Optimizing 3D prints and getting the most out of your 3D printer

Spending time optimizing your 3d model before printing can greatly improve overall quality while reducing print time too. The easiest thing you can do is to thoughtfully orient your model on the print bed to minimize the amount of support needed. Also, keep in mind that most consumer 3D printers do not have the same “resolution" on each of the 3 axes, orienting your part prudently will make your print look much better. For prints that do not have ideal orientations sometimes breaking the model into parts and fusing them together afterwards is the better option. Most of the time there is no “correct” answer and some models simply aren’t suited for FDM printers, however the following techniques will ensure you use your printer to the best of its capabilities.

Orienting to minimize support material

Since the 3D printer builds each layer on top of the previous one, support material is 3D printed alongside the model so that the printer has something to print on when it reaches overhangs or features floating in mid-air. Support material takes extra time to print as well as needs to be removed after the print is complete. Ideally no support material is used. One simple way to avoid support material is to rotate your piece so that overhangs become bases.

Another important aspect to consider when orienting your parts is to start with a flat area that can adhere to the platform. For example, printing a sphere is problematic because the first layer printed would be a virtual point, which is not stable or able to provide grip to stay in place. Most likely, the printer will accidentally knock the print off the print bed during your print. Moreover, it would require a significant amount of support material and that means increased print time. If you can’t rotate the piece so that it has a solid base and minimum amount of overhangs than your next best option is cutting the model into pieces and fusing them together afterwards. Figuring out where and how to cut the model will be determined by what details you'd like to preserve.

Orienting to optimize quality

Most consumer 3D printers are FDM type printers, meaning they squeeze out melted plastic layer by layer. By nature of the process the smallest printable feature size is therefore limited by the nozzle diameter. Imagine drawing two faces on a small piece of paper. One face you use a sharpened pencil and the other you use a thick felt tip marker. No matter how precisely you draw with the marker the small features of the face are blurred and bleed together compared to the pencil’s fine lines. The tip of the marker is larger than the feature’s of the face. Carry this metaphor over to the 3D printer: the printer’s nozzle is large compared to the fine movements the motors are capable of. So although all three axis motors can move at the same resolution (i.e. step size) the axis perpendicular to the nozzle suffer from the nozzle's relatively large size (around 0.4mm on consumer FDM printers). When orienting models, keep this in mind to make the most of you’re printer’s fine motor control and choosing which model details are important.

The examples above show how the heart on the top surface of the gray cube did not print clearly while the ones on the side did. This is a symptom of the nozzle diameter being too large and was addressed by simply printing the model larger because a seam was unacceptable. The next section explores a technique if seam lines are acceptable.

Breaking up a model into parts

If you own a 3D printer you’ll find yourself wanting to split a model into pieces at some point. This allows you to print models larger than your printer's printable area. Moreover, less plastic means less warping and shrinking which means higher quality prints. Below I’ve create a few videos showing you the essentials to splitting a 3D model into pieces. Blender is a free open-source professional 3D computer graphics software for Mac and PC and can be downloaded here: http://www.blender.org/download/

If you've never used Blender or any 3D modeling software, I'd recommend this video to quickly get up to speed on how to navigate in 3D space: https://www.youtube.com/watch?v=xT2mtoDnSzM 

In the first video, we import a .STL file, separate the geometry we want out of the model and fix the leftover hole.

Steps in video above:

  • Activate the STL add-on and import your model
  • Switch into ‘Edit Mode’ by using the tab key (e.g. or using the menu at the bottom left)
  • Switch into wireframe mode with ‘Z’ key. This allows you to select polygons hidden behind other polygons
  • Switch into Persp/Ortho Mode under the ‘View’ menu in the bottom left
  • Switch to a front or side view using the ‘View’ menu in the bottom left (or the number pad if you have one)
  • Activate the box selection mode with the ‘B’ key and box select the geometry you want to separate. Hit ‘ESC’ key to return to edit mode.
  • In ‘Edit Mode’ and with a selection, use the ‘P’ key and select ‘Selection’ to move the selection into its own object
  • Exit ‘Edit Mode’ and go into ‘Object Mode’. Hide the rest of the geometry by clicking the eyeball in the object list on the right.
  • Right click to select the newly separate geometry, and enter ‘Edit Mode’
  • Hit the ‘A’ key to un-select everything, and rotate the camera to find any holes leftover from separating the geometry.
  • In 'Edit Mode' hold 'Option/alt' key and left click on the edge of a hole -- this should select the loop. If it doesn't, Blender can't find a loop and you'll have to do it manually by holding 'Control' and right click on each edge.
  • Once complete, use 'F' key to fill the area and plug the hole.
  • Export the file as an STL and print it!

In the second video, we define an area where the model will be cut and do what’s called a ‘boolean operation.' Boolean operations are sometimes finicky and are one reason why having manifold geometry is important. The first part of the video is closing the holes in the model before doing the boolean operation.

Steps in video above:

  • Hide the unneeded objects by clicking the 'eye' in the object list
  • In 'Edit Mode' hold 'Option/alt' key and left click on the edge of a hole -- this should select the loop. If it doesn't, Blender can't find a loop and you'll have to do it manually by holding 'Control' and right click on each edge.
  • Once complete, use 'F' key to fill the area and plug the hole.
  • Exit 'Edit Mode' into 'Object Mode' and left click where you'd like to create the cube
  • Use 'Shift-A' to add a Mesh > Cube
  • Move the cube with 'G' to where you're planning to remove the material. You can lock movement to the x, y, or z axis by pressing the corresponding letter (e.g. 'G' + 'X' ; or 'G' + 'Y')
  • Scale the cube in the same way using the 'S' key
  • Duplicate the cube using 'Shift-D' and using x, y, or z to lock it. Align the cube edges.
  • Right click to select the model. Watch video above at 1:55 for how to add a boolean modifier
  • Right click the model you wish to export and use the menus: File > Export > STL

Splitting up a model into parts takes some intuition and creativity and each one is unique. Using the techniques above hopefully you know what to look out for when trying to print things from the internet. Keeping these optimizations in mind  when creating the model will save you a lot of time, material, and headache in the long run too. Happy printing!