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Hi there! This is my first post and I'm Looking to make a custom Yari spear.

Although it's a pretty simple concept, I do not like the looks of mass produced spears online. And FULL custom spears from oustanding guys like Miller Bros Blades is really (really- really) expensive ...Therefore why not make a custom one. Goal: A really durable tactical fighting spear.

my concept:

***5ft ' 3in carbon fiber pole 
Diameter: 1 1/2" -filled with a wood pole thats 1.25'' in diameter 

I like carbon fiber and think it's a good material for practicing your forms while still being light and strong enough to hold its own against wood. Ofcourse not many recommend it since wood is proven true to be the best material (and theres a reason we still use wood bo staffs today folks). Good wood gives you Weight, sturdiness, flexibility in a staff. 
However, recently I got inspired by a thread i read at a different site about filling a carbon fiber pole (air tight) with a wood of some kind (like ash, wax, hickory,..etc.).

Blade : Custom 9" z wear pm steel / double edge blade. Pretty tough steel.
Overall Length: 6ft (I'm 5'11)

Other custom ideas like a "Reinforced Steel end cap" and "steel braces" on each end will be worked on as the setup gos.

What are y'all thoughts on this? Might turn out just as cool as it will be fun. Also could use some tips on how the blade can be secured in the tubing without looking Tarzan made lol.

P.s. I'll attach images of what i want the spear to look very similar too. Its a full custom spear made by Miller Bros Blades.

(The spear tubing from the photos attached are also carbon fiber but hollow.) 

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13071692_1177240808975890_8672676341452846258_o.jpg

13071770_1177240762309228_2330793855567568746_o.jpg

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19 minutes ago, ThomasPowers said:

What are the aging/wear characteristics of the material you will be holding in your hands?

 

Thanks for the reply!

"Polymer materials when reinforced with high modulus fibers yield higher strength, higher stiffness, better toughness, and good dimensional stability. Fiber reinforcements are effective in reducing wear in adhesive situations in addition to increasing the strength and stiffness. The adhesive conditions are generally encountered in automotive and aerospace applications." - From what i read online.

Almost think of carbon fiber like the the handle of a baseball bat. They can take a pretty good abuse even when made contact from an inside fastball.

The wood on the inside will vary. At the moment leaning towards wax. Heard its tough and flexible. But never felt it.

bamboo: splinter 

japanese oak/ maple: solid but heavy and less flexible 

Hickory: solid but not flexible.

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So no problems with repeated impacts causing fibers to protrude and getting jammed in your hands as you run them up and down the shaft?  Good!

Though none of what you posted addressed that...Most baseball bats seem to have something else covering the grip area; use of a spear will involving running your hands over most of the shaft.  A key point of quality is: "do your metrics address what's actually important?"

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Thanks again. You're very right. I was so focused on making sure the staff doesn't break I didn't consider the idea of the outer-splinting.. This all new to me and my very first project. (: 

I wonder if a different piping should be considered.. Or obviously a better understanding of carbon fiber lol 

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I am not aware of the characteristics of the stuff you are looking at---I just know from experience some issues seen with other types of spear shafts.  For all I know you could use shrinkwrap tubing over the outside and avoid the issue; but I don't know the uselife in that use or weight issues (or cost issues), etc

 

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I hope this isn't going to be your first ever project. it would be a learning experiance. if it is your first time blacksmithing start with some more simple projects. my first project was a railroad spike "knife" and I wish that I would have started with something easier, though, it was a lot of fun!

                                                                                                                Littleblacksmith

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Thank you for a response and no this isn't. Helped my dad and grandpa a lot on machete 5150 steels throughout my years of college. Turned out pretty good. 

The shaft is my main inexperience while the steel will be co-forged with more experienced hands. 

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sounds good.

                                                                                                        Littleblacksmith

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Carbon fiber composites tend to have poor damage tolerance, particularly due to impact. 

The below article discusses the findings from a workshop with respect to the damage tolerance of carbon fiber reinforced composites in 1986 (i.e.,after the carbon fiber reinforced composite components in 4th gen. tactical aircraft were designed). I have included a relevant quote. 

http://www.sciencedirect.com/science/article/pii/0263822386900255

" The main conclusions to be drawn from the workshop are: (1) damage from impact is the worst type of damage for these materials—significant reductions in the compressive strength will occur following impact; "

Please also consider the application of carbon fiber in road bicycles. If they didn't tend to fail so catastrophically (and somewhat unpredictably) after relatively minor wrecks, many more cyclists would use them (My cycling nut best friend included).

