Building a Full-Auto Gauss Gun

Okian Warrior writes "Adding to the 3-D printed gun/rifle controversy, Delta-V Engineering built a Full-auto Gauss gun (aka 'machine gun'), capable of firing 15 steel bolts from its magazine in less than two seconds. At 3% the muzzle energy of a .22, it's still in the prototype stage. Bullets are made from turned-down nails, and the gun uses no chemical propellants. The builder has posted the design notes online. Video of the gun in action is pretty interesting."

Comments

Re:hi

[Anonymous Coward]

It's so great Slashdot allowed G+ and Facebook logins so we could get even more spamming and shill posts than we used to get.

Sensationalist summary at all?

[tocsy]

"Adding to the 3-D printed gun/rifle controversy"

How? Neither the Hack A Day article nor the design notes mention "3d" or "printing," and the fact that it's a gauss gun implies that metal is pretty central to the design... which can't be 3d printed at this point in time.

Re:Sensationalist summary at all?

[Anonymous Coward]

Oh yeah? Well just wait till I 3D-print a nuclear bomb, and then we'll see where your total indifference to the perils of people having access to such a dangerous weapon truly are!

I'm only glad you've not pried my AK-47 from my cold dead hangs, at least if the Zombies come, I'll be able to fight them off.

Re:Sensationalist summary at all?

[ganjadude]

actually there are metal 3d printers. they are just not as common and generally not what many are speaking of when talking 3d printers at this point in time. I just did a quick google search and found this one fvor example http://www.3dsystems.com/3d-printers/production/spro-125-direct-metal

Re:Sensationalist summary at all?

[bmk67]

Not only that, but this isn't even legally a "gun" under U.S. law.

Re:Sensationalist summary at all?

[bobaferret]

you can 3d print metal FYI..

http://www.3dsystems.com/3d-printers/production/spro-125-direct-metal#.UgKVbkBDtIM

http://gpiprototype.com/services/metal-3d-printing.html

Just some quick google search results on on the topic of "3d printer metal"

Re:Sensationalist summary at all?

[i kan reed]

While I agree, I think the underlying tie here is that "fully automatic" has, until this point, been something that requires industrial design and manufacture to incorporate into a design. It's not a trivial thing to do, and requires a fair amount of precise moving parts for weapons with chemical charges.

Re:Sensationalist summary at all?

[fuzzyfuzzyfungus]

"Adding to the 3-D printed gun/rifle controversy"

How? Neither the Hack A Day article nor the design notes mention "3d" or "printing," and the fact that it's a gauss gun implies that metal is pretty central to the design... which can't be 3d printed at this point in time.

It's doubly sensationalist because Gauss guns (and railguns, though this isn't one) are both technologies beset by the 'If I had a source of nearly-unlimited current with a rise time of ~0, and a supply of superconducting magnets (or, for railguns, unobtanium rails with heroic resistance to welding/resistive heating damage), I could totally fuck you up!' problem.

If you handwave the electrical issues, magnetic accelerators are all kinds of scary. If you don't, you'd be lucky to cram the power supply for anything actually dangerous into a single support vehicle...

Re:Sensationalist summary at all?

[h4rr4r]

Why would you think that?
You can make a fully automatic submachine gun of the open bolt design out of stuff you can find at home depot.

Re:Sensationalist summary at all?

[gstoddart]

If you handwave the electrical issues, magnetic accelerators are all kinds of scary. If you don't, you'd be lucky to cram the power supply for anything actually dangerous into a single support vehicle...

Unless your support vehicle is an Aegis cruiser or some such thing.

The military is always looking for new and improved ways to lob shit on people from long distance.

Re:Sensationalist summary at all?

[i kan reed]

Yeah, as long as you don't mind the heat from firing to bleed down into your cartridge.

Re:Sensationalist summary at all?

[tocsy]

I... was completely unaware of that - I suppose a simple search would've told me as much. I don't see anything about price though, so who knows if it's actually available to individuals or if you'd have to be super rich to get one.

Re:Sensationalist summary at all?

[h4rr4r]

You don't know what firing from an open bolt means do you?

It means that the firing pin is part of the bolt face or fixed onto it and the bolt slamming down on the round is what fires it. In most simple designs the bolt is then thrown back by the round discharging. This design as you can likely now guess vents a lot of heat and as such tends to avoid overheating.

Re:Sensationalist summary at all?

[g0bshiTe]

Yes because in WWII they didn't have the technology to make something as simple as a Sten http://en.wikipedia.org/wiki/Sten

Re:Sensationalist summary at all?

[i kan reed]

I didn't say modern industrial design.

Re:Sensationalist summary at all?

[h4rr4r]

You should just admit you were wrong.
Stens are one example of an open bolt automatic that are easy to build and do not require precise moving parts.

Re:Sensationalist summary at all?

[JaredOfEuropa]

The printers are dear but there's a few fablabs around where you can have your design printed in metal, at a reasonable cost.

Re:Sensationalist summary at all?

[ganjadude]

from my understanding they are at the early adoptor phase, so not generally availible to the masses yet. normal plastic 3d printers are still pricey so the metal ones are a few grand more expensive. cheepest one ive seen was about 11K

Re:Sensationalist summary at all?

[gl4ss]

sterns work just fine for warfare. it's a crude design but works. of course you can't go on shooting 1000+ rounds in one go but with few guns can you do that anyways, barrel will go bust before the rounds popping in the magazine.

Re:Sensationalist summary at all?

[i kan reed]

Eh, it still requires machined materials. I'm not entirely convinced of the argument. But no, let's just pretend it's all nice and settled.

Re:Sensationalist summary at all?

[h4rr4r]

http://thehomegunsmith.com/pdf/BSP-SMG_Book.pdf

Machining can be done with a file, this is largely how Khyber pass guns are made.

Give it up already.

Re:Sensationalist summary at all?

[jxander]

While it won't feed directly into the "3D printed" part of the controversy, this is still arguably a fully automatic rifle (aka "assault weapon") that someone built in his spare time, at home. (depending on your definition of what exactly constitutes a gun ... launching a handful of nails at 90 mph is painful, but not terribly deadly)

And of course, this is hardly the only gun someone has ever made at home. From zip guns to STEN, and a lot more can be made in the comfort of your own home... and that's not even taking into account the possibilities if you happen to own a drill press.

But all of that is moot in today's society of 24/7 shock and awe news that borders on terrorism in and of itself. "Home made assault weapon with scary sounding name : GAUSSIAN!" will make the rounds on news networks, probably with pictures of the killer robot future from Terminator. And politicians will glomp onto the scare to pass more 2nd amendment crippling legislature. We need a hacksaw registration database! Ban magnets, I don't even care how they work.

Re:Sensationalist summary at all?

[Medievalist]

3d metal printing on demand was invented at roughly the same time as plastic printing, in the mid-1980s. I think the first ones were sintering, but now there's several other methods. Go look at wikipedia.

But anyway 3d metal printing has been available to the unwashed masses for quite a while now. It's not cheap, but it's easily done if you've got the simoleons.

Shapeways was offering stainless steel printing with 21 days lead time at $10 per cubic centimeter to pretty much anybody by 2009, and nowadays you can even get titanium printed objects without any major effort. Don't bother building a printer, just email your design files and a valid credit card number to one of the vendors.

Re:Sensationalist summary at all?

[h4rr4r]

It is not a rifle, as it lacks rifling. It is not a firearm under US law.

Re:Sensationalist summary at all?

[Anonymous Coward]

It is not just about the costs though, as there are still material issues that can make them less useful than hoped. Some metal based 3d printers produce something from powdered metal that would be a fair bit weaker than something milled from a solid piece of the same material, as the material is almost porous or has some sort of filler. Others use a casting technique to fill in or replace the printed part, which can also be quite a limit to what alloys are used. Depending on what you are doing, there could still be a substantial deficiencies from cheap, off the shelf alloys that can be used in conventional subtractive machining.

Re:Sensationalist summary at all?

[Defenestrar]

I'm certain ASTM will have additive alloy specifications soon (if they don't yet) and people will be able to make quick smart decisions about their manufacturing process. Many existing alloys have recommended post fabrication treatments (i.e. heat: anneal, temper, etc...; chemical: pickling, anodization, etc...) which vastly improve certain characteristics which would have been detrimental to the shaping process. Additive materials will probably be similar.

Re:Sensationalist summary at all?

[CAIMLAS]

"3D printed guns" is just a bunch of media gathering hype and bullshit.

With the most rudimentary tools, people have been able to produce firearms much more serviceable than these dangerous plastic devices. People have been making AKs using not much more than a hot fire and a couple smooth stones for almost 50 years. Simple blowback operated machine guns similar to the WWII Sten can be made in a garage with scrap metal, a dremel, and a piece of rusty pipe, or 'bangsticks'.

It's not difficult and requires very little skill or resources; blueprints are easily found online for those who can't figure it out on their own. This arguably easier than the 13-shots-before-blowing-up 3D printed guns which cost thousands in resources and require a great deal of knowledge.

If people are scared of 3D printed guns, it's because they either don't understand the limited implications, or they're just reactionary idiots. 3D printed plastic guns were never meant as anything more than a political statement.

Re:Sensationalist summary at all?

