THREE Dimensions! Ha! Ha! Ha!


So I got a 3D printer in late September, and I’m super excited! Now I can make keychains and random trinkets anytime I want.

Count with me everyone! 1 dimension! 2 dimensions! 3 DIMENSIONS! HA! HA! HA!


Diagram of FFF. Taken from

This model of 3D printer creates parts using the Fused Filament Fabrication (FFF) method. This is a very widespread process where basically thin strands of molten material are extruded to make layers which then build your part from the bottom up. Originally called Fused Deposition Modeling (FDM) and invented by the co-founder of Stratasys Inc., S. Scott Crump, the FDM name is trademarked by Stratasys and actually must be called something else (like FFF) to avoid legal issues.

For a hobbyist, it’s a great way to make your ideas come to life at a reasonable cost, especially if you’re making custom-designed components for say electronics. It also works for printing puzzles and other neat things off the internet from websites like Thingiverse where you can download object files and making them yourself at home!

But… Guns???

3D printed gun Liberator. Taken from Forbes.

3D printed gun Liberator. Taken from Forbes.

This question gets asked a lot: can someone use a 3D printer to make weapons, firearms in particular, at home? The short answer: yes.

The long answer: Yes, but it’s not the safest nor most legal thing you could do. It has been done several times, including 2 high-profile designs: the Liberator and the Imura Revolver. The thing is however, when you fire a bullet you’ve got a sudden, intense explosion that is contained normally by steel and other metal components. Now you’re trying to do that with 3D printed plastic, which seems to break at much lower strains than typical injection molded parts. And that’s not all, the US Department of State is cracking down on the legality of these guns as well.

Should you 3D print a gun? I don’t recommend it. Would I 3D print a gun? No. 

My Printer

20 mm x 20 mm x 3 mm square: a Hello World for 3D printers.

I chose the Printrbot Simple Metal because it was reviewed as one of the best budget printers with good accuracy for under $1000. It has a 6″ x 6″ x 6″ print volume, which is a little small, and it prints PLA (polylactic acid). It can also later be upgraded with a heated bed to use ABS (acrylonitrile butadiene styrene) which is stronger but more difficult to print. It comes with an auto-levelling probe that measures the average distance from the extruder end to the print bed, making Z-axis calibration a breeze. Like most 3D printers you still need to put some sort of coating material on your print bed to protect it and to help the first layers of plastic stick to it. I use 8″ wide 3M 2090 blue painter’s tape, which I’ve read helps the plastic stick really well, sometimes almost too well.

It was pretty easy to get started printing with, although the Z-axis threaded rod is kind of bent near the top and the coupling came loose during shipping so I had to tighten it up. Other than that, I printed some flat squares and cubes and measured that it was accurate to 1/10th of a millimetre or less in X, Y, and Z (when printing things taller than say 3 mm high). It’s accurate enough for me. 

Okay, that was a low blow.

Due to its great accuracy and potential but small size, I’m going to name mine the Fullmetal Alchemist. The only thing it can’t do is bring its dead mom back to life.


One of the puzzle pieces, and my general printing settings in Cura.

One of the puzzle pieces, and my general printing settings in Cura.

So let’s say you’ve got a wonderful design in CAD. Now how do you get the printer to spit it out? There are programs that will “slice” your model or break it down into flat discrete layers that can be printed by the 3D printer. Luckily for me, Printrbot’s machines can work with Cura, a program developed by Ultimaker who also make their own printers. I haven’t tried other software yet, but Cura can slice and change all sorts of model settings on the fly, from fill volume (you normally print somewhat hollow to save material) to various ways of adding support material around or underneath the part for easier separation. It can even show you what the part will look like layer-by-layer, and also the toolpath that your extruder head will travel.

Precision Prints

Designed by Stewart Coffin.

Designed by Stewart Coffin, as seen on Instructables.

I wanted something fun to play with To test the capabilities and accuracy of the printer, I found an wooden interlocking cube puzzle on Instructables (the second one), drew up some parts in CAD, and printed them. I added some chamfers because I thought they looked cool for ease of assembly, and I was so excited I improperly dimensioned the first piece: I made the height 1.5 mm shorter than the X and Y dimensions.

“That doesn’t look square,” I thought. It wasn’t.

I only lost an hour on that first one, but I still keep the failed print as a reminder: if you’re going to arbitrarily pick a number for a dimension you’re going to reuse, remember it for more than 8 seconds before forgetting.  I probably got distracted by KanColle. It’s just that an event is coming up, and I was LSCing, and there’s a mini-event where you catch fish and stuff, and I need to level my cranes for their Kai Ni…

Here’s a video of it printing the ill-fated part above. There is some rapid zig-zagging motion when printing the top chamfers of these cubes, which I probably shouldn’t be making the printer do. The rapid motion has to do with the layer and print settings I used in Cura. Still working on figuring out why exactly it happens and how to avoid it, but for now enjoy!

But lo and behold, after the last print finished, I was able to solve the puzzle and fit the pieces together in minutes! Not that I spent hours trying to solve it before the last print was finished without success or anything. The cube measures about 52.5 mm in each direction. Thanks to the tolerances of the plastic prints, they stick together a lot better than the wood they were intended to be made of. Actually, they hold together a lot better than they should. Is this cheating? Tehe~ ♥

See the lightbox below for the photos:

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