It’s been a long time since we did one of these updates, so here are a few things we’ve picked up here and there.
Print Now, Rest Later
Here’s a practical print task: a 3D printable cheek rest for an AR-15 pistol. (Well, to the extent that an AR pistol is practical). As we understand it, if you shoulder the weapon (say, with a SIG brace) you are violating the SBR laws, but if you’re cheek-resting you’re all tickety-boo. This image is a rendering; a final print will have some striations to it, from most printers using the most common 3DP technologies.
Checked as of last night, the files are here: https://www.sendspace.com/file/386tvq
Happy printing & shooting.
About those striated parts
One of the problems with 3D printing, especially the Fused Filament Fabrication / Fused Deposition Molding type that is common, is that the parts often display layering, striations, and other artifacts that add up to a lousy surface finish. There are several ways to smooth 3D prints.
- Mechanical Smoothing — this can be sanding or particle blasting; each has its pros and cons. Sanding is limited in how small a part you can do, bead blasting in how large. Bead blasting always produces a matte finish, although the coarseness or fineness of the finish depends on the blasting media. On a part large enough to be practically sanded, sanding can produce a finish limited primarily by time and the cost of skilled labor.
- Chemical Solvent Smoothing — this involves exposing the part to solvent vapor. For example, for ABS, acetone vapor either cold or hot (hot vapor has definite safety limitations and concerns, but can produce a superior finish). Acetone doesn’t work with PLA as it’s not acetone-soluble. Acetone also reduces the strength of the part: its stiffness is reduced, and it fails under a lower load.
- Finish Coating — for a cosmetic finish, a thick paint can be used to fill layer striations. This will, often enough, loop you back to sanding. This is cosmetic only and subject to wear.
- Epoxy Coating — this does require some skill to pull off, but both fills and reinforces the part. This can be important with some liquid-based and powder-based laser 3D printers whose parts tend to be brittle; coating them with epoxy can make the printed part, in effect, a shear web and form inside a tough, flexible epoxy shell. This is good when the part needs to be employed as is, and not so good if the part is intended to be, say, a sacrificial casting pattern. (In that case, for lost-PLA casting for example, use one of the other procedures). Smooth-on sells an epoxy that’s optimized for this type of use and has several how-to and application videos on the web page.
For more information:
- Lindsey Frick in Machine Design on “How to Smooth 3D-Printed Parts.”
- Smooth-on’s gaudy page on their XTC-3D 3D Print Coating has lots of examples and tutorials.
- Here’s Make Magazine and Instructables with a pair of acetone-vapor tutorials.
- And here’s the story of a guy who went whole hog and built an ultrasonic vapor fogging chamber in hopes it would increase the strength of his prints (it actually weakened them). There’s a link in that article to an Instructable on building his fogger, too.
100 Rounds from a 3DP Pistol
Remember the original Liberator (well, the original 3D Printed Liberator, not the original original Liberator)? It was only good for a few shots. (Unless you were the New South Wales Police, and printed it without reading the instructions, in which case it blew up first shot). What use was it? But as Franklin said on being asked that of the invention of the French aeronauts, the Montgolfier brothers, “What use is a newborn baby?”
Well, here’s a 3D Printed pistol that has fired 100 rounds and is still going. 3D printed AR lowers long ago beat that number, but here’s a pistol that’s all 3D printed on consumer equipment, except for the mandatory weight and firing pin.
We’re not sure whether this colorful print of this James R. Patrick design wants to be a toy, or whether it wants to be a Glock when it grows up.
A Practical Print for Almost Everyone
What’s this? It’s an AR Hammer Block. Use it when you want to function-check that lower you just monkeyed with, without running aground on the Scylla of letting the hammer slam into your expensive piece of aluminum (very expensive if it comes with a stamp), and the Charybdis of using your delicate pink (brown, whatever) thumb to intercept the falling hammer.
A great, practical print. (The website it’s advertising is for a training device to use with your SIRT, not available to the general public yet). Hmmm… the “files” link at PrintedFirearm.com, went to a malware site: adf.ly! And downloaded a malware .exe! We’re not giving you that link.
OK, here’s another one instead, by Charles Lacey:
Files here, Grabcad is not a malware site: https://grabcad.com/library/ar-15-trigger-pull-test-block-all-set-for-3d-printing-1 (You do have to join Grabcad to download files, though).
Lacey also has a chamber flag, or as he calls it, a bore flag, on Grabcad, and a couple of Magpul mag floor plates, including a whimsical Flying Tigers version. We leave finding those as an exercise for the reader.
Large Format Printed Pistol Now Speaks Glock
We’ve showed the Shuty MP-1 before, a 3D printed pistol inspired by the designs of Luty. The pistol made a splash in the media some time ago, with the usual alarums and excursions, dogs and cats lying down together, and all the usual drivel you usually only hear in an election year. (This happened twice, actually — in February 2015 with the original Shuty, and in February 2016 with the improved MP-1).
Less publicized has been the Gluty — as you can see from the image below, it’s a Shuty reengineered for Glock mags. The image tells us it’s been printed but we’re not aware of how successfully it has been test fired — unlike the Shuty.
One of the biggest limitations of the Shuty is its magazine. Adapting to commodity Glock magazines is the easiest way to increase the magazine capacity of this novel firearm. At the same time, the original files, with their included magazine files, allow the creation of a firearm where even the mags are unobtainable.
Of course, that still leaves the barrel as a tough nut to crack. Shuty and Gluty use the standard pistol barrels.
Printed AR Lower
This FOSSCAD JT Vanguard has been around for a while. This recent print, in ABS thermoplastic, shows some of the strengths of the design, and how the venerable AR form factor has had to change to adapt to these new materials and new processes. First shot shows it with an upper in the white. The grip and magazine are also printed.
The grip is also ABS. We’re not sure about the materials of the mag, and wonder if the buttstock is printed also. This next picture shows you just a few of the changes, including the bulkier pivot area, the much beefier buffer tower, and the thick reinforcements along the receiver outboard of the trigger group.
This picture shows the trigger group in place. The reinforcement is clearly visible.
There have been experiments with printed trigger-group components, but so far, they haven’t been very impressive. Materials and processes need further improvements.
Exotic Lower-stock Bipod Combination
This is the Atlas AR-15 lower, by WarFairy CAD. It has a certain FN P90 vibe to it. It’s meant to be used with a free-floating barrel and suitable handguard/rails system.
When one looks at some of these designs, one is reminded of Donald Sutherland’s character in The Dirty Dozen, impersonating a general. “Pretty, but can it fight?”
Atlas Files: https://www.sendspace.com/file/6f0cfo
Finally — MakerBot Hates You
MakerBot continues its extreme antigun position. How extreme? A design for a powder knob for a Dillon progressive reloader was banished to 404.
Funny, their 404 page says, “There is nothing awesome here… yet.” Well, there was before they deleted it!
MakerBot does not want our business? Transmission received.
Consider Ultimaker. Ultimaker advertises on PrintedFirearm.com, which is an interesting site to check from time to time. Beware of any of their links to adf.ly. Two we observed were both delivering malware yesterday, and probably still are.