[Cramer]

I was thinking the same thing. While there are metal printers, they, and their output, are super-expensive. And there's ZERO reason to go to all that expense.

For the record, I built the same thing (a "rail gun") in high school, in 1988. Obviously, they have access to much better batteries today -- we used car batteries -- and fancy electronics -- despite doing this in an electronics class, ours was far more low-tech (blob of mercury(!), garden hose, and a series of pins... whip the hose and a nail goes flying through a 2x4.) Their system appears to have limited range, no stability (the nails are tumbling 99% of the time) and thus low penetration. [I still wouldn't advise standing in front of it.]

It's a good start to the latest chapter in their FBI file.

Re:Sensationalist summary at all?

[CAIMLAS]

What criteria does it not meet for being a firearm?

(3) The term “firearm” means
(A) any weapon (including a starter gun) which will or is designed to or may readily be converted to expel a projectile by the action of an explosive;
(B) the frame or receiver of any such weapon;
(C) any firearm muffler or firearm silencer; or
(D) any destructive device. Such term does not include an antique firearm.

That's from USC 921. There are many similar definitions in US law; some are even so as restrictive to be inclusive of propelled air or mechanically propelled weapons (eg. BB guns and slingshots).

Re:Sensationalist summary at all?

[jxander]

You know that. I know that. Does Fox news know that? Do they care?

Re:Sensationalist summary at all?

[lgw]

How about a working AK-47 made from a shovel and a home forge.

Inventing an automatic weapon is serious engineering. Following a design (especially one designed around sloppy tolerances like the AK) just isn't that hard. For a less labor-intensive solution, CnC milling machines will do the job from a simple program at manufacturer quality (or better) today.

There are interesting legalities to all of this, but given good legal advice and a blueprint you could likely start from iron ore and a tree, and make a working AK.

Re:Sensationalist summary at all?

[bmk67]

"expel a projectile by the action of an explosive"

That part.

Re:Sensationalist summary at all?

[Cramer]

Actually, NO. Semi-auto firearms are slightly complicated mechanical designs. They are inherently "fully automatic", but their design incorporates elements to halt the cycle.

Making a full-auto firearm requires paperwork and licenses. It is a felony for anyone without such to fabricate a full-auto firearm (or alter/convert to full-auto) -- even discussing it is illegal.

Re:Sensationalist summary at all?

[vux984]

It only needs to meet any of A/B/C/ and D, not all of them.

Based on the ridiculous definition presented, a jar of live termites could be classified as a "firearm", based on it meeting the threshold of:

"a destructive device"

Re:Sensationalist summary at all?

[bmk67]

Read more carefully. There is far more law that goes into the definition than what is presented here as well.

A) It does not meet this definition.
B) Must be a part of A) - does not meet this definition, either.
C) Isn't a muffler or silencer (which are defined elsewhere) - doesn't meet this definition as well.
D) "Destructive device" is also defined elsewhere, and no, this does not apply.

This isn't a firearm under federal law any more than an air gun is.

Re:Sensationalist summary at all?

[CAIMLAS]

Correct me if I'm wrong, but when using this device, a bullet, from a loaded cartridge, gets propelled down a barrel by action of the explosive powders in the cartridge.

Re:Sensationalist summary at all?

[vux984]

Correct me if I'm wrong, but when using this device, a bullet, from a loaded cartridge, gets propelled down a barrel by action of the explosive powders in the cartridge.

No. It does not.

http://en.wikipedia.org/wiki/Coilgun

A series of magnets propels a projectile.
There is no explosive powder. There is no explosion.

Re:Sensationalist summary at all?

[vux984]

A - agree
B - agree
C - agree
D - not disagreeing - but as excluding it required reference to terms defined elsewhere which I did not have, it is reasonable, based just on what we had there to conclude it applied.

Re:Sensationalist summary at all?

[gl4ss]

just call it non destructive.
nailguns aren't firearms.
neither is a sling made from your belt.
your hand isn't a firearm.

bows aren't (controlled) firearms either.

Re:Sensationalist summary at all?

[i kan reed]

You can make a microprocessor too, with the right expertise. To pretend that basic handi-working skills are all that's necessary is extraordinarily extreme.

  This is clearly off-the-shelf components with designs an idiot could follow.

Re:Sensationalist summary at all?

[flink]

nailguns aren't firearms.

It depends. Some nail guns for use on concrete use an explosive cartridge to drive the fastener. I think that might qualify them under (a) above.

Re:Sensationalist summary at all?

[gandhi_2]

Not really.

Closed bolt machineguns require fairly precise contrivancnces to make the firing pin strike at the right time during the cycle of function. This includes most Automatic Rifles and Submachineguns that must have select fire capability (semi, burst, full. for example). In some cases, precise headspace is a factor also (how close the bolt face is to the breach when the firing happens), or the machinegun must have a variable headspace. The M2 .50 cal has variable headspace AND timing. Semi autos aren't just fully autos with something to stop them for this reason.

If an M16 (or M4) was allowed to go full auto without a "disconnector", the hammer would be allowed to fall too early in the cycle. Best case would be failure to fire (cartridge not fully seated on bolt face yet), worst case would be an out-of-battery detonation with hot brass fragments flying out the ejection port.

Open bolt machineguns, (M60, M249, M240, et al) are more like as you describe. The operating parts (including the bolt) would be more than happy to run away until the belt ran out if it weren't for that damn sear holding them back. Open bolt machineguns are not to be fired semi-automatically. Even purposely single-shooting them (unless only loading single rounds) wears down the sear and can lead to a runaway gun.

Re:Sensationalist summary at all?

[gandhi_2]

Well to be honest. "Gaussian" does blur the lines a bit.

ba dump bump!

Re:Sensationalist summary at all?

[rullywowr]

Correct me if I'm wrong, but when using this device, a bullet, from a loaded cartridge, gets propelled down a barrel by action of the explosive powders in the cartridge.

Apparently you didn't RTFA.

Additionally, it seems you never played Doom or Quake and have not heard of the term "rail gun" before

No explosive, or "loaded cartridge" required.

Re:Sensationalist summary at all?

[bmk67]

Attempting to understand the meaning of laws without understanding what legal definitions apply is a bit naive, IMHO. Particularly firearms law, unless you like prison. EXTRA particularly NFA, unless you like getting killed.

Re:Sensationalist summary at all?

[bmk67]

Correct me if I'm wrong

OK, you're wrong.

Re:Sensationalist summary at all?

[bmk67]

Possibly. The ones sold by your local tool/hardware store are not legally classified as firearms. If the store filled out a form 4473 and did a background check, it's safe to assume that it is.

Re:Sensationalist summary at all?

[amicusNYCL]

the fact that it's a gauss gun implies that metal is pretty central to the design... which can't be 3d printed at this point in time.

Oh, what sad times are these when passing ruffians can say "3D printed" at will to old ladies. There is a pestilence upon this land, nothing is sacred. Even those who arrange and design guns are under considerable economic stress in this period in history.

Guns are my trade. I am a gunner. My name is Roger the Gunner. I arrange, design, and sell guns.

Re:Sensationalist summary at all?

[Anonymous Coward]

It is not the lack of specifications that is the problem, it is that there is another constraint added onto whatever other material constraints a project has. For many projects, it might not matter, especially given the wide variety of geometry it enables. For for many other projects, the raw strength of the material is what going to matter. New specifications won't help if you are using some sort of powdered metal process that cannot achieve 100% fill of the desired metal. I've run into problems before that were not easily solved by alloys appropriate for casting, but when the geometry is simple enough it takes only a couple minutes on a mill, that isn't normally an issue.

Re:Sensationalist summary at all?

[lgw]

You lost me with the point you were making. The toolchain for a microprocessor is huge. The toolchain for making an AK47 is a good design and a source of decent steel - sheets to form the receiver and a forged tube for the barrel. Precision machining (precise beyond measure-carefully-and-drill) is only important if you want interchangeable parts, which is all-important for an army, but much less so for an individual.

Precision machining is also quite important for long-range accuracy, but that's a different gun than what we've been discussing.

Re:Sensationalist summary at all?

[chihowa]

"expel a projectile by the action of an explosive"

That part.

Interestingly, if you used an explosively pumped flux compression generator to deliver the current to the gauss gun, would it meet the definition of a firearm?

Driving the gauss gun this way has its advantages: very high current and very low rise time. Of course, the disadvantages pretty obviously outweigh them.

Re:Sensationalist summary at all?

[Zynder]

While I agree with the overall nature of your post, that last line amounts to 'move along nothing to see here' and we both know that answer is usually just a handwaving distraction. Who decided 3D guns were just a political statement? I never heard anyone but you say that. No, what we see going on right now is good old fashioned hardware hackin going on. These first weapons are being built to see what the limits of the craft are at this moment. As you mentioned, they suck. Do you honestly believe though that we are just gonna go, oh well it sucked ass so we'll throw the technology away? Of course not! Us stubborn humans are gonna keep pushing the limits, redesign whatever piece didn't work right, make us new plastics that will take the abuse, and so on. The 3D printer is one prerequesite technology to having a real life replicator! The ultimate goal is not politics, no, it is a fully functional device that will print out whatever the hell we want, weaponry included. I, for one, cannot wait to own my replicator!

