A device I saw demonstrated in a course on medical engineering was an exponentially tapering metal rod, with an ultrasound generator at the thick end. As the vibration travelled along the taper, it got more concentrated and the end the rod released all of the energy in a very narrow region. It cut through flesh like butter. One could imagine a knife working the same way: at the centre of the blade there is a piezoelectric array producing ultrasound vibrations travelling outwards. The blade becomes thinner and thinner, focusing the sound energy into a cutting plane around the edge. Note that with EP tech we can improve it quite a lot. Obviously the blade can be made from molecular-precision materials with very cool acoustic properties (laminated diamond designed to transmit ultrasound and resist cracking, for example). The generators can be smart about when to cut by having sensors detecting whether there is anything near the edge: if it is just air, there is no point in wasting energy. When cutting there will be reflected vibrations possibly harming the blade; adapting the frequency to the acoustic impedance of the surrounding material can protect the blade and make it better at cutting. I would probably put most of this regulation in firmware rather than software, because otherwise a hacker might just program the blade to shatter itself - although fully tweakable knives could also be programmed to use particular frequencies suited for particular targets, like the particular armor model the enemy is using. Another design would be a microscale chainsaw. Imagine taking a chainsaw and scaling down the teeth while increasing the speed, perhaps even having several parallel lines of teeth. Various smart control could make it able to avoid kickback or snagging on hard fibrous material. Nanomaterials allow very sharp teeth, able to separate materials with less force than wider teeth. However, there is a balance between teeth width and damage resistance: I suspect the ideal teeth width is not nanoscopic since they shouldn't break too easily when subjected to macro-forces. Having very small teeth also provides a smaller cutting area, but the scaling relations here get messy (I have excluded a paragraph of calculations here that didn't lead anywhere). However, for intimidation a loud buzzing and visible sharp edges are a must: maybe they can be generated by a separate system ("My muse flipped through the settings. Home-use added a yellow-black warning band around the edge, a safety volume in AR overlay and a sharp beeping noise. The street-fight settings mostly buzzed menacingly and showed sinister moving glints around the edges. The stealth mode was conveniently dark, silent and unmarked.") Incidentally, the idea of having the teeth change direction is probably bad since it would require a lot of energy dissipation inside the saw (done right it would likely end up like the ultrasonic knife above). But with nanoblades one could have alternating chains moving in opposite directions. This could induce some hefty shear forces that would tear many materials, keep the angular momentum to zero (easier handling) and only require one cutting edge per blade. Again, smart torque management is probably a must to make a blade that keeps. In the chainsaw case I can imagine a number of overlapping but small (a few millimetres) chains being run separately, stopping when not in contact with anything to cut and setting their torque depending on resistance. A truly complex (and likely over-designed) vibroknife might even remove damaged links and add reserve links while in use.

For the damage it does, the weapon would have to be at least the size of a short sword (if not a full broad sword length). No matter how sharp a knife is, it can't cut as deep as a sword and thus can't do as much damage.

Bloodwork wrote:

NoFace wrote:

If I was a designer, I would avoid anything involving a motorized chain if at all possible.

But they are so bad-ass!

And that is why Cold Steel Corporation sells the Mad Max Chainmaster telescoping butterfly knife! Only 39.99 credits and YOU can become the buzzkiller! In my game I would assume that "real" viroblades use ultrasonics. While the kind of people who want to be bad-ass use microchainsaws that fail in complex and interesting ways, but at least have that dentist drill sound (actually, it is synthesized) to really scare people. "Why do they call him teethface? Well, he tried to cut through a fullerene stanchion with his chainsword. The chains broke, the sword exploded, and he got all the diamond teeth embedded in the face. Makes shaving a bit of a challenge..."

I envision my character's vibroblade as 20cm plus standard human size handle - about the size of a contemporary survival knife. My GM let me have a lumbar quick release holster for it. I like to think that the blade is a nanofilaminent that rotates inside a very small channel along the edge when a switch on the handle is pressed, much like a chainsaw. This way, I have both a normal nano-edged blade OR I can flick the switch and do vibrodamage. I would think it needs recharging every 1 hour of use. The extra damage inflicted in vibro-mode is because it's easier to slice laterally - after the initial puncture, the blade effortlessly rips a gash. Just my 1/10cred...

Checkmate wrote:

NoFace wrote:

The 2d10 damage base is the origin of my question regarding weapon size. It is nestled between the knife, and the monosword. Plus it has a mechanical factor. It just wasn't clear to me what size weapon it was intended to be, and size is very relevant to melee weapons rules. I was originally inclined to conceptualize it as a knife sized weapon, and I still favor that interpretation.

The description shares more in common with a carving knife than a sword. You don't go around sawing things with a sword. Combined with the fact that its AP is twice as good as a knife but half as good as a monofilament sword seems to indiciate, to me at least, that it's simply a large knife. "Blade" is a word you usually use with knives more than larger weapons. If it were a sword, "vibrosword" would have been a much more apt name. And considering that the 'inferior' technology of a monofilament sword results in a weapon with stats noticeably better than a vibroblade... well, nuff said on the subject.

Vibroblades and monofilament swords use different mechanisms for cutting through objects, and vibroblades are most definitely [i]not[/i] just knives. Comparing them would be like comparing chainsaws to axes. Monofilament swords are essentially classic swords utilizing futuristic sharpening technologies; their edges are literally one molecule thick, and are quite possibly the sharpest possible edges you could ever possibly have on a cutting tool (unless we could make subatomic edges). A vibroblade, on the other hand, utilizes fast vibrations to essentially create super-friction, tearing through a target with a similar effect to a chainsaw. In fact, it's very likely that vibroblades, when shut off, are completely dull-edged just like a chainsaw. This is why a vibroblade continues to do massive damage if you hold it against a target rather than slicing or cutting like with a monomolecular weapon (in fact, a vibroblade does [b]more[/b] damage than a monofilament sword when sawing, 4d10 with AP -5 versus 2d10 + 2 with AP -4). Think of a logger cutting a tree down with a chainsaw... he doesn't hack at it.