How close are we to effectively making 3d printed lowers? Can

If you adapt the AR-15 lower design to being 3d printed, that is to say make it T H I C C af with a thumbhole stock, i'd say it works just fine.

>>34168330

I see them on armlist all the time. buddie has one, shit shot over 1k rounds with no problem. so pretty damn close.

>>34168579
literally no your buddy doesnt

>>34168330

If you make them right then they could be made today, but people try to copy the lowers exactly instead of adapting them for plastic.

File: poly lower.jpg (76KB, 1024x768px) Image search: [Google]

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i've been looking at this shit for a while now. polymer lowers in general have been failing at the rear of the receiver at the buffer tube.

http://blog.cheaperthandirt.com/polymer-good-idea/

there's a way you can make 3d filament stronger by heat treating it (duh) but it typically shrinks it (also duh). it'd be pretty stupid if you spent a shit ton of time and filament printing out a lower and then it won't be able to fit a parts kit after you treated it.

https://www.youtube.com/watch?v=CZX8eHC7fws

i wouldn't fuck with it unless you needed a lower to test upper builds or just wanted a fancy lower to show off your range toy. i wouldn't use one over an aluminum one atm.

https://www.youtube.com/watch?v=mV1qF7o2NvY

>>34168330
>How closer are we...
A few years ago.

>>34168330
They're reliable enough for most people's shooting in a year. They don't approach the reliability of an aluminum lower, but that's because nothing does, with 5.56 an AR-15 lower will practically run forever.

>>34168964
A thumbhole stock is really a lot better idea than just going with the ordinary ar-15 design.

>>34168964

Another way is to relieve the stress point by making a fixed stock instead of using the M4 style sliding stock.

http://www.gwacsarmory.com/

>>34168964
>>34168330

As the guy with the shovel AK proved, the answer to cheap, untraceable guns is sitting right in front of anyone with even half a clue about sheet metal forming.

Hell, give me the right tools and I bet I could build you nearly a half dozen AK lowers from raw sheet in the time it would take your MakerBot to poop out a shitty, brittle poly AR lower. And I'm just a (unusually mechanically adept) art major who's only experience with metal forming was what I learned about presses, rollers, hammer forming, English wheels, and the like in my sculpture classes. The AK lower is seriously THAT simple.

>>34168578
This.

The specific constraint that 3d printing has over injection molding is that it's strength in one direction is not the same as its strength in perpendicular directions (it's got layers yo)

For an AR lower this comes down to making sure that the stresses your pins place on the assembly are applied in the direction that the part strongest (The bolt catch pin is probably the most problematic, after the obvious stock interface problem)

>>34168964
>polymer lowers
Maybe they should try plastic instead of shellac as their polymer. I also don't recommend DNA or cellulose

>>34169079
There's a bolt-together lower optimized for printing that solves that.

>>34169094
>polymer lowers
>Maybe they should try plastic instead

Thermoplastic polymers are weaker, overall, than thermosetting polymers.

>How close are we to effectively making 3d printed lowers?
Been there for years.

>Can they be reliable?
FDM printed lowers will not be very reliable and should be considered a novelty until some kind of breakthrough arises. It should be fine for a rifle you just take to the range now and then, since the worst that will happen is that it will break and you have to print a new one. Beefed up custom designs, and ones printed in segments and assembled post facto probably help.

Sintered metal is a different beast altogether, but isn't really relevant due to the expense.

>>34169036
>>34169038
yeah i've looked into the cav-15 and they seem to be a pretty good alternative to a standard lower build receiver. but could you imagine the sheer size of your 3d printer when trying to make that thing? i mean the money you spend on that thing could've been put towards a cheap cnc machine to make lowers out of aluminum blanks.

i think (can't remember off the top of my head) the cav-15 is pressure molded. and i haven't heard of a lot of issues with the lower itself. other than being a bit pricey though. i found out about it when i read up on an article about a super light ar build that came in about 4.5 pounds. in the article they stated that if they used polymer they probably could've shed even more weight. that shit be cray.

>>34168330

3D-printing a negative of a lower like the GWACS lower, maybe even + thumb hole, and then using that to produce the actual lower with injection molding from that is probably not even that bad in terms of sturdiness and reliability.

>>34169121

And that's the point really. You can get super light results with it. That's why Ian and Karl are using GWACS lowers for the WWSD builds, they are the lightest option available that's reliable.

>>34169063
yeah, any stamped sheet metal platform would be a better bet than anything. i mean you could easily stamp out a m3 grease gun clone with the proper machines and a little knowledge. i think this whole 3d printing thing is fun for shear fuckery though. kinda like how people drop a big block in a car to make a sleeper.

>>34169183

A lot of it is because "Muh ghost guns!!!" People who want to have unlisted guns for when the government comes to steal them. A lot more is just the desire to have something that you made yourself.

>>34169183
Artfag here, I do get the appeal, I just think people need to think bigger.

I'd love to see someone with a laser sintering printer print out an all-metal G11 or something similar.

>>34169063
>>34169183

A sheet metal AKM receiver still needs a pair of machined trunnions, which aren't exactly off-the-shelf hardware.

Getting a full AKM parts kit and assembling it in a sheet metal taco shell is untraceable in the US at least, but it's hardly cheap these days, like $350 without a barrel (about another $100), and even that is dependent on the availability of 50 year old foreign surplus.

You can do an all new-built AR build a fair bit cheaper.
PSA has lower build kits for $90, and a barreled complete upper receiver with BCG etc. for $250 that isn't PTAC shit.

Also, metal stamping beyond simple cutting and bending is mostly beyond normal homegame shit. It's great for massive production runs, but for a home shop machinist, even vertical milling is much more practical. For one, you need a damn milling machine to cut stamping dies.

You could build a sten gun in a basic workshop, but a grease gun had to be built in a converted auto parts factory.

>>34169079
Honestly might as well leave the bolt hold open out if it proves to be problematic.

>>34169440
I mean, you can make an AR-15 lower out of sheet/plate metal too, if you want.

>>34169109
>A cured thermosetting resin is called a thermoset or a thermosetting plastic/ polymer

>>34172563
>Thermosetting plastic
I have never heard someone call it that.

>>34172618
I have. Basically plastic you can't melt and reform. It's essentially a plastic resin.

>>34172657
But the term "plastic" no longer makes sense if it is cured.

>>34172691
You are confusing thermoplastic with plastic.

>Plastic is a material consisting of any of a wide range of synthetic or semi-synthetic organic compounds that are malleable and can be molded into solid objects. Plastics are typically organic polymers of high molecular mass, but they often contain other substances. They are usually synthetic, most commonly derived from petrochemicals, but many are made from renewable materials such as polylactic acid from corn or cellulosics from cotton linters.[2] Plasticity is the general property of all materials that are able to irreversibly deform without breaking, but this occurs to such a degree with this class of moldable polymers that their name is an emphasis on this ability.