Re:Sensationalist summary at all?

[cavehobbit]

Each state also defines what a firearm is. In NJ air-guns, (compressed air, co2), are considered firearms. Purchasers must go through the same permitting process as firearms owners do.

But at least you won't put your eye out with it.

Re:Sensationalist summary at all?

[cavehobbit]

As I noted up-thread, air guns are considered firearms in NJ.

It is not just federal laws that must be considered.

Re:Sensationalist summary at all?

[fuzzyfuzzyfungus]

The navy does have a railgun R&D program, presumably because their support vessels are that big (and, if the power supply demands can be met, magnetic accelerators can do things that chemical propellants can't).

It's just that the smaller you try to make the system, the more likely it is that some asshole is going to point out that you are carrying a 50kg power supply with multiple-seconds-between-pulses charge times to provide the same amount of energy (assuming a 100% efficient coilgun) that is provided by a single 5.56mm cartridge...

Re:Sensationalist summary at all?

[bmk67]

The majority use the federal definition. NJ being a notable exception.

Re:Sensationalist summary at all?

[mjwx]

http://thehomegunsmith.com/pdf/BSP-SMG_Book.pdf

Machining can be done with a file, this is largely how Khyber pass guns are made.

Give it up already.

This, cheap weapons can be made in back yards with rudimentary tools. They can be mass produced without much machining at all (Al la the STEN linked to earlier, it was mostly pressed from sheet metal).

However quality firearms are not so easy to make, guns like the Sten which were very cheap to manufacture tend to have a lot of problems (the STEN had a lot of loading/feed issues, especially if held by the magazine).

So if you just want to get a cheap, no-nonsense sub machine gun you can easily do it from unskilled labour in a impromptu workshop. If you want a SMG that will work no-matter what, it's a bit more difficult.

Re:Sensationalist summary at all?

[CAIMLAS]

More an ideological statement than a political one, but yes, the guy who started this current "3D printed gun" craze the media is in by releasing working 3D printed gun blueprints on the Internet for free about a year? back - it was an ideological move for him.

On the other hand, weapons tend to push technological capabilities pretty quickly, they're fun, and a natural target for the engineering-oriented (and often male) mind. "How fast/hard/strong/etc. can we make it?"

I highly doubt a replicator is anywhere in our lifetimes. We're struggling with laying down layers of plastic at a slow rate and making it cost effective. I highly doubt we'll be anywhere near a cup and Earl Grey, hot.

Re:Sensationalist summary at all?

[rtb61]

Actually the whole gauss gun idea makes no sense. Take an electric motor attach a say 100mm diameter spinning frame put you bullet on one side with a counter balance on the other side spin it up to 2000 revolutions per minute and you achieve 628m/s when you release the bullet. You could use the gauss equivalent barrel just to add a final bit of acceleration but more importantly control aiming. Obviously accelerating the next bullet for firing is tricky but if added at the centre and allowing for centrifugal force to take it out to the circumference whilst added resistive force to slow it's progress to the circumference and all the while maintaining counter balance (otherwise aiming would be difficult) you can high velocity full auto fire. The bigger the circumference the higher the velocity whilst limiting needed revolutions per second.

Re:Sensationalist summary at all?

[semi-extrinsic]

They're not in "early adopter phase" by any means. My university has had a similar device for almost ten years. They are, however, in the "holy shit that is insanely expensive" phase, and will likely continue to be so in the foreseeable future.

Re:Sensationalist summary at all?

[semi-extrinsic]

Obligatory pop-cultural reference http://www.youtube.com/watch?v=JDpvkwBBu6U

Re:Sensationalist summary at all?

[semi-extrinsic]

if the power supply demands can be met

Yeah, for navy applications, the LM2500 gas turbine or the A4W nuclear reactor are usually able to do that.

Re:Sensationalist summary at all?

[TheRaven64]

The navy likes them because space is at a premium on a large warship, but with a nuclear power plant energy is not nearly as scarce. If your ammunition is 20% propellant, then a rail gun will let you carry 25% more ammunition for the same space, and that lets you engage in combat for longer between resupply runs.

Re:Sensationalist summary at all?

[Kilo Kilo]

Remember, this is the same country who's lawmakers like to throw around the term, "assault weapon." If it's a projectile weapon that remotely resembles a gun, then it's too scary for the masses and must be heavily regulated.

On a side note, a bed sheet is not a proper back-stop. And those hipster glasses aren't safety glasses. If you're going to shoot things, do it safely.

Re:Sensationalist summary at all?

[wagnerrp]

Railguns and Coilguns operate in two completely different fashions. The only similarity they have with each other is that they both use electromagnetism.

Re:Sensationalist summary at all?

[delt0r]

Rail guns use magnetic fields like coil guns. But in a very different way. In particular the projectile itself is part of the circuit.

Re:Sensationalist summary at all?

[chrysrobyn]

Actually the whole gauss gun idea makes no sense.

I think it makes lots of sense. It's pretty clearly functional and simple, and it runs off the definition of a linear motor. In fact, there are some places that will assume "projectile" when you specify "linear motor" instead of slower speed ideas (like a MagLev).

Take an electric motor attach a say 100mm diameter spinning frame put you bullet on one side with a counter balance on the other side spin it up to 2000 revolutions per minute and you achieve 628m/s when you release the bullet.

Did you build one of those yourself to satisfy your own curiosity? If not, then I don't think you have any business stating that a coil gun makes no sense. When someone explores your idea and discovers a 10cm flywheel that's counterbalanced until the moment of release, what kinds of problems are they likely to encounter at the moment of release? 2000 rpms sounds pretty reasonable in terms of my car engine, but I might get nervous about that close to my face. How noisy is a 2000 rpm flywheel that is centripetally loaded? How much energy is involved in that strategy? How long is the initial spin-up?

Personally, I think the coil gun ideas are far more simple to understand and instead of mitigating drawbacks at every step, he's shooting aluminum cans and glass jars and a laptop he apparently has a great deal of animosity toward.

Re:Sensationalist summary at all?

[i kan reed]

Oh look, a petulant angry gun person who can't control their temper. Thanks AC.

Re:Sensationalist summary at all?

[Eivind]

What happens to the balance of the wheel when you release the bullet ?

Re:Sensationalist summary at all?

[vux984]

Gunpowder doesn't explode, it just burns very rapidly.

For the purposes of the discussion here that's just semantics.

Re:Sensationalist summary at all?

[lgw]

Hahaha! Yes, how could I forget.

Re:Sensationalist summary at all?

[pspahn]

Shovel gun thread... best thread ever.

Re:Sensationalist summary at all?

[Zynder]

I highly doubt a replicator is anywhere in our lifetimes. We're struggling with laying down layers of plastic at a slow rate and making it cost effective. I highly doubt we'll be anywhere near a cup and Earl Grey, hot.

I WANT TO BELIEVE

Re:Sensationalist summary at all?

[neonKow]

There is never an explosive powder. Gunpowder doesn't explode, it just burns very rapidly. The primer is the closest thing to an explosion in a gun and it's pretty weak, it's just used to ignite the gunpowder.

Also, gunpowder isn't really gunpowder anymore. We switched from black powder (charcoal, sulfur, and potassium nitrate) almost a century ago. Modern smokeless propellants are very different in composition. The only common factor may be some form of carbon source and a nitrate.

Burning rapidly is literally the definition of a low explosive. Your use of the word "explosive" is closer to the definition of "detonation".

Also, your use of "correct" is closer to "pedantic."

Re:Sensationalist summary at all?

[Medievalist]

I'm pretty sure metal sintering existed before lasers... Wikipedia says the Egyptians were doing it in 3000 BC and I know for sure that the pre-columbian Inca were doing it routinely. And despite the claims of UFO nuts concerning Pumapunku, I don't believe the ancients had laser technology.

AFAIK the early 3D metal sintering printers of the 80s didn't use laser sintering - but honestly I could be wrong. I haven't researched it at all and wasn't involved in the early research and development, everything I know is hearsay.

Thanks for the titanium price checkpoint!

Smaller projectiles?

[Anne_Nonymous]

Why not use smaller projectiles at a faster velocity?

Re:Smaller projectiles?

[Jane Q. Public]

This was my thought as well. Those projectiles are far too massive for what he's trying to do.

While I haven't done any calculations, it seems to me that a projectile a fraction of that size would be accelerated far better and thus have far greater muzzle energy.

TFA claims it has 3% the muzzle energy of a .22, but it would appear to weigh 10x or more what a .22 slug weighs. Making it smaller and increasing its velocity could massively increase that energy. (If, just VERY rough figuring, you made it 1/5 the weight, it should achieve far more than 5x the muzzle velocity, which could give it (depending on the actual numbers) 10x the energy, bringing it into a range that is halfway respectable.

Re:Smaller projectiles?

[h4rr4r]

How fast can those coils run?

My guess would be he is near those limits so a lighter projectile would not travel much faster.

Re:Smaller projectiles?

[suutar]

To get 10X muzzle energy he has draw 10X the energy from the batteries, which means more batteries, which harms the portability goal. To get 5X muzzle speed increase, the coils have to power up and down 5X as fast, which probably requires more smaller coils and probably other circuitry speedups, which requires more complicated circuitry, which increases cost and reduces maintainability. Sure, his design requirement for muzzle power isn't much; a flintlock musket has 25x as much muzzle power. But it's still a pretty nifty build.

