Gunner Quinn
(Continued from Part 3.)
“Am fear nach gheidh
Na h-airm ‘nam na sith,
Cha bhi iad aige ‘n am
A chogaidli.”
(Who keeps not his arms in times of peace,
Will have no arms in times of war.)
– Scottish Gaelic Proverb (with a hat tip to James Tarr)
Other Filaments
Nylon
Reportedly, nylon ranges from challenging to very difficult to print. It is temperature-sensitive and can warp as it cools. It requires temperatures at or close to 300° C., which many 3D printers cannot reach without modification. It also gives off fumes during printing. This and its temperature sensitivity make a printer enclosure—preferably with special ventilation—almost mandatory. The high temperatures may shorten the service life of printers not designed for those temperatues.
Additionally, nylon is also very moisture-sensitive and must be kept very dry before and during printing. To top it off, nylon tends to be more expensive than PLA and PETG.
On the other hand, nylon offers great strength and flexibility. It also can easily be dyed in a wide variety of colors. There are 3D printer hobbyists who have no trouble printing in nylon. If you need nylon’s attractive properties, go for it! I would suggest waiting until you are very comfortable printing in PLA before plunking down the bucks for printer upgrades—or a new printer—as well as pricey filament.
ABS
Acrylonitrile Butadiene Styrene (ABS) is a fairly strong plastic used in industry. Lego® bricks are reportedly made of ABS plastic. ABS is not for beginners. Although it may not require high temperatures, it is temperature sensitive, and fluctuations can result in bad adhesion between layers. It also gives off fumes during printing, which means that an enclosure with special ventilation is strongly recommended. It does not seem to be expensive, and the colors look vibrant, but poor shock resistance, the fumes, and its reputation for being difficult to work with have caused me to give it a pass.
SOME SPECIFIC PRINTER SUGGESTIONS
Ctrl+Pew has been a prominent member of the 3D-printed gun community for a very long time. His website is a great resource for anyone interested in building their own firearm parts. His “Getting Started Guide,” which is regularly updated, has recommendations of specific printers, ranging from low-cost to high-dollar, with solid evaluations.
He also lists—in the File Drops section of the site—new designs that have been added to The Gatalog, along with links. I frequently check the New Betas section, to find out what’s being tested now and will be showing up soon at The Gatalog. One notable item that’s coming—under the name “Hotbox”—is a DIY filament dryer.
HINTS & TIPS FOR 3D PRINTING SUCCESS
Start with PLA!
PLA filaments are very forgiving and give great results with a variety of printers. Many gun part projects were designed with PLA in mind.
Level Your Bed and Set the Nozzle Height
The print bed must be level—not with the ground, but in relation to the print head—for successful printing. This is probably the number one reason for printing failures, yet many 3D printer owners don’t understand bed leveling.
Nozzle height turned out to be the factor that doomed my early PLA prints to failure. Once it was adjusted, I was able to get PLA to stick to my print bed. When I switched to PETG, I had to move the nozzle up slightly for best results. “DrVAX” (Irv Shapiro) on YouTube has posted the best explanation of bed leveling and nozzle height that I’ve seen.
Prepare the Print Bed
Different filaments work best with different print beds and preparations. I use a textured, flexible, magnetic PEI print bed. For PLA, I found that cleaning the print bed with dish soap and applying a thin layer of Elmer’s “School Glue” purple glue stick—along with figuring out the proper nozzle height—worked very well.
With PETG, I followed a suggestion from a very helpful person at GreenGate 3D Filaments and put a layer of blue painter’s tape—laid down carefully, with the parallel rows of tape just touching one another—and covered the tape with a thin layer of Elmer’s “School Glue” purple glue stick.
Where I had trouble getting PLA to stick to the bed at first, PETG has a reputation for sticking too well. The tape-and-glue-stick method is intended as a release agent. I’ve read about PETG objects destroying print beds when they were finally peeled off. The PETG objects that I print often have pieces of tape firmly attached to the bottom of the print, after removal from the print bed. They can be scraped off, but it’s like the tape was glued to the PETG with a high-quality contact cement.
