiber sheets in a surplus store for VERY cheap. We are merely experimenting with this idea we have, we do not have the intention to up the scale of production for profit. Also, in what way do you propose we add fasteners to this build? Can you please explain or give examples of what you mean? I would very much like to know if we could use some sort of fastening to better this sword and other blades.

Thank you all for your input, we greatly appreciate it and we hope you will still check back on our progress on these blades!
 
I respectfully disagree with your theory regarding weight and energy. I understand where you are coming from, but my experience tells me otherwise.

As for the fastener thing, just throwing the idea out there. I'm more interested in seeing how and whether you incorporate something like that in future efforts.
 
Well I've acquired the idea from katanas. People from japan at that time couldn't all wield large swords, so they made a weapon that relied on speed. European swords at the time depended on brute strength and weight to force their dull blades through objects. After a bit of thinking, I realize the sword we presented here is not a very suitable candidate to try and prove a point. We were trying to make an already light sword even lighter. I also understand that their are many other variables that gives the katana it's reputation as a good cutting tool (such as blade vibration frequencies, material used to make it, shape of tool, etc), but through my research and best of my knowledge, I've been told over and over that the katana was made to be lighter, and sharper, thus relying on speed and it's sharp edge to cut. It was made to suit the people in that area to their abilities. It may not be superior but it gets the job done in a different way and that is what we are trying to do with our design. We may post another thread with a different weapon model. Maybe a much larger sword that is more dependent on it's weight and strength. I would however like to thank you Lorien. Even if I am not right about my theory I very much appreciate your input. It is driving us to produce a better weapon or to learn something new about blades. Cheers. :)
 
I like the sword and the concept. You are seeking perfection and you will find it. Plus, you have experts here to help you along.
Try to stick with traditional blade shapes, if i may.
Rolf
 
I've been making metal core carbon fiber blades since I can't remember when... anyway a few years after I read about some of Warren Thomas' work in Blade.

Strongest way is to laminate the CF cloth around thin metal core (but not too thin... .0005 is too thin ask me how I know)

I agree with the 2 by 4 test. It can take a long time with a light knife.

As for a definitive test try some baton tests... this is extremely hard on the bond. Bend tests are not fair. A beam made of different materials with different elastic moduli deflects in ways that are most taxing to the bond. Add impact (rapid loading) for fun.

Most of this tech is well established, for example in skis, snowboards, archery. At the knife edge it is all taken to the extreme with very little composite available to support the edge.

Finally (for today) the orientation of the fibers in the laminate is of the utmost importance. Since I often hand lay-up I experienced composites that had good bending stiffness or good torsional stiffness but you cannot have both. You can move them around a bit, for maximum support here or there, or more torsional stiffness here or there, but the stiffness and strength of fibers is ONLY along their length.

Keep it up! I like seeing people work on this stuff and so very few are willing to test...
 
I do not think a 2 X 4 is a good test for this blade, I'd like to suggest you get a ham, or a leg of lamb, etc. I think you get my direction. You are making a light, fast blade who's primary application is cutting flesh. I would feel more comfortable if you got the metal properly heat treated for sword use. I believe the saw steel is tempered harder and will chip. Good luck.
 
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