Re:Smaller projectiles?

[Anonymous Coward]

From "The Maths" section of the builder's website:

"The most frequent comment I get on my coilguns is that I should use a lighter projectile to improve performance. This equations [sic] shows why that suggestion is wrong. It’s counter-intuitive, but for a fixed power and distance (e.g. fixed capacitor bank and coil), a lighter projectile will gain less muzzle energy than a heavier one."

Re:Smaller projectiles?

[lgw]

Other have pointed out the math there is wrong - output energy is bound by input energy. I wanted to add that for actual solid rifle bullets, the damage they do tends to track momentum, not energy. While yes its the energy transfer that causes harm, rifle bullets usually over penetrate, and as it turns out the actual energy transfer is usually proportional to MV (by a roundabout path). So using the same energy to fire a heavier bullet slower is generally more deadly, until you get it too slow and it stops acting like a bullet (which is admittedly the case here).

Modern militaries like lighter bullets moving faster, because you can carry more rounds when they're lighter. Of course everything's a trade-off, and the tide seems to be moving now to heavy bullets moving just as fast, since long infantry marches haven't been important for decades, so why not just carry more.

Re:Smaller projectiles?

[Jane Q. Public]

"To get 10X muzzle energy he has draw 10X the energy from the batteries, which means more batteries, which harms the portability goal. To get 5X muzzle speed increase, the coils have to power up and down 5X as fast, which probably requires more smaller coils and probably other circuitry speedups."

I think that's an assumption, not the reality. I'd give you 10 to 1 odds that he is not controlling the "power up" curve of the coils at all, but rather hitting them them with full (but timed) power pulses. The only thing that would change is the timing of the coil firings, not their overall energy.

But I grant that I do not know that for sure.

Re:Smaller projectiles?

[Jane Q. Public]

"The most frequent comment I get on my coilguns is that I should use a lighter projectile to improve performance. This equations [sic] shows why that suggestion is wrong. Itâ(TM)s counter-intuitive, but for a fixed power and distance (e.g. fixed capacitor bank and coil), a lighter projectile will gain less muzzle energy than a heavier one."

But he ALSO writes this:

"Note that equation 3 assumes constant acceleration, which is a close approximation with a highly multi-staged coilgun. Begin by eliminating t by feeding equation 3 into equation 2 and re-arranging to solve for E."

That is a really HUGE assumption for a short, 8-stage coilgun. As he says, "it is a close approximation with a highly multi-staged coilgun". Which his is not. The logical conclusion then is that this is not a close approximation for his version.

Another thing he mentions is that the efficiency goes way up as the projectile velocity increases.

Re:Smaller projectiles?

[myowntrueself]

since long infantry marches haven't been important for decades, so why not just carry more.

Probably not since the Falklands...

Re:Smaller projectiles?

[wagnerrp]

Coils don't power up and down instantaneously. It takes (a small amount of) time to build up field strength, and when you turn it off, there is some lingering field retained in the materials. Beyond a certain point, you simply cannot accelerate it any faster. The only option is a longer barrel, or a railgun which sidesteps these issues by not being pulsed.

Re:Smaller projectiles?

[wagnerrp]

You can't fire a heavy bullet just as fast because you wouldn't be able to handle the recoil. Just watch someone trying to fire an M-16 fully automatic, versus someone trying to fire an AK-47. As for heavier, slower bullets doing more damage because high speed ones penetrate too far, armies are investing in body armor, which means penetration is a good thing, and modern rifle bullets are aerodynamically unstable, meaning as soon as impact with a target screws up that spin stabilization, they yaw violently and fragment, similar to a hollow point round, maximizing the energy that is transferred to the target.

Re:Smaller projectiles?

[lgw]

and modern rifle bullets are aerodynamically unstable, meaning as soon as impact with a target screws up that spin stabilization, they yaw violently and fragment, similar to a hollow point round, maximizing the energy that is transferred to the target.

Did you know that's a lie? It was propaganda printed by the US government and distributed to our troops in Vietnam to help gain acceptance of the M16, which was seen by many as a toy gun (many parts were plastic, it didn't weigh much, Mattel was involved in manufacturing). The M14 simply had more stopping power, and was more accurate at range. The M16 was based on design assumptions that a lighter gun and lighter bullets would make the soldier overall more effective with a given carrying capacity, despite each shot potentially being less effective, and the realization that almost no casualties occurred at ranges where the difference in accuracy mattered (and history has proven that largely correct).

watch someone trying to fire an M-16 fully automatic, versus someone trying to fire an AK-47

An typical AK-47 is amazingly inaccurate to begin with - but in urban combat typical range is so short it just doesn't matter. A better comparison would be an M14, which was infamous for the wildness of its full-auto fire. The weight of the weapon matters a lot, too - an M249 is far more stable in auto fire because it weighs over 20 pounds fully loaded.

As for heavier, slower bullets doing more damage because high speed ones penetrate too far, armies are investing in body armor, which means penetration is a good thing,

Sure, but armor penetration is mostly about energy (well, and the details of the projectile), so at a given energy level most mass vs speed tradeoffs work out to be about the same. The details of the projectile matter a heck of a lot though.

Re:Smaller projectiles?

[suutar]

The energy would have to change. All the kinetic energy the projectile has when it leaves the muzzle is energy it got from the magnetic fields, which came from the batteries. Since the length of the barrel is a fixed design requirement, 5x velocity means 5x acceleration, which means stronger magnetic fields, which means more battery power.

You have a point about the powerup/powerdown, he's not as concerned with the leading edges of the transitions as the trailing edges, and starting the transition earlier could be sufficient to keep the end of the transition at the right time. But the increased power levels for the stronger fields also increases the transition time, and it may be that the transition time for the coils he's using gets to be too long to be manageable, so we may still need more and smaller coils.

3% velocity

[girlintraining]

okay, a .22 averages around 1,120 f/s. 3% of that is 33.6 feet per second. That translates to around 23 MPH. Yes, I can see how this highly dangerous weapon might add to the controversy of 3D printed guns. It is only slightly slower than an olympic sprinter running at full tilt.

Re:3% velocity

[h4rr4r]

Terrifying, this flings nails not quite as fast as a young child could through them.

Re:3% velocity

[ModernGeek]

I want to know what's been keeping someone from building a beefier, actually deadly version of these.

Re:3% velocity

[Type44Q]

It is only slightly slower than an olympic sprinter running at full tilt

I don't have to outrun you, I just have to outrun your bullets...

Re:3% velocity

[WiseWeasel]

The article mentions an actual speed of 40m/s, which converts to 144km/h or around 90 MPH. Still not setting any records, but the video does indicate these things can do some damage.

Re:3% velocity

[TheCarp]

Yup. Actually I was recently interested in coil guns and using my 3d printer to turn out some ideas I was having. It was fun but, I never actually even got to a working prototype. I did however do some reading up on what others have done and.... its a mixture of impressive and not so much.

This site http://www.coilgun.ru/ attempts to track and showcase where hobbiests have gotten on coil guns. Only a handful of them are at the point that I would consider them even passable weapons. Most are, at best, minor annoyances on the level of "you will put an eye out". Maybe some could kill/injure someone with a point blank shot directly to the eye socket, or a very "lucky" hit.

The most impressive I saw fired with an SCR and used a second SCR dampening circuit to shut down the original SCR.

~30 m/s seems to be about the best most designs have been able to hit, with many being far less than that, and only a few making it into the 45-50 m/s range. Even those top end seem to get only around 5-6 Joules of kinetic energy.

Re:3% velocity

[Desler]

The article is wrong. Even the fastest 22 bullet has a velocity of 1640 feet/sec or 500 m/sec. 3% of 500 is only 15 m/sec or around 33 mph.

Re:3% velocity

[girlintraining]

Probably just that this is a friggen PROTOTYPE (FTS), indicating that they WILL build a deadly version of this. Shit, who the fuck doesn't understand how "progress" works?

I'm pretty sure our first ICBM prototype wasn't a water-pump model with a warhead on the top of it. The mature versions of this technology are typically ship- or airplane-mounted, and require huge amounts of energy. Simply put, there won't be a personal-use version of this technology until a revolution in battery technology happens. The energy densities are several orders of magnitude too low right now.

Bottom line here is it's a nice science project for bored electrical engineers. But that's it. It's the EE's version of your 3rd grade "volcano"... pour in some baking soda, vinegar, and food coloring, and hope you get a passing grade.

Re:3% velocity

[Desler]

So either the 3% figure is wrong or the 40m/s figure is wrong.

Re:3% velocity

[girlintraining]

Eh, small point of reference. A coil gun and a gauss gun are two different things. A coil gun works by pulling the slug magnetically down the barrel. A gauss gun works by putting the slug on rails and running a charge across it. But neither are going to be particularly dangerous with the amount of electricity available to your average home owner. -_-

Re:3% velocity

[Trailer Trash]

If you RTFA, you'll find that the muzzle energy is 3% of that of a .22, not the velocity. The velocity is about 40m/s, or about 90MPH.

Re:3% velocity

[h4rr4r]

Physics?

