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I was talking to Jason at Underground Tactical Arms about the world’s first 3D printed metal gun. [Click here for TTAG’s review.] The gun’s manufacturer (Solid Concepts) is based in Austin, along with precision guided rifle manufacturer TrackingPoint. I suggested that Austin has become the silicon valley of firearms. I wondered what kinds of new and different firearms could be created with a 3D printer, given that the $600k machine can produce prototypes in days and create parts that injection molding machines can’t. “You want to talk about revolutionary,” Jason said. “What about a railgun?” Turns out that the University of Texas at Austin’s Center for Electromechanics is building them for the Army, Navy and Marines. They’re not hand-held. Yet. But remember that lasers used to occupy entire rooms. Now, not so much. The laser rifle above may not be practical, but someday, it will. As always, watch this space.

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  1. The problem with lasers and railguns is the power source. Lasers particularly. They are only like 5% efficient. You are changing chemical energy to electrical energy then again to photonic/light energy. Compared with simple firearms (which are very efficient).

    Unless a new power source can be made these will never reach the point of a personal carry weapon. Unless you can drag Val Kilmer out so he can get started on “lasing a stick of dynamite”

    The energy output for a laser or a rail-gun would have to be unbelievably large to reach the abilities of a conventional cartridge. Modern day batteries – just can’t deliver this.

    • You can get some pretty high powered lasers in handheld sizes, power’s not as much a limiting factor (or, at least less proportionally THE limiting factor). Railguns, by nature, are always going to be relatively large and heavy. Beyond the power source, you need a capacitor bank, and then the rails themselves require length. I’ve considered modifying an M-2 tripod when/if I try to build one.

      • I haven’t tried to build a rail gun… so I don’t know. I do know looking down the length of the rail gun you have concentric inductors. The energizing of these inductors (either by air core or iron core with an aperture at its center) has to be perfect for the most efficiency and it is not linear as the ferromagnetic projectile is accelerating. I would think you would need a capacitor bank (if that is the design route taken) for each inductor as a single bank would be immediately discharged (by short circuit). The banks would have to be tremendously large and the projectile would still not have the same force as that exerted by the pressure of an explosion behind it. The only hope to achieve a decent energy is a heavier, larger projectile moving a lower speeds. Such a projectile would likely not have good external ballistics compared to a traditional firearm. Also you would be carrying a tremendous amount of controller boards, capacitor banks, and the power source hasn’t even been mentioned. Also, the time required to recharge your banks could take some time. This could be very harsh on modern day batteries and it would take time to recharge the banks according to the time constant (RC) of the system. Your resistance is very low, but your capacitance is very high and the recharge rate is exponential – e^-t/(RC). Cyclic rate would likely be very low. It feels to me the technology is very far away.

        • Are you talking about a coilgun instead, with staged electromagnets? I’ve seen some of these on Youtube, but not sure I’ve ever seen a railgun with the projectile completing the circuit between two energized rails outside of military research.

          Some of the big SDI railgun prototypes pumped a million amps across a copper film at the back of the projectile. The copper flashed into plasma, and completed the circuit to the tune of nearly 10,000 fps muzzle velocity. Barrels eroded quicker than a .220 Swift, though.

        • I’ve looked into a few garage-built systems, what has and hasn’t worked for other hobbyists, etc. It’s a linear motor, pure and simple, and a “true” “railgun” is named such because the projectile runs along two rails, with (as a general rule) the projectile itself completing the circuit. And yes, that’s a decent bit of oversimplification. I’m not looking to build a weapon as much as a proof of concept. I think you need a genuinely big gun before you start to see gains over the limits of traditional propellants, anyway.

          As far as the power supply itself, some form of dedicated generator is generally recommended. Time between shots would be slow, which is why I’m considering two cap banks, so one can charge as the other is waiting to be used. Which would also double the weight of that part of the total (and require a switching assembly).

          It’s a several year project, I’m not trying to do anything that hasn’t been done before, but my thoughts are along the lines of, “Why not?”

