3D Printing PETG Lower

[Anonymous No.1527442]

recently got the Fosscad files and decided to print in PETG an AR15 lower for 300 Blackout.

Seen vids of this working nicely and wanting to make sure I'm doing this right. If not no big loss just grab a cheap lower for 60$

anywho the question, is 100% infill enough?
do I need to add any top/bottom layers?
Current settings: 100% infill, bed is 70, hotend is an All Metal Hotend from microswiss temp is 240, layer height is .25, using Novamaker PETG

Also this is more of a "to see if I can ordeal" than anything.
Thoughts and tips is appreciated my dudes.

[Anonymous No.1527464]

>petg
Lmfao might as well use ptu rubber filament
Use abs nigger and it will still perform like shit.

[Anonymous No.1527481]

>>1527442
it's a lower receiver, it doesn't do anything fancy. doesn't withstand explosive forces. You could make one out of clay, dry it and fire it in a kiln and it would still work if it was still dimensionally accurate after firing.

Think of a lower receiver as an overcomplicated jig or bracket that holds a bunch of other shit together in the right place.

[Anonymous No.1527492]

The largest force is on the buffer tower, almost everything else doesn't matter. That's why on most plans or plastic production lowers the tower is beefed up for longevity.

[Anonymous No.1527501]

OP here
ABS shrinks too much and I figured I'd give PETG a try.
the pic shown is the non reinforced model from fosscad, lemme see if I can dig up a reinforced model since they all have the extra material on the buffer tube area.

[Anonymous No.1527504]

this is the reinforced model, well a reinforced model.
the buffer tube area in the back is bulked up heavily.
Any clue if it will hold?

[Anonymous No.1527646]

>>1527504
those work ok

[Anonymous No.1527647]

>>1527504
Do you also print out the super long take down pins?

The buffer tube is why lowers should be metal. If you are completely set on using plastic without metal reinforcements, just print up a shitton of receivers and get good at swapping the reusable metal parts. You could use a plastic receiver to make a mold for a metal one, but it's cheaper to just start with a metal 80% lower.

I blame the liberal media. There was so much noise about printable guns that gullible people started to believe the hype. You can make a functioning gun from a 3d printer, but in the same sense you can carve an equally durable one out of driftwood. Unfortunately, the truth doesn't sell as well as sensationalism so everybody "knows" you can just print up a gun.

Anybody try making a lower out of JB weld? I'd do it but I'm not drunk enough.

[Anonymous No.1527725]

>>1527647
I was planning on a brass threaded ring for the buffer tube if need be and the internals all metal with the Geissele trigger I have just to see if it functions and or lasts

[Anonymous No.1527733]

>>1527725
The break typically happens close to the hole for the rear takedown pin. Will you weld metal to the brass ring that runs through the sides of the receiver? Otherwise the brass ring does nothing to keep the receiver from breaking in half.

[Anonymous No.1527739]

>>1527733
if need be I printed off one already, got another one almost done.
one for a ring and the other for without just as a general test.
From what I've seen they look like they last somewhat decently as long as its PETG or ABS or stronger so I'm hopeful

[Anonymous No.1527748]

>>1527739
Pic related is how one company reinforces that area. Go wild. Lowers are fun.

[Anonymous No.1527894]

>>1527748
thats pretty cool actually. I wonder why it has those smaller divets in the material

[Anonymous No.1527992]

>>1527894
increases turbulence when you throw it at someone :^)

[Anonymous No.1528169]

>>1527442
that shit will not hold up, you have to use nylon

[Anonymous No.1528174]

>americans can 3d lowers
IT'S NOT FAIR IT'S NOT FAIR WHY DO OUR LAWS SUCK SO MUCH IN THE EU

[Anonymous No.1528183]

>>1527442
markforged 3d printer, cuts pieces of glass fiber off and puts them into the print for strength.

[Anonymous No.1528189]

>>1528183
>markforged 3d printer
gotta request a quote for price means its too rich for my blood lol

[Anonymous No.1528190]

>>1528174
what the government doesn't know won't hurt them.....just you

[Anonymous No.1528193]

>>1528189
really? could swear I saw a starting price listed a few grand

[Anonymous No.1528214]

>>1528189
Starting at $3,499

[Anonymous No.1528237]

>>1527442
Google research how the shelling process in a slicers works. You can't go over 100% infill, and at that point top/bottom layers are irrelevant except maybe for concentricity.

Bed could be a bit lower temp (I use 60 for PET), and you're better off doing temperature tests beforehand to check if that 240 number is correct for your specific setup and filament. I'd err on the high side so the layers fuse together properly, which is also why I'd use as big of a layer height as possible. You're probably using a .4mm nozzle in which case I'd bump it up to .3mm layer height, you could use a .8mm nozzle but then you're losing details, possibly critical dimensions, but you could go to a .6mm layer height - although that will probably be well over the edge of your extruder and heating element. What printer are you using?