You need a ridiculous amount of current, you need coils with a near instant rise time and you need switches that flip instantly. Good luck.

Re:3% velocity

[TheCarp]

Interesting, I always thought a gauss gun was a coil gun, and what you are describing is a rail gun.

Since gauss is a measure of magnetic field strength, and both of them use magnetic fields to propel the projectile (albeit through different mechanisms, since one is a passive projectile and the other is actually an odd form of single loop coil that has an unusually low resistance to deformation in one direction) it would make sense to me to call both gauss guns, and use coil/rail to differentiate the types.

Re:3% velocity

[girlintraining]

Eh.... my bad. I haven't had my morning coffee yet... whrrrggrrrble.

Re:3% velocity

[bmk67]

Precisely!!!11! Won't you think of the nail-flinging children?

Re:3% velocity

[Antipater]

No, a coilgun and a gauss gun are the same thing. "Putting the slug on rails and running a charge across it" is a railgun.

Re:3% velocity

[Ardyvee]

Neither, considering that the article mentions 3% muzzle energy of an .22 LR which is different than the muzzle velocity. Proof: this picture here

Re:3% velocity

[Antipater]

In other news, I post too slowly.

Re:3% velocity

[internerdj]

As if the internet didn't have enough ways to go blind.

Re:3% velocity

[XxtraLarGe]

It is only slightly slower than an olympic sprinter running at full tilt.

I still wouldn't want to get shot with it.

Re:3% velocity

[Izuzan]

the Designer claims it fires the nails at 9000 Feet Per Second. i asked him to verify that as a 556 nato round is only going 3500 FPS at most. and firing a 556 in a room like that would be dangerous with a steel projectile as it would ricochet around the room.

Re:3% velocity

[pruss]

The muzzle velocity is 40 m/s according to the article, i.e., 131 ft/sec or 89 mi/h. I wouldn't want to be hit with that.

The 3% figure refers to the kinetic energy, and perhaps reflects a less massive projectile than the .22 shoots.

Re:3% velocity

[h4rr4r]

You can tell from the video that is not possible.
1. They would go right through the laptop and the rest of the building.
2. They would have made a sonic boom/crack, like even the lowly .22 does.
3. What magic power source would do that?
4. What magic coils would power up that quickly?

Re:3% velocity

[H0p313ss]

As usual, the summary is wrong and Slashdotters can't be bothered to read the article.

Re:3% velocity

[serviscope_minor]

Simply put, there won't be a personal-use version of this technology until a revolution in battery technology happens. The energy densities are several orders of magnitude too low right now.

A single chunky but not especially big 5000C lipo battery can dump out about 2 kW for a minute and a half or so before discharging. Astonishingly they are acutally rated for that current. With a 10% conversion efficiency, that would be about equivalent to a 9mm pistol round every few seconds.

Not super impressive, but not terrible either.

The thing is tha autoloader is actually pretty good. That's probably the hardest part.

Scaling up gauss guns is pretty easy since that part is understood. You need bigger, lower inductance capacitors, larger thyristors and more powerful charging hardware.

It does however look like the coilgun part is indeed a bottlerocket equivalent for now.

That said, even bottle rockets can be juiced a bit. I used to send them up with a launch pressure of 50 to 100psi.

Re:3% velocity

[CanHasDIY]

Probably just that this is a friggen PROTOTYPE (FTS), indicating that they WILL build a deadly version of this. Shit, who the fuck doesn't understand how "progress" works?

I'm pretty sure our first ICBM prototype wasn't a water-pump model with a warhead on the top of it.

Apples and oranges - an ICBM is based on long existing and well-vetted technology rocket-based weapons technology; it's more akin to the not-yet-existing "deadly version" mentioned by OP than the prototype. Even the "first ICBM prototype" was based on pretty well known, time tested stuff.

You'd be more accurate if you compared this prototype to, say, Goddard's rockets from the early 20th Century.

Re:3% velocity

[AK Marc]

So, you can't think of a solution, so it must be impossible.

Great logic there.

Super-caps (And undefined marketing term, yes, I know) are getting more common. Someone could grab one of them out of a Mazda 6 (or order the spare part, no, I don't have a parts list with pricing) and charge it up off residential current, and get a few shots (20-30?) out of a charge. That's off-the-shelf technology today.

Re:3% velocity

[bill_mcgonigle]

It is only slightly slower than an olympic sprinter running at full tilt.

I still wouldn't want to get shot with it.

Yeah, if somebody fires Ben Johnson into you at full sprint, you're going to have a bad time.

Re:3% velocity

[bill_mcgonigle]

So apparently the quote is: "over 9000? There's no way that can be right." linkage.

I'd be quite satistifed if I had the engineering skills to build that in my garage. Kudos to the guy for moving past 4chan.

Also: the Dell got what it deserved.

Re:3% velocity

[DerekLyons]

Even so, a sharp projectile hitting your at 23MPH still isn't something to laugh at as the grandparent attempts to do.

Re:3% velocity

[jxander]

I'm actually thinking we need less beef to make it more deadly. Specifically in the ammunition

Kinetic energy is Mass x Velocity-Squared. Velocity (being squared) is the biggest driver. A smaller projectile might pick up more speed and thus improve the overall kinetic energy.

Maybe not... can't really be sure. A smaller object might not pick up as much magnetic pull (is there a saturation point? IANAScientist ... I just play one on TV) Either way, probably worth investigating. And a smaller object would probably have better penetration against soft targets like skin... though it probably wouldn't be as impressive against an LCD screen.

Re:3% velocity

[suutar]

The subject of the comment is wrong. The 3% figure is for muzzle _energy_, not muzzle _velocity_.

Re:3% velocity

[Feyshtey]

Everyone seems to have missed the battery controversy in this article.

Simply put, there won't be a personal-use version of this technology until a revolution in battery technology happens. The energy densities are several orders of magnitude too low right now.

Re:3% velocity

[jxander]

Are you sure he claimed exactly 9000 fps?

Or is the power level OVER NINE THOUSAND!

Re:3% velocity

[XxtraLarGe]

By "it", I was referring to the gun's projectiles, wise guy. :-D

Re:3% velocity

[operagost]

Better to fire Usain Bolt. Then you can tell the ATF that it's a Bolt-action weapon.

Re:3% velocity

[LanMan04]

muzzle energy != velocity

If these filed-down nails weigh a fraction of a .22 bullet (they probably don't, though), they could be moving pretty quickly.

Re:3% velocity

[Cramer]

The "military grade" systems (which have been around since the 90s -- 'tho I'm unaware of them being anywhere but the test ranges at Aberdeen) don't use batteries; they use massive (gold) capacitors. I don't care what sort of battery you have, it will not dump as fast as a capacitor.

Re:3% velocity

[GodfatherofSoul]

Your big brother used to when he was pelting you with them.

Re:3% velocity

[lgw]

Depends what you mean by "22 bullet" - I guess you mean 22 LR? A 220 swift is a "22 bullet" - 5.7 mm diameter - that fires at 3000-4000 fps depending on bullet weight and barrel length.

22 LR is very popular for target shooting because it's so cheap, and because it's about the lightest round (lowest energy and thus recoil) that will still behave like a bullet, not a paintball. While still dangerous, it's not useful for hunting anything much larger than a rabbit, so when you start arguing about what small percentage of 22 LR energy a "gun" has, you're already joking.

Re:3% velocity

[lgw]

You'd be hard pressed to hunt even mice with such a projectile, unless it weighs nearly as much as the mouse. There's a wide range between "could cause a dangerous accident" and "useful as a weapon". Even a rifle firing 22LR is arguably in the former category, though it's fine for hunting sufficiently small game.

Re:3% velocity

[Snowgen]

Even so, a sharp projectile hitting your at 23MPH still isn't something to laugh at as the grandparent attempts to do.

23 MPH is about 10 meters per second. So this is about the same as a nail rolling off the roof and hitting your shoe as you walked by.

I think I could laugh at that.

Re:3% velocity

[savanik]

If you check out their website, the muzzle velocity is 42 m/s, or about 137 ft/s (93 miles per hour). Yes, still much slower than a 22. It's the muzzle energy that's 3% of the .22 LR cartridge, owing to a much lighter projectile. Still well below the muzzle velocity of your average Airsoft rifle - but it clocks in at 10x the muzzle energy of those toys. Really wouldn't wanna get hit with it anywhere I didn't have some kind of protection over.

Re:3% velocity

[sootman]

According to Wikipedia, a BB gun has about 18% of the muzzle energy of a .22. And this thing is 1/6 the strength of that. We're getting down to Lego territory.

Re:3% velocity

[jittles]

You'd be hard pressed to hunt even mice with such a projectile, unless it weighs nearly as much as the mouse. There's a wide range between "could cause a dangerous accident" and "useful as a weapon". Even a rifle firing 22LR is arguably in the former category, though it's fine for hunting sufficiently small game.

You do realize that most civilian firearm deaths occur from a .22LR right? Tried finding the UCR Report data from the FBI but I couldn't find anything in the short time that I have. But there are way more .22LR's floating around than anything else out there, and the ammo is much more affordable.

