No doubt many of you have read about folks tiinkering with 3D printers to make gun parts.

I've been messing around with the concept for months. As a mechanical engineer, I've been evaluating the "weak points" of what i plastic AR lower might be, and have designed a modified lower to work in ABS.

Take a gander of what I've been developing.

LTS Thor polymer receivers

The parts are rough, due to the level of my 3D printer... A Makerbot Replicator I... resolution isn't great so it takes some sanding, which I wasn't doing.

The ABS material is bomber... very strong, shock resistant, sandable, bondable too.

The full AR in the photos is built up with a DPMS upper, buffer assy, and LPK, Magpul grip and stock. Suppressor shown is fake

First tested with a Ciener .22LR conversion, with FUN results. Then shifted to .223, using 62 grain Remington. Absolutely flawless. And best of all... falls under the 80% rule - as long as you do not sell or give it away, its yours

The best thing is that you can make these yourself!  Wander over to www.grabcad.com, and you'll find tons of AR parts which can be made on a 3D printer. My little Makerbot cost me about $1600, and a few weeks to figure out. Material cost per lower is about $15, but it takes time - about 8 hours per lower to print (I print

the lower as two parts, about 4 hours each to make, then solvent bond the halves together). Then you sand, drill fit the holes, then paint.

I think it is possible to make these polymer lowers as 80% "kits" which can then be sold. The lower would come as pieces, then you'd solvent bond the parts together using some type of alignment jig, do some sanding and fitting, paint, then assemble.

Sure you can buy the other polymer lowers... and of course have to register them... doh!

I think these would make fun kits to build yourself... at least 20% built yourself

The big limitation is the 3D printer. The better the printer, the better the part. "Good" 3D printers, like the Stratasys or Objet printers, can run from $14,000 - $40,000... BUT you can make the lower as one piece... plus its much faster... plus no sanding or drill fitting of holes. A group of guys can pitch in, and you'll be making production quality lowers.

For the folks at the Bureau... "Plastic home made 3D printed lower receivers are for educational or informational purposes only, and not intended for sale or trade..."

Ain't nothin' like an AR that needs no resgistration

I want to know what everyone thinks.

That looks great! No issues with buffer tube?

knock, knock, knock,

Those look really good. I like the front take down pin brace. Looks like more material around the buffer tube as well. What are you using to bond them?

ATF has said the fire control group has to be solid on a 80% lower. With it in two pieces, and without the hammer pin and trigger pin hole drilled, they might give a letter for a paper weight printing vs a firearm manufacturing.

Yep...interesting article in the paper....in a few weeks or so.

LOL... yeah I'm waiting for the agents to show up now...

The nice thing is that the material is ABS - really much easier to machine than 7075 ALU... so the fire control section can be solid...

Did lots of bracing and wall thickening.

The lower starts as two parts that are bonded using ABS pipe cement

With an ABS lower, now you can REALLY do a decent job machining the lower using a Harbor Freight mini mill!

Ahhh, imagine the fun!

No more chewed up 80% paperweights...

If you think about it, it ain't any different than carvin' one out of oak...

hey, theres a cool idea - an oak lower receiver, wood grain and all!

Man the is interesting and very cool.
Need to make some reproductions of early
M16 stocks

I'm picturing an oak lower & upper matched set, with RealTree camo furniture.  It's glorious!

I have read a bit about 3D printers and firearms and that is a pretty cool but scary concept in the wrong person hands..  But that would make a cool 22 dedicated AR.....

Guess what DA?
He can make all of them he wants as long as he does NOT produce them to sell.
As an individual he can make them for himself all day long.

More images (right click icon to open image):









Enjoy, and Happy New Year!

ABSOLUTELY!

The 80/20 rule, meant for flintlock and muzzle loaders, specifies that firearms that are made for the sole use of the maker, NOT for resale, barter or trade of any kind, are legal for ownership.

TADA!

You said it Shadow!!!

The bureau is trying to figure out a way around this, I bet! Imagine what one can make at home, with todays technology???

I really, really want one of these rapid prototype machines.

Its easier than you think Trin... these 3D printers can do things that we used to see on Star Trek... remember the Replicator?

Thats exactly what I use them for... I've used them for ,.223, but would rather use aluminum due to the heat and recoil. Dont get me wrong, there are companies making ABS molded lowers (Plum Crazy is one that comes to mind) but they require registration. But ABS is a proven material for firearm parts.

