Defense Distributed Demos New 3D Printed Lowers


December 26, 2012, 02:03 AM
DefDist has demonstrated some new, redesigned and reinforced AR lowers for 3D printers.

Their previous attempt resulted in a lower that failed after 6 rounds of 5.7mm.

Their new ones failed after about 80 rounds of full-power .223.

More info plus video here:

They're planning to go through further rounds of revisions before releasing the STL files into the wild.

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December 26, 2012, 12:26 PM
Interesting. I wonder if there is a way to print over a spring steel skeleton to create something that is actually strong enough to survive use.

December 26, 2012, 09:00 PM
I expect that would kind of defeat the purpose of what DD is going for, since their stated goal is to release something that anyone can download and print.

I think it's more a matter of designing a lower that works with the materials most commonly used in 3d printers.

After all, there have been a couple of different companies who've made polymer lowers in the past, so I would expect it would just be a matter of tweaking and reinforcing the parts of the design that would be weakest.

I'd really like to see a layman's breakdown of the materials most often used in 3d printers, and whether they could be expected to stand up to long-term use.

December 26, 2012, 09:15 PM
do it yourself is coming to a whole new level.

December 26, 2012, 10:31 PM
The problem with that line of thought is that the common polymer used in the 3D printers is woefully inadequate for use in a high stress part without a huge amount of reinforcement. The polymer lowers that have been on the market were made from better polymers than used for 3D printing for the application and they still were junk. Without some type of composite structure the design will probably end up 3-4x the size of a normal lower, heavier and on the whole more expensive.

December 26, 2012, 11:03 PM
"Makerbot" grade 3D printers use a thermoplastic (ABS is what my friend who has one said he uses if I recall correctly) that not only is not strong enough for even moderate stress, won't stand up to the heat generated from rapid fire.

December 27, 2012, 05:51 AM
I am a Sr. Cadd designer for a medical implant co. I make lots of rapid prototypes (3d printer). Done it now over 10 years and thousands of parts. I would not trust any 3d printed AR for more than a few rounds. If you thicken the high stress areas, they would make good emgency guns.

Metal or fiber suspended liquid using a high end STL machine would be better, but the machines cost more than i make in a few years and the liquid is almost as expensive.

January 17, 2013, 02:35 PM
As failures and stress on the lower go:
Howsabout using a 3D printed lower with a gas piston style AR upper? Where the bolt "return spring" is in the upper itself and not the lower rcvr extension? This would also help reduce some of the heat transfer (if there is much) from the upper to the lower.

Or am I ignorant on the gas piston mechanics? I thought at least some of the designs had no AR 15 style buffer/spring in the receiver extension.

January 18, 2013, 04:44 PM
It would probably make a pretty good .22 lower, especially if we get this "universal background check" BS and you want to have a rifle without asking the government's permission.

Even with the sub-par material, I'm hoping they come up with a version that is reinforced enough to stand up to 5.56. Even if it ends up looking really clunky and goofy (a la High Point pistols), the main cool factor is obviously in the fact that anyone with the printer can make their own with minimal effort.

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