Re:3% velocity

[serviscope_minor]

Super-caps (And undefined marketing term, yes, I know)

http://en.wikipedia.org/wiki/Supercapacitor

Re:3% velocity

[girlintraining]

Even so, a sharp projectile hitting your at 23MPH still isn't something to laugh at as the grandparent attempts to do.

Grandma here. When I was your age, I used to go putzing around through farm fields stealing corn, riding motorcycles, and other acts of rural mischief... because well, it's the country, and what else are you going to do? Naturally, the farmers, who themselves have done these sorts of things, loaded up the shotgun with bird shot or salt, and blasted away at us.

Yes, I've been shot at with a shotgun. Many times. I've dug the bird shot out of my clothes. Once or twice, squeezed out a few pieces that had managed to get embedded like little splinters in my backside. But let me be the first to tell you... muzzle energy does mean something.

It means that 3% of the kick of a .22 at anything beyond point blank range is unlikely to penetrate even bare skin. A t-shirt is sufficient to keep it from doing anything more than leaving a bruise.

So yeah, it is something to laugh at because I actually know a thing or two about guns, unlike you. Anyone who tried to shoot me with this thing, assuming I wasn't able to kill them where they stood trying to pick up and aim this monstrosity at me, I would be sufficiently protected by simply wearing a thick hoodie... because that's what I wear when going to play paintball with my friends... and those hit at around 200 MPH.

So again. Ha. Ha. Ha. This gun is less dangerous than a tennis ball.

Re:3% velocity

[lgw]

You do realize that "dangerous accidents" are a far higher cause of death than deliberate shootings, right? Many a hunter has been hit by a spent round and died needlessly several days later because he didn't seek emergency care, and eventually died from "minor" internal bleeding.

There was a time when 22s figured prominently in crimes, but then Dirty Harry came out, and suddenly most crime-related gun injuries were from far more deadly weapons (seriously, the statistical shift starting in 1971 is marked).
 

Re:3% velocity

[chihowa]

If an average .22 muzzle energy is 200 J, then 3% of that is 6 J. The muzzle velocity is 40 m/s, so the mass of the projectile is 3.75 g. Or almost twice the mass as an average .22 bullet. Remember that the velocity contributes more to the kinetic energy than does the mass.

Wikipedia lists several .22 lr bullet velocities and energies, and I picked a roundish number in the middle. For reference, (among others) it lists a 2 g bullet traveling 440 m/s with an energy of 191 J.

Re:3% velocity

[Thanshin]

It is only slightly slower than an olympic sprinter running at full tilt

Now, to complete that analogy, we only need:
- The mass of an Olympic sprinter.
- The volume of the nail.
- The half-life of the heaviest magnetic material to calculate it's density by the time it reaches the target.

Re:3% velocity

[girlintraining]

So, you can't think of a solution, so it must be impossible.

Yeah, the laws of physics oppress me too. Specifically, E*sqrt(K) = .5(mv^2). When you consider how much energy you lose by pumping some several hundred amps into wire the thickness of a human hair, let's just say inductive reactance is going to fuck you long and hard... to even manage to push out a paltry 130J of muzzle velocity, you're going to need to convert about a car battery's worth of energy instantly into electromotive force. Now, assuming you manage to successfully do this... the coils are going to explosively vaporize from pumping a few mega-joules into them.

You will not get "a few shots" off at the energy level a .22 puts out. You will get a shot off. One. And then your gun will be a smouldering ozone-smelling pile of metal ooze from inductive heating.

Physics: Because fuck you.

Re:3% velocity

[AK Marc]

Yeah, the laws of physics oppress me too. Specifically, E*sqrt(K) = .5(mv^2) [wikipedia.org]. When you consider how much energy you lose by pumping some several hundred amps into wire the thickness of a human hair, let's just say inductive reactance is going to fuck you long and hard...

Again, you worked hard to do it wrong then claim it's impossible. Why not use a better wire? Oh yeah, we want to do it wrong and complain how it doesn't work when we deliberately sabotage it.

to even manage to push out a paltry 130J of muzzle velocity, you're going to need to convert about a car battery's worth of energy instantly into electromotive force.

The capacitor I mentioned can do that and more. It's here now, and can be done, even if you prefer to whine about it and post incompetent engineering and anti-science to prove your point, which is the opposite of reality.

Re:3% velocity

[delt0r]

Google it. There are some. Note that coil guns have limited velocity and power. Rails are easier to get deadly with a power source that can handle the current. Linear motors are between both. Also i would not want you firing this thing at me. You could take out an eye!

Re:3% velocity

[wagnerrp]

The article actually mentions 40m/s, or 3% of muzzle energy, not muzzle velocity. Remember, energy increases with the square of velocity. That comes out to 750fps, which would indicate the builder fires bolts roughly 50% heavier than a typical .22LR round.

3D printing controversy?

[Feyshtey]

Saying that this contributes to the "3-D printed gun/rifle controversy" is a falacy. This weapon has limited components associated with 3D printing. The majority of the device appears to be machined aluminum. Not to mention the large about of electronics and power technology incorporated in the design. This has about as much to do with the "3-D printed gun/rifle controversy" as it does the "electrical engineering controversy".

Re:3D printing controversy?

[pherthyl]

>> This one manages to unleash a metal slug at a speed you can literally out run if you're in shape. I can throw a baseball faster than this thing, and it'll cause more damage too.

Wow, you can run at 140km/h? Why don't you compete in the olympics?

Re:3D printing controversy?

[csumpi]

Saying that this contributes to the "3-D printed gun/rifle controversy" is a falacy.

Sure, but it ups the page views. Welcome to the new /.

Re:3D printing controversy?

[Feyshtey]

There's no controversy anyway. There are plenty of ways one can create a gun that dont involve 3D printing. The only thing that uneducated people point at to "prove" that this is a controversy is the lack of skill required to 3D print a firearm. That also is a fallacy. Aside from the fact that there arent current materials that make it a viable means to create a weapon, and you must still be able to hone, clean, and assemble firearms in a manner that avoids blowing your own face off when you fire the thing, you can still build a very effective weapon if you can run a drill and screw steel pipes together.

The means to make a weapon is irrelevant. You can make nasty shit with what's under your kitchen sink but you dont hear about a crusade against cleaning products. The only reason that this "controversy" has gained any traction are the shear volume of people with equal ignorance of both 3D printing and firearms.

Re:3D printing controversy?

[bill_mcgonigle]

The hand grip is black plastic, thus it scares me (and could have been 3d printed, except it's cheaper to buy a nicer one).

Re:3D printing controversy?

[jxander]

Fires at ~90 MPH. Unlikely to outrun. Also unlikely to be lethal, but c'est la vie. Just a prototype.

Probably less damage than baseball (same speed, less mass). Potential for more damage though, on penetration. Is there an official damage conversion chart : Piercing vs Bludgeoning? D&D maybe.

Either way, piercing unlikely. No rifle-spin to maintain trajectory. Still would rather not get shot with.

Re:3D printing controversy?

[girlintraining]

Fires at ~90 MPH. Unlikely to outrun. Also unlikely to be lethal, but c'est la vie. Just a prototype.

Paintball gun: Fires at 200 MPH. Tickles if you get hit while wearing a hoodie. Definately non-lethal, but c'est la vie. Not a prototype, over twice the speed, runs on canned air.

Threat level: Minimal.

Re:3D printing controversy?

[jxander]

Neither can compete with black powder yet. One might, eventually

Currently, rail gun can't even compete with NAIL gun. (yes, technically Gauss != rail gun, but it RHYMES!)

Nail Gun ballistics

Re:3D printing controversy?

[jxander]

Just because something isn't like to pierce or be lethal ... that doesn't make it a fun time. I'd rather not just punched in the chest, which is even less likely to pierce skin.

And yet ...

[gstoddart]

Oh, sure, they can make this, but I still can't find a stapler which will go through more than about 10 pages without resorting to the big monster next to the printer. ;-)

Re:And yet ...

[operagost]

That's because you're using the Bostitch. I use a Swingline, with Swingline staples to ensure compatibility.

Re:And yet ...

[Zynder]

Well he probably has the same problem I do- someone took his Swingline. The red ones are particularly known to just up and walk away.

NFA?

[i.r.id10t]

Lets hope he's got all his tax documents in line with the BATFE ....

Re:NFA?

[bmk67]

Why? It's not a firearm, and therefore does not fall under NFA.

Re:NFA?

[OverlordQ]

Yes it is.

For the purposes of the National Firearms Act the term Machinegun means:

        Any weapon which shoots, is designed to shoot, or can be readily restored to shoot, automatically more than one shot without manual reloading, by a single function of the trigger
        The frame or receiver of any such weapon
        Any part designed and intended solely and exclusively or combination of parts designed and intended for use in converting a weapon into a machinegun, or
        Any combination of parts from which a machinegun can be assembled if such parts are in the possession or under the control of a person."

This clearly falls under the the first point.

Re:NFA?

[Anonymous Coward]

The NFA only applies to *FIREARMS*.

This does not meet the definition of a *FIREARM*

You are quoting the definition of a *MACHINE GUN*, not a *FIREARM*. *MACHINE GUNS* are strictly a subset of the set *FIREARMS*.

Re:NFA?

[bmk67]

No. It is not. The NFA covers firearms, not weapons which are not firearms.