My lowers don't have a bolt release mount (not needed for .22LR), and the walls are thickened,

I use my lowers as .22 lowers, although I have a couple that I made for .223 use

I started looking into them about a year ago. Back then they were still around $20,000 and up.

There are small companies now making little desktop machines for as low as $1500, but they take a little tweaking, and have some limitations, like low resolution.

Mine is a Makerbot Replicator, which runs about $1700 and runs ABS or PLA.

A perfect high end desktop 3D printer is the Objet Projet 1000, which starts around $14,000, but this little gem will print a PERFECT 1:1 lower receiver, with no sanding or cleanup, perfect tolerances, that looks like an actual production part. I had a sample made from one, and it was a perfect 100% replica of a DPMS lower receiver.

Like I mentioned, if a bunch of guys went in one one, they could pony up the cost of material (a spool of ABS runs about $60 and can make 3-4 lowers) and make lowers all day long. If some of those lowers ended up in the trash, the others might find them and could use them ;)

I would be in for at least two 80% lowers and I know a couple of guys at work who would be interested too. I have been thinking about aluminum 80% lowers but polymer would be much easier to work on.

The AR that is my avatar is an SBR that uses one of my .223 ABS lowers, and it functions great so far, after about 500 rounds through it. Heat isn't an issue since the barrel and upper are the only parts that really warm up, even after sustained semi auto fire through a full mag. I worry a little about the front pin boss, but so far the gussets have helped strengthen the design.

I'd say the weakest link in a polymer lower is the back end where the buffer tube mount transitions into the grip. This is the narrowest part of the lower. In my early samples, this is where the receiver cracked, and that was when the gun was dropped on its stock. My design uses a thicker buffer mount, but it's still ABS. So plastic is not fool-proof (yet), but the technology is getting there. I have made (4) of my new design lowers so far, and each one has worked flawlessly.

One thing to keep in mind - 3D printed plastic parts have layers, like a tree trunk - so the part could possibly crack between layers though I've never seen happen... where a molded plastic part is like one continuous piece of plactic - no layers. So molded parts are typically stronger.

Oh, NOW you're talking!

Imagine a gorgeous tiger maple upper and lower receiver set???

NO need for camo paint... natural WOOD!

I'm waitin' for someone to offer a set!

See, thats my thought... I've done 80% aluminum lowers before, and it was a bitch... ended up having my buddy's machine shop finish them for me.

Will a little tabletop mill, ABS would be a CINCH to machine! And you could use the same 80% jigs and plans too.

I have a CNC mill. Its used mostly for repeated drilling so I don't have a lot of CNC experience but I may try it some day. It uses Mach3 for a program I keep looking for G code already written but have yet to find any. It would be a fun project.

http://youtu.be/YqzJlBcCsow

Tabletop mill? are you kidding me?

Those cost over 1,000 dollars to buy a milling machine.

It would be much much cheaper to just rent a 3D printer for 100-200$ a month.

Get your design plans ahead of time & print about 20+ receivers thru that month.

80% lowers are a bitch to finish and they're costly to finish. buying those stupid mills and drill press and jigs
it would be cheaper to just rent a CNC or 3d printer.

Believe it or not, these 3D printers USE g-code already!

All you need is the 3D model, convert it to an .STL file, and export it into the 3D printer. It converts it to g-code to run the part!

A 80% jig from Tactical Machining, and a polymer 80% lower, and you'be have a full lower in about 30 min worth of time...

My buddy has some CNC Bridgeport mills, so he programmed the work, zeroed the jig, and it took about 20 min per lower to machine.

Thats a great point. Why buy a hokey mill, when you can make a ton of lowers during a months time.

The Stratasys machine I tested only took 3 hours to make a lower, and it was spot on. No finishing work needed.

The milling machine would be ONLY if you were to buy an 80% lower, and had to finish it yourself.

Obviously if you had a 3D printer, you wouldn't need a mill ;)

BUT you could only make them for yourself. Can't give them away or sell them.

Then again, if a person "found one in the garbage can", and another person "found an envelope of money on the sidewalk", it would be fair game!

Not that it would happen - Just sayin'...

If you go to www.grabcad.com, you can find AR lower receiver files already created.
Take the file, convert it to .STL. Then you can download a free program called ReplicatorG (ww.replicat.org), which will take an .STL file and convert it to g-code for you. The caveat is that it is written for 3D printers, so I'm not 100% sure about how it sets up tools, etc, though I assume g-code is just g-code?