        • Yes. I was talking about a gauss (coil) gun it seems – we discussed it’s design back when I was in school. I mistakenly saw this for a “rail gun.” In a gauss gun the projectile once accelerated actually never comes into contact with the sides. I see the true rail-gun is much simpler, with a block of metal (doesn’t have to be ferromagnetic) completing the circuit of two rails and relying on the lorentz force for acceleration. Seems very simple to operate and make. Either one though, there is the power requirement. Almost need a small powerplant to operate one. Capacitor banks are expensive and limited. I’d try a flywheel based energy storage system that dumps into the railgun or coils.

          Anyways, I think you guys should get started. Build some. Make some videos with a chrony. Then send to TTAG so we can all watch.

        • even though I was an EE, I was never really interested in coil or rail guns. But lately I have been thinking a lot about gasoline guns ;). Its a gun with a magazine full of bullets (not cartridges). The chamber is large to accommodate a fuel mixture and a spark plug. I first thought of it years ago as a small personal weapon with a small battery (for the spark). Think of it like a car engine – except the cylinder is long and open on one end 😉

          Think of it… cast bullets go in… fired bullets go out. No brass, no primers. There are complications though. The bullets would need to be longer for better concentricity at the throat.

        • One problem I could foresee with a gas gun is that it still involves combustion of a propellant in a chamber, so the ATF could claim jurisdiction (as they did to Daisy in the ’60s with their primerless, caseless .22, though I guess you’d be theoretically safe without mass-production). I can think of some other issues involving the pressure as well. If you could figure out some way to build a blow-out disk into the projectile, you’d have a head start. Maybe the projectile fits tightly into the chamber, then moves to a less restrictive barrel? The trick would be getting it to trigger at the same pressure every time.

          My experience is more practical than theoretical (read: I have no degree, but a lot of hands-on time), but I am a full-time student at present, which gives me access to facilities and experts who can help fill in the blanks. I’ve considered a small-scale coil gun in the past, but for what I would be able to build for a relatively small budget, I could buy a Red Ryder and enough BBs to wear it out. Thinking about it, I’ve got a break coming up to run some numbers, an upcoming semester to harass faculty with non-curriculum questions, and a whole summer to do the actual work. I think I’m going to look into something decidedly smaller scale than my previous plans. I wonder what kind of muzzle velocity I can get using a hand crank power source…

    • It’s been a long time since I got my BSEE, so if anyone see’s a mistake please correct/advise.

      A 124gr 9mm bullet is traveling at 1200fps @ 382 ft*lbf (518 Joules) and strikes a soft target. It strikes and stops in this target almost instantly. We are going to assume 10 milliseconds (it is probably less than this).

      Now compare with a laser. We need to deliver 518 Joules of energy in 10 milliseconds (for equivalency’s sake). Power (watts) = Joules/seconds. So 518J / 0.01 seconds.

      This is 51,800 Watts. Lets assume it is a really good laser and is 15% efficient. That means 345,333 watts are required to deliver one shot. This is the power required for the system. The best method that I can think of for this kind of delivery of energy to protect one’s self, is the system we already have employed (A controlled explosion accelerating a projectile).

      • Well said. There is also the issue of beam divergence. To be effective, a portable laser must concentrate a high amount of energy in the space of about 1.5 – 3.0 mm. My 200 mw 532 NM green laser has an effective range of about 3 feet on matches and less than 25 feet on black balloons. Even a high powered IR laser (I’m guessing this is between 1-3 watts) with the tightest available beam divergence would probably not have an effective range longer than 25 yards.

        I am estimating because I don’t know the initial beam diameter, divergence rate, or output level of this particular IR laser.

        Also, a laser such as this must be continuously aligned with the target for a period of several seconds or longer. That target must be within a few millimeters, or the result will simply be a superficial burn. It’s difficult for me to even burn a house spider with my 200mw laser because it will move continuously.

        Still, a cool concept.

        • Were someone to actually produce a “weapons grade” man portable laser it’s not just the lethal aspect that makes me shudder, it’s what a laser would do to any unprotected eyes (including yours) that happened to be in the area. And people thought stray bullets were a problem.