Please, contact the ATF and inquire about a NFA stamp for a full-auto air gun and see what they say. Or a gauss gun, for that matter.

Re:NFA?

[EmperorArthur]

Yes it is.

For the purposes of the National Firearms Act the term Machinegun means:

        Any weapon which shoots, is designed to shoot, or can be readily restored to shoot, automatically more than one shot without manual reloading, by a single function of the trigger

        The frame or receiver of any such weapon

        Any part designed and intended solely and exclusively or combination of parts designed and intended for use in converting a weapon into a machinegun, or

        Any combination of parts from which a machinegun can be assembled if such parts are in the possession or under the control of a person."

This clearly falls under the the first point.

Ehh, who needs mod points.

By that definition, then nerf and airsoft machine guns are illegal. Clearly you're missing something. Either that, or the US laws really are that bad, and the only reason why everyone is not in jail is because of selective enforcement.

For those who don't realize it, selective enforcement means the government and police can throw anyone they dislike in jail. It's a major enabler of tyranny.

Re:NFA?

[h4rr4r]

Or the big thing you missed is that this is not a Firearm and as such the NFA does not apply.

Re:NFA?

[AK Marc]

Holly Shit!. I bought a rubber-band gun 20 years ago that was a Machinegun!. 6 rubber bands in a single pull of the trigger. And no tax stamp.

Do remember how fast 3% of the muzzle velocity is

[ThatTreeOverThere]

I hope you guys do notice that this is slower than the average CO2 pellet rifle... if it fires at 40 feet per second or so, why wouldn't I just buy a normal BB gun or something? I could more easily just grab a 540 fps .22 air rifle for maybe $60 right off the shelf of a Dick's Sporting Goods. And what in hell does this have to do with 3D Printing??

Would toenails work?

[G3ckoG33k]

My neighbor's kid brother used to spit them at us while watching tv when he was a kid. I just wish I had had some chemical propellant to blast him off.

Re:Do remember how fast 3% of the muzzle velocity

[iggymanz]

even an amateur-made slingshot would be faster

hard to beat gases for pushing projectiles unless you have the nuclear reactor and gen set of a battleship handy

Re:Lots of Power

[CanHasDIY]

This kind of gauss weapon is not new. The big limitation is power.

If you're the U.S. Navy, with a nuclear power plant aboard your aircraft carrier, a railgun is easy to power:
http://www.military.com/features/0,15240,160195,00.html

A rifle? Catch Doc Brown next time he stops over in 2013. Maybe he has an extra Mr. Fusion to spare.
If you throw that in a backpack, maybe you can power your handheld rifle for a few shots.

Couldn't BFC's (Big Fucking Capacitors) be used to store charges? Like the kind you would get from a car stereo dealer?

Can anyone explain why they would/wouldn't work? I'm fairly newbish when it comes to the intricacies of electronics, and trying my best to develop a healthy understanding.

Re:Do remember how fast 3% of the muzzle velocity

[Pinhedd]

The post claims about 40 m/s which seems pretty reasonable given the video footage, that's about 120 feet per second.

Re:Summary incorrect - not 3% muzzle velocity

[brit74]

Yeah, I verified that the comment exists, but I'm certain that it's wrong. Based on the damage he does to the cans and the laptop computer, there's no way his bullets are travelling at 6000+ MPH.

It highlights some of the legal issues

[bugnuts]

In the US, it is legal to make a gun. A real gun that fires real bullets (one at a time).
But it is illegal to sell it, unless you're a firearms manufacturer.

Most people don't realize this, and is the heart of the 3D printed gun "controversy". The only reason it's a controversy is that most people don't know this. The ATF isn't very concerned, because the 3D printed guns will not really change the amount of guns in circulation... they're a one-off and will not last for generations, unlike a real gun.

I don't believe a gauss gun qualifies as a firearm. Thus, the laws against fully-automatic firearms (or firearms at all) don't apply, and is more akin to a BB gun, paint pellet, or airsoft gun. But this gauss gun has the potential of actually firing lethal rounds because it's not limited to the speed of expanding gases, which I find interesting.

Re:It highlights some of the legal issues

[h4rr4r]

Actually it is totally legal to sell the gun, so long as that was not the reason you built it. So if you build a gun, and get sick of it a few months later you can legally sell it. This may not be legal in your state though, I am speaking only about federal law.

This gas gun does not have the potential of firing lethal rounds. The speed of expanding gasses is a heck of alot faster than this thing will ever propel a projectile.

Re:It highlights some of the legal issues

[g0bshiTe]

I think the 3d-printed statement was more to draw attention to the fact that there's more ways than just printing guns to make them and that alternate methods exist.

Re:It highlights some of the legal issues

[Creepy]

Not that that type of gun couldn't be lethal - I've seen a man portable rail gun (similar to a gauss gun, but uses different forces) built in a (high school) classroom in AP (accelerated physics) for a group final project propel a nail through several cinder blocks. It did about as well as a 9mm handgun, if I recall correctly, though it was much heavier and fired much slower (like maybe 3-4 nails per minute max).

And no, they obviously didn't test shoot it at school, at least not with anything in it. All shooting was on a firing range and captured on a high speed camera (1000FPS) the physics department owned (thanks to concession stand sales). They also shot footage of several other guns (owned by people at the range, I believe, but at least one of them was 18 at the time, so it is possible he owned or obtained them for this purpose) shooting cinder blocks to compare speed and penetrating power compared to their rail gun. They mainly used different sized nails for railgun ammo, though they did try a thumbtack (and it failed spectacularly - too soft, too fluttery)

Re:It highlights some of the legal issues

[delt0r]

The controversy is in fact much simpler. "Gangsters can make their own guns!" is scary. Replace Gangster with whatever your moms current boogie man is and that is the controversy.

Never mind the fact that these people have all the guns they want anyway...

Re:It highlights some of the legal issues

[wagnerrp]

It's a function of energy density. A 9mm handgun has far more energy behind it, but is blunt. The nail was a flachette, basically an armor piercing projectile. It penetrated a whole lot deeper, but it didn't carry much energy in comparison to its penetrating capability.

Are you sure they built a railgun rather than a gauss gun? Railguns require the projectile to be conductive and slide along the rails to complete the circuit. You could only use nails in a railgun if you either snipped off their heads first, or wrapped the shaft in a sabot to stabilize it down the barrel.

Re: It highlights some of the legal issues

[wagnerrp]

Railguns are merely propelled by plasma instead of contained expanding gasses.

That really depends on how high you run your amperage, and is not an inherent requirement of a railgun.

Re:Summary incorrect - not 3% muzzle velocity

[h4rr4r]

9000 fps cannot be right.
That would make this thing supersonic.

At 9000fps these nails would go through the back of his garage, not be stopped by a laptop screen.

Re:Summary incorrect - not 3% muzzle velocity

[oodaloop]

Ah, yes. Youtube comments. The ultimate source of unbiased truth. And so wise.

Re:hi

[dgatwood]

Yeah, this is the first G+ post I've seen, and it's spam. Not a very promising start.

Re:Summary incorrect - not 3% muzzle velocity

[h4rr4r]

Have you collected all the dragon balls?

I don't care who you are

[g0bshiTe]

That's bad ass!

Re:Do remember how fast 3% of the muzzle velocity

[csumpi]

this is slower than the average CO2 pellet rifle

Yeah, but the bullets are much bigger. So this would hurt a lot more than a pellet.

And what in hell does this have to do with 3D Printing??

Nothing. But adding that increases the page views. This is how timothy's gonna buy that Ferrari.

Post is ignorant

[Groo Wanderer]

The big problem with this post is that it misses the entire point of the problem. You can make Gauss guns with ease, they work, and they fire things at high enough velocities to destroy hardened armored targets. That is not a challenge, the problem is making them last more than a few shots before they self-destruct.

This story was all about a low velocity gun that can fire more than 10 bolts at low speed. Again not a big deal. The problem is that they are using low power (relatively) to do this and it lasts a "long" time. When you up the power to useful level, it rips the rails us, oxidizes/burns them, warps them from heat, and all the other problems that are real engineers are struggling with.

In essence the OP says that they can avoid all the consequences by avoiding the useful effects of the device. Great, how can this not be considered a step forward! I can make a 500MPG car that doesn't actually move very fast and isn't large enough to carry a can of beer much less a person, is that too a massive advance in tech? Idiots.

Re:Post is ignorant

[samwichse]

No where does it say this is a massive advance in tech. It is described as "interesting."

What it is is a massively cool bit of home engineering.

Oh, and it's a gauss (coil) gun, not a rail gun. Gauss guns don't have the same issue of disintegrating rails.

Chill,
Sam

Why?

[1s44c]

Why do this? You could make anything with a 3D printer, what does it say about you that you only want to make weapons?

How about making a computer case? A motorbike? A fembot?

Re:Why?

[wonkey_monkey]

Why do this? You could make anything with a 3D printer, what does it say about you that you only want to make weapons?

Weapons are fun ("science fiction" weapons doubly so), and actually can be enjoyed without turning the user into a homicidal maniac.

Re:Why?

[CanHasDIY]

Why do this? You could make anything with a 3D printer, what does it say about you that you only want to make weapons?

How about making a computer case? A motorbike? A fembot?