So... the next logical step...

Polymer lower frames.

There are files for STI 2011, and Glock frames. I've also heard of files for M&Ps and XD frames too.

Oh, this could get really fun... a home made polymer pistol frame... It is theoretically possible as long as the file exists.

And lets not forget who forged the way for polymer AR gun parts... Magpul.

And of course Glock for pistols.

There are very few of us here who don't have a Magpul polymer stock, grip, or Pmag. These are molded from (mostly) nylon or ABS.

The age of polymer firearms is slowly coming upon us.

I'm not real familiar with 3d printers, but don't some of them print in metal?  Or a sand mold that can be used to make them out of metal?  I don't really have any interest in making my own lowers but it would be nice to see some smaller outfits be able to make them to spec and of good quality to meet demand and bring prices down.  It would be nice to be able to have production ramped up to fill all these orders so I can buy another, maybe a heavy barrel with a good 4-14 scope.

Wow nice work on that lower you created !

why did you cut up that lower? did the other side say spikes tactical on it?

how would testing go -- i mean could others test the lowers for you -- thus you still be the owner but they test it out for you (how ever long it takes to complete a test or too see how long it takes for it to fail)? -- and maybe donating to your cause or research

That "GrabCad.com" has files for .308 ARs also.

Nice

OP, I think you are limiting your design modifications too narrowly.  For instance, why could you not make the grip integral?  Design it to accept Magpul MIAD inserts and then you are not so constrained by the original design's highly stressed area between the grip and the receiver extension hole.

Here's another question: can 3D printers work with thermosetting materials?  I imagine it could be laid down and then baked.  Or use UV reactive material and hit it with a mini-cure between passes.  Or use epoxy and mix the 2 parts immediately before the nozzle, and adjust the feed rate so that by the time the end of a layer is laid down the beginning of the layer is set enough to take another coat.

Damn...now lets learn to print ammo

So... Honest opinions... We have a high resolution 3d printer at my college. Would it be legal for me to submit the 3d file to the school to print if I have to buy the part when it's finished? I mean, what's the difference between buying the materials before or after completion? Thanks.

looks pretty good... Ive been going to print a lower as well... just been to busy. Im going SLS (Glass Filled Nylon) one piece.

I have the model, just never think about throwing it on the  machine. One of these days.

I would keep money so far away from these things you'd think they were made in a commune.  The closest I would come would be to submit the design for an 80% lower - it's been discussed and there's plenty of precedent.

I would also stay away from having them fabricate "halves" or "sections."  Remember that the Cavarms debacle started with the ATF getting their panties in a wad over polymer parts that Cavarms was subcontracting out.  The tech branch had already said that the parts were OK, and then somebody changed their mind.  So I definitely wouldn't submit the 2 halves like the OP built.

Hold the phone - but did I miss something?

I like where you're going with this whole re-designed polymer lower thing - way better than an exact replica of the aluminum piece - but I want to know about the SCW stock.  

How and/or where did you get an SCW stock and/or did you manage to fabricate one on your own?

~Augee

Got to be careful here. Federal law, specifically Title 18 Ch 44 Section 922p, states (basically-and I'm paraphrasing to save space) that it is illegal to manufacture any firearm or major firearm component (barrel, slide/cylinder, or receiver/frame) that is not as detectable by a metal detector as a mock up made of 3.7oz of stainless steel in the shape of a pistol,
I believe this has generally been applied solely to handguns, and I know I always see it referenced as such, but I'm not as familiar with this section as some others.

Can you use any other material? I know a boat builder that has a polymer that is 10 times stronger than steel that he uses to pour parts. Wonder if it could be used.

Feel free to PM me the location that you may accidentally lose one of these lowers. I occasionally lose my wallet. If you were to find it, just keep the money in it as a finders fee. ;)

As soon as it prints you would be in possession of a firearm on school property. That may or may not be a problem in your state.

Yep they have ones that do Laser-Sintered metal. But those babies run upwards of $250k and up, for obvious reasons. Metal parts are bomber and super strong.

For folks like me - who HATE seeing the market get gouged every time there's a threat of a ban, we ought to have an alternative to placing back orders on over-priced parts. The lower receiver is a pretty easy to make part, so why not?

Thanks Sand! I've made 4 of them so far. Getting better at it each time

Actually the "cut up" ones are lowers that failed to print right, so I stopped them before wasting plastic...

The say LTS on the left side, and THOR on the right side.