This post is going to be an overview “So you want to 3D print a free file from the internet?” guide. I’m going to briefly take you through Thingiverse.com, file set-up with Meshmixer, 3D slicing with Slic3r (to turn the file into linear machine code), and finally printing the file. This all took place at Seattle Makers makerspace, using a Prusia i3+ 3D printer (modified by MyOpen3D).

[I will assume you know the most basic controls of meshmixer and slic3r, but I link to the manuals. I’ll assume you have at least a basic idea of operating a 3D printer, but provide a few bits of advice too. This whole file-prep process can take from 5 minutes to even a few hours depending on the file and your experience level.]

I want to print this frog, the meme It Is Wednesday My Dudes frog. Budgett’s frog, aka Lepidobatrachus laevis looks pretty goofy but also unique.

The first step to printing this funny looking meme frog is either modeling it from scratch yourself, or finding a copy made by somebody else! We’re going to do this the easy way, by searching thingiverse. On Thingiverse.com you can find a huge selection of 3D files available for printing, usually under some version of a Creative Commons license. A Creative Commons license usually carries some or all of the following good-faith obligations like “Attribution Required”, remixing allowed, no retail sale etc. The wiki summary is here.

So we’ll download the file and next open it up in Meshmixer, a free 3D file editing program. This free program is quite powerful if you know how to use it. Since this file is ready to go, we’ll just do a few basic checks on it before turning it into machine code for the 3D printer- Orientation, Alignment, Overhangs, and Supports.

1-ORIENTATION

First, after importing into meshmixer, decide the best model orientation. That means printing it so that most of the model rises up from the printer bed. (The easiest shape to think about this is a pyramid; You want the largest part on bottom and smallest part on top because each filament layer prints upon the previous layer.)

Click “Edit->Transform”. Dragging the colored wedges lets you manually decide the orientation, and moving your cursor further away lets you do units of exactly 5. Alternatively, use “Analysis->Orientation” but this can take a long time for more complex files. It’s best used as a final check, in my personal opinion.

2-ALIGNMENT

This is a quick step, but necessary. Make sure that your file actually touches the bed and isn’t a free-floating ghost. It’ll give you problems later when you generate supports.

(Quick aside- I used the “Plane Cut” option to give the frog a flat belly for a better print, but this isn’t required. Either way, do that step before alignment.)

Click “Edit->Align->Transformation:Transform Only” then Accept. Now your model is grounded to the printer bed!

3-OVERHANGS

Next up is overhangs-An overhang is where you print filament with little to nothing underneath it, which can be risky. 3D filament is printed on top of existing filament, so you need to ensure the overhang angle is not beyond what your machine is capable of or else it’ll instead look like a blob of melted spaghetti, like below. (This graphic is from the UT Austin site.)

Actual Print CAD Model

This is a blurry definition, but if you haven’t 3D printed much, then you won’t yet have a good intuition of what angle your machine can or can’t handle. Try this overhang test file by MeneerMark if you’re curious. The print I’m using can handle >60 degree overhangs, so I’m not worried about this frog print needing support pillars, but Meshmixer can add those automatically or manually.

Click “Analysis->Overhangs”

4-SUPPORTS

We won’t be needing supports for this shape, but it’s good to check each time. It’ll be the last step in this process since it adding supports commits you to this model’s orientation. You’ll have to trust me on this because it looks like the entire chin won’t be supported. In a future post I’ll include details about the art of making supports manually. (Some programs make good automated supports, but this is a free program so we make do.)

After exporting these edits in Meshmixer to ensure a good print (OBJ or STL format), you’ll import it into a 3D slicer program which will turn a 3D file into linear machine code (G-code) for a 3D printer to read.

Slicing a file into machine code with Slic3r

You’re almost there, I promise! Here is the Slic3r manual, you might need it.

First- check that the file connects with the bottom of the plate, or else it’s free-floating and won’t print properly. Then, make sure that you have your 3D print filament settings up to date (in settings). Each spool has a unique diameter within its manufacturing tolerances, and tiny differences (if unaccounted) can lead to over/under extrusion, and a ruined 3D print!

Once you’ve checked your settings, and deciding upon a good infill % (I used 30% for this model), click “Slic3” and let it calculate the machine code file. It should look like this.

Once you have the g-code file, check that (1) it still makes contact with the bed, and (2) that it has the hexagonal infill you desire. Like this.

Next, save your g-code file with a unique and descriptive name so that you can find it easily. Include information like Filament Color/Type, Infill %, and File Author (in this case, joepotato420 from thingiverse).

Save this file on your SD card as well as in a safe second location. Don’t lose your hard work now, it sucks.

ACTUALLY PRINTING

Let’s get started with the actual print now that we’ve done all of our prep work! It should take about 30 minutes to print. The machine I’m using takes SD cards to minimize opportunities for failure via USB link. There are a few quick checks, but overall be sure to watch the print in case you have to do an emergency stop.

Make sure that your glass slide is level and thinly/evenly coated properly (I’ve used vinyl-based hairspray as a good surface coat). Put your printer head safely in the origin corner, and out of the way any binder clips. Now you’re ready to hit print!

Push the button! Select your file, hit print, and watch while the bed and nozzle heat up.

After the print is done, gently take the glass print bed off the heating bed and let it cool. Then to remove the print, try to use light prying pressure with a thin metal frosting spatula on the overhangs, or lightly use a vinyl hammer on multiple strong points of the model so it all comes off at once, in one piece.

And there you have it! I tried to address the biggest nuances that you often only hear as informal advice but without losing you in the weeds. You can now take a free 3D model through the entire process of set-up, translating into g-code, and printing, all with an eye of troubleshooting along the way.