Hello Everyone,

I was getting ready to order an 80% lower for a .22LR build. Then I stumbled across an article discussing 3D printed lowers. That peaked my interest.

I have very little experience with 3D printing. I have purchased items that were 3D printed and found them to be very fragile. Reading that they are printing lowers make me think that there must be a better/stronger method of 3D printing than what was used on the pieces that I received. They broke apart along the printed layers.

I have toyed with the idea of buying a 3D printer in the past but wound up just buying parts that someone else printed.  If I could print a decent lower that would be one more plus for buying one.

What would be the minimum machine you would recommend?

What methods of printing and choice of filament choice would be best suited to printing a lower and avoid the issues I have had in the past with 3D printed items?

I am reasonably tech savvy don't have an issue with that end of it.

Thanks.

S.

I'm a 3d printing slut, but this.^ Money more properly invested.

Also get a printer, and you can play with it. But don't get it to just print a receiver.

But, but, but, I heard the dumocraps saying that anyone could print an entire "ghost gun" on their kitchen table!  I even got schooled by some gun ekspurts on the yewtubez that these guns were 100% reliable & could pass through any metal detector!  

Actually the current record is well, well over 6 rounds, well over 6 mags.

Among the best is improved versions of the original "bolty" lower. (Multiple printed pieces that bolt together to form a lower, allows better printing optimization compared to printing as single unit especially in the direction the "grain' of the print is running in  certain parts and using the metal bolts to strengthen the weakest points.)

But, yah, 80% lower and mill it out is still a MUCH, MUCH, MUCH better option.  I was considering trying to do a 3D printed thumbhole stock version of the CAV-15 lower which might have held up.

But the combination of the costs involved and the fact that KE-Arms is finally going to make a V3 of the CAV-15 lower which is what I was really after the project has been shelved.

Now if KE-Arms falls through then it might get pulled back out and dusted off.

Thanks for the reality check


Imagine that. .... An incomplete and inaccurate news story...........

Back to the original plan of milling an 80%.

Anyone here printed jigs to hold a lower for engraving?  I have been wanting to engrave my lowers using my X-Carve machine and not found anyone selling them.

You just need a better printer.

google "3d printed rocket nozzles"

On Twitter there is an entire group of 3D printing firearm enthusiasts. They are pretty far past 6 rounds (think several thousand), and are also showing some really amazing functionality using electro-etching to create rifled barrels from steel tubing.
Some of these designs are pretty clever, and there is always the old standby of using specific filament to make lost-wax type molds for aluminum receivers.
They post a great deal of their efforts on YouTube.
It’s worth a look if you’re interested.

I have done more than a few 3D printed lowers.

Here's some quick points to consider -

Material matters.  Printers can print with all sorts of plastics.  More expensive printers can run at higher heats and have encloses and heated beds and can print with better  materials.  In general, PLA is a bad choice for an AR.  Like you mentioned, its too brittle.  It also doesn't handle heat well.  Nylon and ABS can be used to make decent lowers.

Design matters.  the mil-spec shape of an AR was designed for aluminum and to be made on mills.  If you try to use 3D printed plastic to make the exact same physical shape, it won't work well.  You can design a lower that is designed to be printed out of plastic.  The shape that works well with printed plastic will not be the same as a mil-spec lower.

Orientation matters.  You can orient a print different directions on the print bed.  Some directions make it easier or faster to print with less wasted plastic, support material, and bridging.  Printed parts have weakness related to the direction of the "grain".  Often the direction that makes the print stronger and the direction thats easier to print are not the same.  You may have to change you design or orient the model so the grain runs a certain way to make it stronger in the long run.

Tune your upper!  With a properly tuned upper and buffer setup, you can get at least 1000 rounds of 223/300blk before the lower cracks.  So far, mine have all eventually cracked at the rear takedown pin holes.    If you continue to shoot it, eventually the back section of the receiver that contains the buffer tube will snap off and you get parts exploding rearward towards your face.  With a 22lr build where there is no huge bolt carrier and buffer recipricating and slamming into the back of the buffer tube, I think 5k rounds would be very doable.  If I were betting money on it, I'd bet this gray lower I printed below would easily last 6k+ rounds.

Time.  The physics behind forcing melted plastic through a pinhole can't really change that much.  You can only extrude plastic so fast.  Most lowers take a day or more to print.  They cost about $5 worth of plastic, which is negligible, but 24+hr of machine time.  If you consider the machine time, its a lot cheaper to just buy a poverty pony that will be able to handle more abuse.








You're behind the times with those numbers.  3D printed lower and milspec everything else will run through more ammo than you can carry in your loadout.

I have heard that there is at least one 3D printed WarFairy P90 Style 22-lr Only Bullpup AR-15 Lower out there that has tens of thousands of rounds on it that hasn't cracked yet.  Can't confirm but I've heard the claim a couple of different times and the way that lower CAD file is setup and it being 22-lr only it makes sense that if anything would go that long it would be that combo.

I was thinking of trying to do a thumb-hole stock version for 3D printing similar to the CAV-15 lower only with a thumb-hole stock so the pistol grip is part of the stock which is part of the lower all one piece with both a solid trigger guard and lower fingers hand guard (like a Famas 2nd gen) specifically to do as much as possible to strengthen that weakest point at the rear pin hole.

Like this:


Mainly because I was getting so desperate that the CAV-15 lower was no longer available except on the used market and at inflated prices.  But since it is being reintroduced by KEarms I've shelved the idea for such a lower for now.