          If the medical community thinks the trauma from a bullet is bad, wait until they have to start dealing with deep tissue laser burns.

        • The ability to lase and blind opposing troops was Darpa’ed out decades ago. AFAIK, it was never deployed, but the blinding effects are well known and well, if it can be weaponized, gosh darn it you know we’ll at least look into it.

      • Thank you.

        There are times when I (a retired EE) want to break out the engineering analysis on some gun spec or some wish item one sees here and there on the interwebz (which I’m told by an august US Senator is a “series of tubes”), but in the end, all I can do is reach for another beer and, while drinking said beer with one hand, face-palm with the other.

        It’s good to have more engineers ready to break out the math.

  2. 2 or 3 generations of nerds from now this will be something that politicians will insist only criminals have access to.

    • Actually, there already are some rather strict limits on the strength of lasers civilians are allowed to buy and own without justifiable reason. I think it’s somewhere around 2W, since that’s the strongest Wicked Lasers offers.

      • I dont think so. i know certain types of lasers are regulated but not illegal to own.
        IR lasers for example. Civilian DBALs are eye safe class 1. That didnt keep me from getting a 50mw version, totally legal.
        And ive got a 4w handheld green laser, Wicked just hasnt come out with more than 2w yet, dont think its any restrictions. They are still class IV

        • I’ve never looked into it too hard, so I just did some quick searches. What I found is that laser regulation falls under the jurisdiction of the FDA, which is scary enough in itself, but I also found nothing on power limits (other than 5mW as a maximum if the product is being sold as a “pointing device”). I just figured, with their history of pushing legal limits, that if there was some sort of regulation Wicked would have a product that just barely conformed.

      • knightofbob, Not sure what country you reside in but it sure ain’t ‘Murica.

        Here we can drop a few hundred and grab a 200W CO2 laser on ebay. One with a power supply and modulation control and what not is significantly more dinero, but there are absolutely no purchasing regulations on any of it. Yet.

        • As I said above, I was mistaken, I’ve been corrected, and did a little more research. Though, in my research, I did find it is illegal to brandish a laser pointer near law enforcement in several states (technically, “point at,” but it’s your word against theirs) and federally an issue if you point your laser into the air and it’s detectable in FAA airspace (technically, again, it’s supposed to be about intent, but you prove the you didn’t mean to have that green laser directly in the flight path of a private jet that came through three hours after you did so). As far as your 200W CO2 laser on ebay, I’ve found some parts for a few hundred, but thousands for actual lasers, and tens of thousands for anything operational.

        • Sorry wasn’t trying to be harsh on you, that’s just a really common myth and drives me insane.

          A “laser” is a part, (very)vaguely like a lightbulb, one still needs the power supply, controller, cooler, mirrors, lenses, and other doodads depending on what you’re doing. Which can be expensive, as I noted. Mea culpa, I did typo in the wattage – a 200w laser (once again just the bulb) will set you back $1500ish, but a 100w (which is what I meant to type) will be $500ish.

        • As a result of one of your comments on another thread about DMLS and lasers, I started investigating lasers, prices and what not.

          Let’s keep you anonymous, because soon, my wife will want a word with you about my “new hobby.”

        • DG, I’m sorry. (But I’m kinda not). A prof in the Glove State just went public with his $5K-ish metal printer. Which ‘natch carried all the “concerns” about printing guns in the press releases. Oh well…

          Dig around a bit and you’ll find the hobbyists. I’ll stay in the shadows, as I have enough trouble with my women without adding your SO to the list…

  3. Austin TX is more likely to become the first TX city to ban guns. Its pinko heaven for crying out loud.

  4. In the hands of someone willing to do harm to a great amount of people….These things are pretty terrifying devices.

  5. I can hear it now:
    Hold still please Mr. Criminal … I can’t keep my laser dot on one spot long enough to do anything if you don’t hold still!

  6. Dear Santa,

    If/When this is perfected in the future please put one under the tree for me!


    PS- We both know I have been a very good boy

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