Composite blade sword!

T

TankEpidemic

Joined
Jan 31, 2013
Messages
37
This is a sword my father made, its two pieces of carbon fiber material with a thin piece of steel between the two to hold the actual edge of the blade. The blade is 25" in length and 35" overall. It is extremely light for a sword of this length (as i almost cut myself from over swinging!) do to it not being comprised of metal as much as other blades, with the majority of its blade being made out of carbon fiber. The handle (although not entirely finished as the method of wrapping it is still in question) is made out of two pieces of titanium tubing cut in half and placed on either sides of the tang, then wrapped with the para cord.
tumblr_mhoq1ujTmf1s4msb4o1_500.jpg
 
I agree with Tinbasher.
What steel and how is the cf laminated/attached to it ?

Doug
 
tumblr_mhqdmbuzOb1s4msb4o1_500.jpg

This is another picture of the blade, though the light isn't the color I wanted it to be and its a bit hard to see clearly, but im trying to take another picture right now with some different lighting. The steel in the middle is stainless, but we are not sure what kind. It isn't very good steel either, its a bit of a pain to sharpen and it doesn't stay as sharp on the sword as it does on the knife I posted earlier. The steel was laying around and we used it to see if it would work, kind of as a prototype. We plan to experiment with a different steel later since we are now confident that the performance is good enough to proceed. As far as assembly goes, the pieces of carbon fiber are bonded on either side of the stainless steel with high performance epoxy, though we are not sure what kind of epoxy it is either, just some stuff laying around. If I can, tomorrow ill try to make a video of it cutting through some stuff, like some tough plants, cardboard, etc.
 
30 picture attempts later, here is a far better picture, you can see the layers of steel, epoxy and carbon fiber clearly. I have the picture hosted on tumblr and when you click the picture it enlarges it by a good amount, so if you wana see the pictures there, just ask and ill post a link to where they are at.
tumblr_mhqf3nxAWj1s4msb4o1_500.jpg
 
Yes the steel is pretty thin, but with the carbon it comes out to the thickness of a usual katana (can't remember the exact thickness). Lycosa, the blade cuts very well, however when trying to get video of it cutting taking some chunks off wood, we ran into a bit of a problem. One side with the carbon came off and split off the steel, but the epoxy will still not come off the steel due to improper assembly, but we can fix it. The blade is also only 1" wide, and it has some problems twisting as it cuts through material. So to fix those two problems, we plan to make another katana looking blade, make the blade wider and to taper the thickness between the handle and the tip of the blade. We are also going to experiment with making the epoxy bond to the carbon properly. The surface might need to be scuffed up a bit to provide a better surface for the epoxy to get into and grab on. I will have new pictures by the end of the day of the new blade, the latest by tomorrow. I'm also gona have to postpone the video unless you really want to see it. If you would like to see the videos I can post those in the meantime while I try to get this a second go.
 
The reason we found it was because the epoxy was not mixed properly. We have also got a hold of some 440C and we have a carbon expert helping us out on the project. I will post a reply and a picture when the next pre-production model is ready.
 
TankEpidemic said:
The surface might need to be scuffed up a bit to provide a better surface for the epoxy to get into and grab on.
Click to expand...

Absolutely. Surface-prep is the most important part of epoxying stuff together... especially in the absence of any mechanical fasteners.

A few small corby bolts down the length of the blade to hold the three layers together would help you tremendously.
 
Thanks a lot for the advise James, and for the compliment Lycosa. I really appreciate the support. Can't wait to see how it turns out so I can post the next update!
 
Maybe you could drill holes through the steel, where it is covered by the CF, then the epoxy would set throuh the holes and form a type of epoxy rivet to hold the pieces together?
 
The steel we used in this has long slots along the entire length. So there are plenty of holes. However, the only problem we had was that the epoxy wasn't mixed properly. Thanks for the input however, appreciate it.
 
Here is a picture of the jig that the sword is in as the epoxy cures.
tumblr_mhtxvjwLGI1s4msb4o1_500.jpg

Heh, think it's got enough clamps?
 
Last edited:
Here is a picture of the last few clamps being removed.
tumblr_mhv7fqwFtP1s4msb4o1_500.jpg


Here is the blade all finished, had all the clamps removed and is uncovered.
tumblr_mhv7btjO7G1s4msb4o1_1280.jpg


The carbon moved while the epoxy cured, but we are going to taper the blade to bring it together.
tumblr_mhv7g53sfI1s4msb4o1_1280.jpg
 
Becareful

Why are you using stainless steel.......especially 440 c for the core ?

Do you not think a carbon core and a clamping method that is a bit more uniform would serve you better

Good luck :)
 
Sorry to speak out of turn, but...

JParanee said:
Why are you using stainless steel.......especially 440 c for the core ?
Click to expand...

Why not? Like any other san-mai-type laminate, the middle layer/edge only has to be hard, not necessarily tough. That's the whole point.

Personally, I'd select CPM-3V or Elmax at 58-59Rc (possibly much harder, like 62Rc... that bears some pondering... ) for the core, but all the usual cutlery-grade alloys (stainless or otherwise) can accomplish the high hardness needed for the edge. Toughness and strength will be largely determined by the outer layers. I honestly do not know if CF is up to the task or not.

I'm assuming the steel core has already been heat-treated before laminating. Putting CF and epoxy in a kiln is a terrible idea. Using un-HT'ed steel is just as bad.

I agree that more uniform clamping -- even as simple as putting the whole thing between two boards, and then clamping the assembly* -- is a good idea.

I'm almost dead certain that without mechanical fasteners, it's going to peel apart sooner rather than later. No epoxy I know of can withstand shear/flex forces that will happen when the sword is used to chop and slash, especially when bonding wildly disparate materials. I could be wrong.

Fascinating project. I'm really intrigued to see how it works out.

*EDIT on looking at the pics again, it appears that the assembly was sandwiched between bars of steel during glue-up. That will surely even out the clamping pressure. :thumbup:
 
Last edited:
You must log in or register to reply here.
Back
Top