The problem I see with that is there aren't very many home printer with that big of a build volume.  Even if you had one, thats like a 5 day long print.  

3D printers are fine for certain rifle accessories, but at least with FDM printers, the weak link is layer adhesion. You can optimize strength by carefully evaluating which way the layers should go, but you're still relying on layers that are laid down separately sticking together. The stresses in the components of lowers would rather easily jar those layers apart.

I'm currently running 3D-printed AFGs and I even designed and printed a "door" for the hollow end of a Hogue pistol grip to use it as storage.

OP, take a look at War Fairy's Charon.  It's got an integrated bullpup stock that reinforces the critical stress area of the AR lower btwn the buffer tube and the rear takedown pin.  It can also be printed in separate parts on smaller printers and glued together.



As a Mod, you should really try to keep up.

ETA:  Were you thinking of Orion's Hammer's Pine ABORTION wooden lower?  That lasted for 3 rounds, made of milled soft pine.

Yup, very true.  I was considering three options, segmented print and glue "WarFairy" style, segmented print "Bolty" style, or biting the bullet and "going big or go home" and purchase a printer big enough to print as a single piece or some combination thereof.  I was able to find a printer kit where you bought the print head unit with the nozzle and servos and drive components and assembled the frame to whatever scale the user needed and programmed the movement limits for how big of a frame you built for your needs.  That became the top contending option.

But as I said KEarms is coming to the rescue, so the project has been shelved.

That is exactly the problem that I have had with 3D printed objects in the past.  Failure between layers.

I do see great application for accessories printed but I think that I will wait for a bit before venturing down the printed lower.

I am still on a quest for a 3D printed jig to support my lowers for engraving.

This may be an indicator of too low printing temperature or other slicer settings.  For my printed lowers, printed at 100% infill, my layers are running horizontally and they all have a crack form vertically.  The crack runs through a bunch of layers.  They all stayed stuck together fine.

It may also depend on the material you use. CF infused PLA is fairly strong. I use PETG, which I find to have excellent strength along layers, but it tends to be stringy unless the printer is well tuned.

My Glock mags are terribly stringy.  Got my 1st one to work and have printed 3 more but there's a lot of cleanup to do.  Have only managed to load 15 rnds of brass in a 17 rnd mag.

I sure ain't no guru but I do know that even a very modest 3D printer will print a completely serviceable -printed- lower.   It's all in the settings: temperatures, speeds, layer height, fan settings, etc.)  You just have to google around, watch a few youtube videos and mess with your settings until you get the printer dialed in for a particular print job.  


I'd post a picture but I'm not sure how to do that yet (I'm the FNG on the forum)

AR15 Receiver Engraving Jig for X-Carve

I've been lurking for a while, waiting for parts to build my first AR. I've got a couple printers, and I stumbled on your post around the same time I found the Thingi, so I figured now would be a good time to join ARF.

That is exactly what I was looking for. Now to get it printed........ I chuckled at the description.  I need that piece for engraving AR lowers with my X-Carve :)

Be careful with the AR's....... I had never been around them. Always been a bolt gun guy. Then I got curious...  I bought one to tinker with and got the bug...  I have  two in the closet,  one on the build bench and two custom barrels in the works for two more. It is an addiction  :)

Just wait till you get to the point where you are cleaning out the camp trailer to get ready for summer and you find an AR in the back of the closet covered by coats that you forgot yo even had !!!

Gimme a break  :) I am still a newbie.  By the end of the year I expect to need a new gun safe :)

Saw a couple of 3-D printers set up @ the gun show today, hawking their 3-D printed mag loaders.  I showed em my Glock mag, and mentioned there was a lot of clean up, as not only are there a lot of strings on the outside the parts that have to be cleaned up, there's a lot of strings on the inside of the mags that have to be filed away as best as I can.

They pointed out that stringing was due to the head being too hot - Ivan specced 230 degrees C for the Menendez Glock mag, which is what I've been running.  Should I go cooler?  Will that interfere w/ the adhesion of the layers?

Depends on the plastic, your printer, your settings, and your environment.  Even different colors of filaments from the same manufacturer will print cleaner at different temperatures.  You can try playing with retraction and your cooling fan if you're using one.  Lots of little tricks.  Its not as simple as downloading a stl, slicing it with some canned settings, and sending it to the printer.

While stringing can be a result of many factors, too high of a temp and not enough retraction are the two biggest. I think 230 is waaay to high even (for PLA). I print that at 190 and the layer adhesion is fine.

I'm running 230 on PLA for the Glock mags b/c those were Ivan the Troll's settings, and he published the Glock mag STL files.  I just printed a portion of WarFairy's Charon, ran @ 200 degrees, very little stringing.

Well, I thought thought I had found someone to print it for me but he has gone silent on me.

Any volunteers? I have a few sheckles in my toy fund to cover time, materials and postage.

Shoot me an email: sgregg64 at Gmail.com

Doh! I thought you had a printer. Gimme a couple days, and I'll knock a set out for you.

Gunny McGunsmith has 1200rds on one. It has now developed some cracks, but it's a far cry from 6.

No.  At times I wish I had one.  

Thank you.

What was the recommended filament though?


230 is high for PLA, a little high for PLA+, but in the range for PETG

Just using PLA, which I believe is what Ivan the Troll was using.  The label on the Atomic Filament I was using said up to 230 degrees.