Gents, many of you probably saw the article about the UT law student who 3-D printed a lower and broke it after 6 shots with a 5.7 upper.

Weak sauce teasip... weak sauce.  

Since I'm bored babysitting some technicians at work over the night shift, I have decided that the world needs a 3D printed lower designed with 3D printed ABS plastic in mind.  I plan to modify the solid model of a forged lower to give it the strength needed to function like any forged lower (or at least have a life in the thousands of rounds, not 6).

I have higher strength Ultem material, but I've decided to go with ABS because its cheaper, more common, and paint/epoxy will bond to it.

The reason I am asking GD for solidworks files is because I'm at work, and all of the sites I have found to download them are blocked on my work computer.  If you have the files, a buffer tube and stock would also be helpful in doing some FEA to run some load cases on the prototype lower solid.

I have a .iges file that fails a feature recognition every time I run one.  I'd like a .sldprt file with the features present so I can modify them more easily and not have gaps etc in my model.

If you have what I'm looking for please PM me!

Once I have a working rifle I'll post details about it along with the theory that went into the design.  The goal is to have a set of instructions for anyone to print a lower that will actually function long term.  I will certainly share that with my arfcomrades.

I have an AR15 and an AR10 lower Solidworks model.  And my own rendition of the AR15 as well.  

PM inbound!

Here for the show.  

In on this, I thought about giving the dimensions to our cad guys at work ( one is a gun guy too) but we have been way to busy to just fart around with fun stuff.

Tag for a link. Thanks in advance.

tag

Search Grabcad.com for the Thor Lower reciever.

you are going to FDM a lower?  I wouldn't risk a job to print something that could blow up in your hands, but good luck.

I've got upper and lower models, and a few other things.  Check out CNC GUNS  They only have Edrawings, .IGES and drawings, but I imported all my files into SW as .iges.  Haven't taken the time to model them from scratch to have a working feature tree, but that's all I got...

Chargerkid hooked me up. Grab cad is blocked on this computer.

sweet

The lower isn't what keeps things from blowing up in your face.  The highest loads it see's are during recoil.

This will not be printed using work resources.  I have a friend who owns a machine shop who will print it for me.

I have both Solidworks and Inventor files for the AR15 lower.  I used them for the .50 BMG bolt action upper I designed for my advanced engineering graphics class.  You can also google and find them.  
 

Biggerhammer.net used to have some stuff but I'm not sure exactly what. It's been awhile since I was there.

Most of them are .iges or other non-native formats.  He wants a native file with a feature tree.

You had better do the printing yourself, lest your friend be charged with manufacturing a firearm without a license. Or, he could simply print it for himself, and you could document tests on his gun.

I understand.  The problem is if you have a KB that receiver is coming apart, quickly.  Glad you have cya.  Let me know if you want design help.

Ohh arfcom...

I will be sitting next to the machine with my laptop hooked up to it while it prints.  So it's fair to say I will be the one making it.  I'm just using a friends equipment.

Awesome, I knew someone here would do it!

I need to make a billet lower

i know jack crap about plastics, but there was a dude on YouTube who CNC'ed a block of delrin into a lower.  I can't remember what he used for an upper, .223, .22LR or what?

are you gonna use Solidworks Finite Elemental Analysis on it?  That can take a lot of computer time...
 

My laptop has a Penryn engineering sample processor, even though it's 3+ years old, it's pretty darn fast at number crunching.

I will be watching this.

Sometimes I wish I had gone Mech. Eng. rather than Industrial Design, sometimes

Caboose of its not too much trouble could you explain to us the modifications you make to the lower?

I had one programmed in mastercam for the 1st side out of bordum at work, i lost it when i left, i was just thinking today i need to get a file to cut one, i have tons of aluminum and a high speed mill at my disposal, why not


Can i get a file pm'd?

The polymer recievers I've seen broke at 45 degree angles inside the radius at the back of the lower where the buffer tube attaches.  It looks like the bending and axial loads from the buffer tube are cracking them there.

I'll increase the cross section and possibly make a cut out to epoxy a piece of steel in there to stiffen it.

I will also epoxy in metal inserts for the pins so I don't have metal rubbing on plastic.  

The rest will just be optimizing the geometry for the material.

This won't simply be print and shoot.  More like print, epoxy metal hardware in as part of the assembly, and then go shoot.

Do it! Then post pics.

Psh, I'm thinking HD video of a 60 round surefire mag dump

See these are the kind of people I like to work with, none of this pussy footing around

You don't need a designer do you, I can make it look pretty and I'm really good at breaking stuff

You might try a SS insert.  Form up a sheetmetal insert, press in place right after the part builds, apply heat … no epoxy needed.  Watch critical dims.

You will see different results from a FDM part than inject mold … more likely to see separation between the layers than stress fracture at the corners.

some of us might be putting together an Open AR project over here in this other thread, bottom pg1:



http://www.ar15.com/forums/t_1_5/1400787_.html&page=1&anc=37070363#i37070363