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Blue Duck,

That's an interesting conclusion, and I can appreciate your points regarding bicycle frames.  I'm curious how arrow manufacturers are able to make carbon shafts that are significantly tougher than wood or aluminum for impacts.  I should mention that most commercial arrows have a warning on every shaft to do a bend test before firing them every time.  The catastrophic failure of an arrow shaft at full load can seriously injure the archer.

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Not so sure they are any more durable than wooden arrows, but they don't wharp and have smaller crossections. 

Ash and hickory are infact flexible, as is several other "bow" woods, bambo was historically used for staves, spears and arrows because it is light, strong and the right shape with minimal work, bambo composite may be an interesting choice, as would rattan. 

A peice of fiberglass sucker rod coverd with heat shrink would be tough as all heck but still a bit heavy for a spear, bambo filled with foam might be pretty slick as well, cromolly tubing with a balsa wood core might be the ticket, if you are concerned with it being hacked in half (TI tubing would be lighter) 

everything has its trade offs... 

 

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I don't think that the impacts on the arrow shaft are typically the same kind as those a bicycle frame in an accident, or a spear shaft parrying another weapon.  Certainly there is some side pressure from the bending an arrow makes on release (see slow motion archery for this, pretty interesting), but it should be rare for an arrow shaft to have side impact that stresses the bond between the composite materials, or breaks fibers.

Wouldn't the traditional Yari shaft be something like rattan?  Why not just use that?

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While this is an interesting discussion I don't think the OP stuck around after finding out we don't think it's a very workable idea. If carbon fiber were good for taking point impacts they'd be making body armor from it and not just using it as the frame and backer to carry loads and disperse energy.

It flexes wonderfully well, see an arrow video or a bow or such but don't bend it over a sharp edge or subject it to high localized forces. All the materials in the composite are very strong but they all react differently to stresses. In some cases this makes the whole stronger like pre-stressing rebar in concrete structures. The problem is carbon fiber is a whole different kind of strong than epoxy. A steep differential in movement causes shearing and one breaks the other in failure.

I haven't seen any, and it's been decades since I worked in an aircraft rubber connector plant so I don't know if carbon fiber and phenolic resins are even compatible. I made a lot of phenolic resin impregnated 7 oz. fiberglass cloth (not mat) Bell helicopter engine duct parts. The duct parts were IIR about 2 3/4" dia. un-bonded lap jointed cylinders made using 2 plies on the bias wrapped and heat cured. There were rejects and trimmings of course so I got to experiment a little.

VERY heat resistant, Bernzomatic torch proof no sweat, barely smoked. There wasn't anyone in the shop who could open one of the tubes and bend it over backwards. We took a couple to the desert target shooting and a lousy 2 plies of 7oz fiberglass cloth impregnated with phenolic resin would stop bullets from all out guns up to the .30cal M1 Carbine and stop it dead cold with a bare minimum of crazing in the resin. The 30 06 firing military hard ball punched through as did the 8mm. Magnum but soft nosed mushrooming hunting bullets were stopped by the stuff.

The cylinders were a little thicker than a cardboard shoe box.

Carbon fiber or not my vote is for phenolic resin impregnated if you want something that'll take unholy abuse.

Frosty The Lucky.

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Rockstar, Latticino and Frosty nailed it. The shear forces between plys make impact hard on composites.

I don't know much about composites with a one-part thermoset matrix, but I could see how phenolic would be a good one. I always regret it when I mess up a metalographic mount and have to break my sample back out when I use the phenolic. Some of the newer composites use thermoplastics like PEEK as well, so the fiber and matrix could likely be tailored to the application. 

I really like Mr. Stevens' idea with the bamboo. I have been wanting to plate some bamboo with the stuff in the links below (with an appropriate intermediate material layer for adhesion) for staves and bicycle frames. 

http://www.integran.com/services/plating-on-composites/

http://www.integran.com/products/ultra-lightweight-structural-parts/

Edited by Blue Duck Forge
Corrected a name misspelling.

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