Shardblade Calculations

[SteelShaper]

So I'm a blacksmith [helps with pocket change while in grad school] in my spare time, and I've been thinking about the dimensions of shardblades and what they might weigh.  I promise to keep the math low key here.

Let's start by establishing the dimensions of a hypothetical shardblade.  For this exercise, I'll use a shardblade with a 70 inch [American] blade, 2.5 inches wide for most of its length, with a 12 inch handle.  I'll convert this to metric for later calculations, but not just yet.  Based on the geometries of historic weapons, just the blade and tang [yes I know shardblades are solid, but I'm breaking this down the way I would if I were figuring out how much of each material I would need if I were actually building something like this] would add up to about ~18 cubic inches.  This figure accounts for the bevels from the spine of the blade to the edges (double edged design), and for a taper along the blade from 1/4 inch [at the spine] near the handle to 1/8 inch [at the spine] at the tip.  

For figuring out the handle, pommel and guard, to account for sharblades being solid, I'll subtract the 2.8 cubic inches that make up the tang from the blade total.  If the crossguard takes up 1/2 inch of the handle space, and extends 5 inches to either side from the center of the blade, assuming a square cross-section for simplicity you have 2.5 cubic inches there.  Now, let's assume a maximum diameter (and this is squiffly, because handles have tapers in two directions, and other design peculiarities dependent on design, and I'm trying to keep the math simple here) of 1 inch for the handle.  Factor in the shape of the handle, [no, I'm not going to show that math] and you have ~10 cubic inches.  Add a pommel, call that another 2 cubic inches.  So, the blade is 15.2 cubic inches, + 2.5 inches for the guard, + 10 inches cubed for the handle, + 2 inches for the pommel, gives you a grand total of: 29.7 cubic inches of material in your shardblade.  

For my non American metric lovers, that equals 486.7 cubic centimeters.  

Now, as said in the books, this blade could never be made out of steel, not and be usable.  Steel has an average density [depending on alloy] of 7.86 grams per cubic centimeter, so if it was made out of steel, this blade would weigh 38.25 kilograms, or a whopping 84 pounds!!!  For comparison, a standard broadsword shouldn't weigh more than 4 pounds.

Okay, so what are the other options? Titanium has a density of 4.51 grams per cubic centimeter.  A titanium shardblade would weigh almost 22 kilograms, or about 48 pounds.  That's better, but still not exactly usable.  If it were made of pure aluminum, at 2.6 grams per cubic centimeter, it would weigh in at 12 kilograms, or 26 pounds.  That is much, much better-- still not great, you would have to be really, absurdly buff to swing it more than a few times, and mind, once you get it moving it sure as all get-out isn't going to stop, but still, we are at least getting into the realm of possibility now.

Thankfully, aluminum is not the lightest metal around.  Unfortunately, most of the alternatives tend to be a little unsafe, whether that means flammable, explosive in contact with water, or just plain toxic or radioactive.  Your best bet for getting something about close to the right weight, as seen in the books, would be potassium or lithium.  Potassium is 0.89 grams per cubic centimeter, lithium 0.53.  So a potassium shardblade would be 4.3 kilos, or 9.4 pounds, while a lithium shardblade would weigh in at 2.58 kilos, or 5.7 pounds.

So, lithium has the closest weight to what is described in the books.  So, yeah, if you can find that much lithium, you could make a usable shardblade.  Except it would bend, wouldn't take an edge, would dent left and right, and oh yeah.  Don't get it wet, or your priceless shardblade will disappear in a flash that will leave you with permanent retinal damage.

[Frustration]

So Shardbatteries are a thing now.