Start Small!
Small projects will help you learn faster! Little figures, small “calibration cubes,” etc. will help you “dial in” in your setting without wasting large amounts of filament in big failures. In gun terms, pieces of rail for attaching to AR-15 handguards, or 1911 grip panels are easy “gun prints.” Try graduating to an AR-15 pistol grip—or something similar—when you’re having consistently good prints with smaller objects.
Keep Records
Notes about your projects—along with the slicer settings and the end results—can help you avoid repeating mistakes. Your notes will help you track your progress as you “dial in” your settings and printing methods. Notes are also helpful when returning to a filament you haven’t used in a while.
Try Printing Slowly!
After some successes in PETG, with 1911 grips and the like, I tried printing a receiver. It was a big failure, with a mass of “stringing” replacing part of my receiver! I researched and found someone with similar problems, who tried printing PETG “hot and slow.” I tried raising my nozzle temperature a little, to 245° C. and cut my print speed way down to 25mm/s. It worked! Stringing is now minimal, and my prints look great after easy cleanup.
Keep Your Filament Dry
The filaments used in 3D printing are hygroscopic—meaning that they absorb moisture from their surroundings. Some filaments—like nylon—are more hygroscopic than others. “Moist” filament does not print well.
If you’re in a humid environment, it will be challenging. I keep new spools of filament in their sealed plastic until use. In a more humid place, I’d be using airtight boxes and desiccants for spools between uses. Special heaters are available that hold a spool and keep it at around 50° C. They can be used while printing with the spool.
I’ve kept my opened PLA and PETG spools in a dry, air-conditioned environment indoors. I do use a heater on spools before and during printing, and I’ve had no problems that point to humid filament.
Use Enough “Walls”
The thickness of the “skin” of your project is set in the slicer. Most gun projects use at least 6 walls for top, bottom, and sides, for a sturdier project, even if you choose 100% infill. I generally use 10 walls in gun parts projects.
Print Most Gun Parts at 100% Infill
The instructions often suggest an infill level. For receivers, ejectors, stocks, braces, and other parts that are stressed in usage, this is usually 100%. Some parts, like a chassis that holds a .22 LR receiver, may be okay with infill between 50% and 90%.
Print in the Best Position
Position the object (in the slicer software) in the best way possible for strength and for dealing with support material. This can make a huge difference in your project.
A 3D-printed object is generally weakest where the layers join. I printed a pen—just as it was shown in Thingiverse—standing vertically on the print bed. In terms of the layers it was like a stack of washers. The pen looked great, but it snapped in half with little effort. It broke between two of the layers. I then printed another pen—this time laying down on the print bed and using supports—and I could not break it with my hands.
Support materials keep parts of the object from collapsing, but they can leave a rough surface where they were attached to the object. The uppermost surface of a print often has the best finish of any part of the object.
These factors are why you might decide to print a “Glock” frame upright, with the top of the frame parallel with the build surface. The layers would be positioned for best strength, and the part of the frame that has to be smooth to fit close to the slide is on top. Also on top are the cavities where parts will be inserted. There should be little or no need to remove support material from the spaces where parts will be installed. The areas that need to have supports removed would be the simple surfaces on the underside of the trigger guard, the undersurface of the dust cover, the top of the space inside the trigger guard, and in and around the magazine well.
“Flip” Objects When Needed
Some gun objects—like folding mechanisms or pistol grips—may need to be “flipped” to work for you. The Booligan hinge box and brace are designed to fold to the left. I wanted a right-folding brace, so I needed to flip both parts. This is done in the slicing program, so you don’t need to pester a designer with comments like: “Please make a left-handed version of this grip!”
I couldn’t find the command to flip the parts in the menus of Prusa Slicer, but a right-click on the object allowed me to “Mirror” it. It took a moment’s thought, to make sure I mirrored the hinge box and brace in the right dimension (X, Y, or Z). Once I figured it out and mirrored the two parts, I was able to print a right-folding brace!
(To be continued in Part 5.)
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