by M.B., Survival Blog:
(Continued from Part 2.)
Printable Frames and Receivers
These projects generally use a 3D-printed frame or receiver, which is combined with firearm parts to create a finished firearm. Some of these designs can fire over 1,000 rounds without the frame or receiver failing. Projects in this category include a variety of AR-15 lower receivers, such as the UBAR2 and the Hoffman Tactical SL-15, a vast array of Glock frames, like the FMDA DD19.2, Ruger 10-22 receivers, and a variety of MAC11/9 lower receivers. There are also projects based on Smith & Wesson M&P pistols, Ruger pistols, Beretta pistols, CETME rifles, the Kalashnikov (“AK-47”), and much, much more.
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For many builders, the biggest challenge in a project using a lot of firearm parts is the sourcing of those parts, especially if it’s for a firearm that’s out of production. The media may rant about the availability of “parts kits” or “builder’s kits,” but the truth is that for many firearm projects, the builder must order each part needed and may have trouble finding some parts.
WHAT TO LOOK FOR IN A 3D PRINTER
The first question is: Open Source or Proprietary? “Open source” printers use common components, so the end user can easily purchase—or print—replacement parts, such as knobs, belts, etc. It also makes upgrading to a better hot end, heat break, etc. easier and less expensive. Open source devices—unlike proprietary products—do not have a planned service life, after which parts become less available.
The classic 3D printer in the gun community has been the Creality Ender 3 (and many other brands made with Ender parts), although that specific printer is now part of an older generation. Your best bet, if you want to go open source, is to do some reading—on Reddit and/or in 3D printing Web forums. There are other printers that may serve your needs better while still being open source. On the other hand, Ender printers continue to sell!
My printer, by the way, is made with Ender parts. It has been very easy to find the few parts I’ve needed for a few small upgrades, and for maintenance.
Software
One recent concern—especially after the public murder of the CEO of United Healthcare by an assassin using a pistol with a 3D-printed frame—has been that the gun ban lobby has been eager to ban 3D printing. As related in a recent article, some software developers are working on programs that are supposed to detect gun parts being made, block the print operation, and may also inform law enforcement. The focus thus far appears to be targeting cloud-based printing management.
No matter which printer you choose, be aware that the firmware running it, and the slicer software producing G-code for it, are critical to your privacy. As of this writing, I’ve heard of no issues with the very popular Cura and Prusa slicer applications, nor with the firmware in common use in open-source 3D printers.
Printer Size
It’s not difficult to determine—before buying—if a printer is large enough for you. Slicer programs can be set by the user to work with any popular printer model, so set it up for the printer you’re considering. If it’s not listed, choose one with the same build space. Now look for the largest object you are considering. Perhaps it’s a receiver or a chassis for a 10/22 or other firearm, or maybe a handguard or a stock. Open the STL file in the slicer and see if it can be moved and/or rotated to be within the build area. Check the instructions to see if a particular part of the item should be uppermost. Don’t forget that you can also raise one end of the object up—taking advantage of the available height in your build space. Just be careful to avoid layer lines running in a direction that weakens the build.
Many projects are designed to be printable on an Ender 3, which has a build space that is 220 x 220mm and 240mm high. Therefore, whatever you decide on, I don’t recommend any printer with a build space smaller than 220 x 220 x 240mm.
Bed-Slinger or Bed-Dropper?
FDM printers have to be able to move the print head—in relation to the object being printed—in three dimensions. Bed-slingers move the print head left and right, on a rail (X dimension) and raise that rail as the object is printed (Z dimension). The print bed moves back and forth (Y dimension).
Bed-droppers have the print head mounted near the top of the printer, where it moves in both the X and the Y dimensions. At the start of a printing operation, the print bed is raised up to almost touch the nozzle. As the print progresses, the print bed drops straight down (Z dimension), while the print head stays at the top of the printer.