>>1527464
Various testing has shown that ABS is much weaker than PET in terms of E-modulus and maximum tensile strength.

>>1528169
Fiber reinforced nylon is indeed 2-3 times stronger than PET, might try that if it fails.

[Anonymous No.1528314]

>>1528174
Blame Franz Ferdinand.

[Anonymous No.1528365]

>>1527894
>>1527992

;D

Like a golf ball. So when it jams after the first shot you can get a good spiral as you run from hundreds of years of proven metallurgy

[Anonymous No.1528366]

>>1528174
They made it illegal but it's to late now. The internet has it

[Anonymous No.1528368]

>>1527894
lower weight, place for glue or melted material or simply looks

[Anonymous No.1528387]

>>1527504
Why wouldn't you add a web like this? Or at least on the left side of the gun; I forgot about the manual assist button. I would also beef up the area around the front pivot pin and maybe include a depression to glue in a metal bushing. Or actually nvm if the rest of the area below the hole is solid then it should be fine.

IMO it's stupid to make a 3d printed part to match a design made for metal, like the threads for the buffer tube probably won't hold up. The design of the gun needs to be worked over specifically for 3d printing. Like if the buffer tube had a flange so that you could insert it from inside the gun and then the upper receiver would press on it when the gun was assembled. And if the flange was square and sat in the square depression then the tube wouldn't rotate.

[Anonymous No.1528607]

>>1528366
they took it down under ITAR laws, but the creator won the lawsuit on first amendment grounds
blessed country

[Anonymous No.1528655]

>>1528387
>Why wouldn't you add a web like this?
Because that's the interface between the lower and the upper. The rib would interfere.

[Anonymous No.1528656]

>>1528174
I thought EU laws were more along the lines of pressure bearing components. Like, the illegal part may not necessarily be just the lower, but also the barrel and bolt.

[Anonymous No.1528773]

>>1527442
100% infill is a meme btw. For better strength, add wall perimeters. It saves time, plastic and gives you a stronger, more dimensionally accurate print.

Although you would still want a high infill for a lower, you never want to go to 100% for just about anything ever. I would say go with 50% and no less than 5/6 perimeters.

PETG should be just fine also, but I would love to see someone 3D print a lower in polycarbonate. It is even stronger than Nylon without the flexibility which is perfect for mechanical parts for weapons. It needs crazy high temps though (something like 290 hotend and 150 bed).

[Anonymous No.1529069]

>>1528773
Printing polycarbonate is a pain in the ass and yeidl disappointing results in terms of layer adhesion and part strength.

t. tried to print bullets out of bulletproof glass

[Anonymous No.1529138]

>>1529069
git gud

[Anonymous No.1529157]

>>1529138
He's not wrong. Polycarbonate seems to aerate during the extrusion and it becomes not considerably stronger than pla/abs.
Fiber infused filaments are what you need for a really strong print, even some filaments that are just some short carbon fiber strands in pla have proven to be incredibly strong.

[Anonymous No.1529491]

>>1529157
PC is one of the strongest filament materials available right now WHEN USED PROPERLY. This isn't up for debate.

CF also destroys your nozzle unless you use some hardened shit.

[Anonymous No.1529503]

>>1529491
>have to get an all metal hardened nozzle and barrel.
vs
>having to get an all metal as well, because high temps.
>fiddle with the finicky stuff. It'll detach from the bed. It'll bubble. layer addition is either incredibly strong or non-existent. Part topology may cause it to fuck up.
>If it bubbles, the layer's hooped and possibly the entire part.
>high print to glass differential.
On paper it may be the strongest, in practical terms, it's worthless with the existence of better petg-carbon filaments.

[Anonymous No.1529717]

Use PC, PEEK or PEI with a 5000$ printer imao lol

[Anonymous No.1529719]

>>1527464
PETG is stronger than ABS you mong

[Anonymous No.1529722]

>>1527442
>is 100% infill enough?

nah you want 169% infill

[Anonymous No.1529724]

>>1528655
so bulk it up without interference, use upper without forward assist
just make it so upper can slide into place
back end will look fugly but will work

[Anonymous No.1529869]

>>1528314
Take me out

[Anonymous No.1529877]

>>1529724
Or you can just use the lowers /k/ designed four years ago and be done

[Anonymous No.1529940]

>>1529724
That is exactly what the designer in the image you were replying to did. The areas most prone to failure appear to have been thickened. Can't quite tell from the image if it'll still take standard pins, but honestly that shouldn't be a problem at all to source. A normal receiver looks like pic related

[Anonymous No.1529942]

>>1529877
I wonder, are those in the do/k/ument? There's a torrent for it on /t/ but I haven't yet looked into it.

[Anonymous No.1531193]