TL;DR, huh?

Didn't even bother with the summary...

Re:Why?

[1s44c]

It's hardly self righteous to ask why people want to make things to kill when they could make anything at all.

Where are the stories about people making go-carts or a mini-helicopters with 3D printers? Are quadcopters not cool anymore?

You're ignorant

[ShooterNeo]

The drawbacks you mention apply to rail guns, not Gaus guns. Gaus guns have serious problems of their own (most of the prototype designs aren't powerful enough, the only design I've read about that would probably have truly useful velocities requires superconducting magnets. If you read the wiki article, apparently there's serious problems with iron projectiles.)

http://en.wikipedia.org/wiki/Coilgun

http://en.wikipedia.org/wiki/Railgun

http://www.askmar.com/Massdrivers/Superconducting%20Quenchgun.pdf

On Page 6 it has an interesting table of the actual mass and physical dimensions of the accelerator. Note that muzzle energies far greater than proposed for the Navy's railgun project are possible (the smallest one is 1820 megajoule's, the navy wants a 64 megajoule railgun) but also notice the huge size and bulk of the launcher : 147 meters long.

But there's no arcing problem, and the proposed design is supposed to be reusable.

Re:You're ignorant

[ShooterNeo]

That's fine, but consider the relative mass ratios of human crew mass to space station mass. The ISS weighs 419,455 kilograms, while it only has maybe 300 kilograms of crewmembers onboard. That means that more than 99.9% of the mass is things that might be able to withstand the acceleration you mentioned.

Now, of course this is optimistic, none of the ISS's assembled modules can withstand 360G of acceleration. But all kinds of raw materials, basic components, supplies, and so forth can. If we had a big quenchgun launcher we could probably send at least 90% of the stuff needed in space as disassembled components that can survive the Gs.

Re:The big design problem here...

[wonkey_monkey]

Just a series of nudges, which may well SLOW the bolts for half the time.

Why would it slow it down? The infrared detectors turn the coils off once the projectile gets to the centre, then the next coil turns on. What would cause the projectile to slow down?

This may be a stupid question, but...

[wonkey_monkey]

Bullets are made from turned-down nails

What's a "turned-down nail"?

Not thinking big enough

[SuperKendall]

Correct me if I'm wrong

Ok, you're 100% wrong.

A Gauss gun involves no explodes, or cartridges. The projectile is propelled only by magnetic force.

This is exactly why people should play Car Wars at some point, to understand better all varieties of weaponry possible.

Re:Lots of Power

[smellsofbikes]

This kind of gauss weapon is not new. The big limitation is power.

If you're the U.S. Navy, with a nuclear power plant aboard your aircraft carrier, a railgun is easy to power:
http://www.military.com/features/0,15240,160195,00.html

A rifle? Catch Doc Brown next time he stops over in 2013. Maybe he has an extra Mr. Fusion to spare.
If you throw that in a backpack, maybe you can power your handheld rifle for a few shots.

Couldn't BFC's (Big Fucking Capacitors) be used to store charges? Like the kind you would get from a car stereo dealer?

Can anyone explain why they would/wouldn't work? I'm fairly newbish when it comes to the intricacies of electronics, and trying my best to develop a healthy understanding.

A non-inclusive answer is that the energy stored in a capacitor rises with the square of the voltage, so what you want for really high energy density is very high voltage caps. But, along with that, when you discharge them, you're relying on an extremely quick discharge so you get huge amounts of amperage out of them (discharge current = voltage / time) so you also need massive current-carrying capability for the plates and wiring. That means fairly specialized capacitors.

Re:Lots of Power

[DMUTPeregrine]

There are two issues, energy storage and coil quality. Capacitors aren't good for long-term energy storage due to dielectric leakage. The work coils have to be good (and the barrel strong) to prevent them from self-destructing due to the forces imparted by firing.

Re:The big design problem here...

[Amouth]

I wonder why my original comment got no points, but your query got two?

Because rather than adding to the conversation, maybe by stating your statement and giving an example of how to fine tune it, you just come in here and try to crap on something someone did without giving any constructive feedback.

Example being i could have just responded "because you're being an ass" but rather i'm giving you feedback that instead of just "being an ass" you could give some insight on not just what you think is wrong but what could be done to improve it.

(yes i know this is an AC, but obviously this one likes to read his words, maybe he can take some constructive criticism and change for the better, well lets hope)

Re:Lots of Power

[CanHasDIY]

This kind of gauss weapon is not new. The big limitation is power.

If you're the U.S. Navy, with a nuclear power plant aboard your aircraft carrier, a railgun is easy to power:
http://www.military.com/features/0,15240,160195,00.html

A rifle? Catch Doc Brown next time he stops over in 2013. Maybe he has an extra Mr. Fusion to spare.
If you throw that in a backpack, maybe you can power your handheld rifle for a few shots.

Couldn't BFC's (Big Fucking Capacitors) be used to store charges? Like the kind you would get from a car stereo dealer?

Can anyone explain why they would/wouldn't work? I'm fairly newbish when it comes to the intricacies of electronics, and trying my best to develop a healthy understanding.

A non-inclusive answer is that the energy stored in a capacitor rises with the square of the voltage, so what you want for really high energy density is very high voltage caps. But, along with that, when you discharge them, you're relying on an extremely quick discharge so you get huge amounts of amperage out of them (discharge current = voltage / time) so you also need massive current-carrying capability for the plates and wiring. That means fairly specialized capacitors.

So, basically what you're saying is that it's possible, but difficult and costly at our current level of technological achievement?

What sort of figures should I be looking for here? Like, in this chart, what are the relevant columns? I'm guessing "Rated Voltage" and "Energy." Oh, and of course the "Cap" listing.

Thanks for the info thus far, BTW.

I think they meant "trimmed down"

[Radical Moderate]

The heads have been chopped off, so you have a cylinder with a point on one end. Yay slashdot editors.

Re:I think they meant "trimmed down"

[drcheap]

No, it meansturned down.

Turned is a term used in machining, referring to the "turning" action of a Lathe

Re:hi

[XcepticZP]

Just report her profile, Google will ban it eventually.

Wives

[arthurpaliden]

Walking behind me as I watched the video and all she said was "No.".

And it usually ends about here

[pbjones]

Many people get this far with Gauss gun, then the exponential power requirements kick in and you see why only big companies continue development. The theory is good, but it's Hollywood science when it comed down to physical size.

Re:Lots of Power

[rcw-home]

That current-carrying capacity will manifest as an extremely low ESR (equivalent series resistance). For this application, CanHasDIY would want to ignore any parts that don't spec that.

Oh yay

[musth]

Technology making guns more prevalent. Slashdot editors' enthusiasm for this is noted, once again.

As a tool, this might work out

[Animats]

As a weapon, this thing is overly complex. As a tool, it has potential. Nail guns for construction have to accelerate a nail. This is hard to do electrically. Most nail guns require a hose to an external air compressor. This is a drag, especially if you're on a ladder or roof.

There are "cordless" nail guns. Some use a small propane cylinder for power. (Use only in well ventilated area.) There's a DeWalt unit which uses a battery to spin up a flywheel to get enough power to fire a nail. (Heavy, and has trouble driving a nail into hardwood.) The "cordless" technologies are mostly for small finishing nail jobs.

A magnetic drive nail gun could be a useful alternative, if you could get the weight down below the existing alternatives.

Design Quibbles

[EdgePenguin]

The coils turn on by reacting to the presence of the bolt. If the gun is constructed well enough, why can't a simple dumb timer be enough? Sensors seem overcomplicated

The ammunition looks fair large and heavy. Why not try using a smaller nail and getting higher muzzle velocities?

Re:Design Quibbles

[wonkey_monkey]

The coils turn on by reacting to the presence of the bolt. If the gun is constructed well enough, why can't a simple dumb timer be enough? Sensors seem overcomplicated

What if your bolts aren't very consistent in mass or composition? Or you want to make alterations to the power output?

Re:hi

[TheRaven64]

It's very helpful that Slashdot has put little coloured Facebook / Twitter / G+ icons next to spammers. It makes it much easier to ignore their posts...

Re:The big design problem here...

[wonkey_monkey]

Well, Amouth said it best. You don't even know there is a design problem. You've just assumed that this guy hasn't tuned the timing properly so that you can sneer down your nose at him from your lofty position as Expert On Everything. Feel good?

I wonder why my original comment got no points, but your query got two?

My karma is Excellent so I start at 2, and you're unlikely to go up.

Re:hi

[sapped]

How do you report her? I can't find an obvious link back to the actual person that made this comment.

Re:hi

[XcepticZP]

Click on her name, and go to her Slashdot profile. Then in the top right next to her Slashdot ID, you'll see the same G+ icon. Clicking on it will take you to the Google+ profile.

Re:Lots of Power

[smellsofbikes]

Sorry about the delay in replying. Those are some pretty awesome caps for railgun/coilgun/quartershrinker applications. High voltage, high amperage capability. If you decide to play with this, bolt a 1 meg resistor across the cap leads and leave it there all the time that they're not actually installed in working equipment, because this stuff could kill you with a discharge. So, yeah, rated voltage and, if they list it, equivalent series resistance, which is a measure of how quickly it can discharge, and you'd like as small as possible.