Designing for Large Format 3D Prints: Essential Guidelines for Success

  • July 18, 2023

When it comes to large format additive manufacturing, such as Massivit 3D, Big Rep, and WASP, designing objects requires careful consideration and adherence to specific guidelines. In this comprehensive article, I, Paulina Chodura, an experienced application engineer in the 3D printing industry, have compiled a set of simple design guidelines to ensure optimal results for your large-format 3D prints.

Mesh Checklist:

  1. Closed Model: One of the challenges in 3D printing is dealing with holes in the meshes. Ensuring your model is watertight is crucial. Imagine pouring water into your model – if it would leak out, your model is considered “leaky” and not watertight. Non-manifold 3D objects will not slice correctly, so it’s important to repair any non-manifold models before printing.

Many slicers nowadays have the option to “fix” holes automatically. However, for precise results, it’s better to close the holes before slicing. This is especially important when it comes to holes on curved surfaces, scanned objects, or artistic pieces. While automatic fixing of holes may be hardly noticeable on small prints, on larger models they can make a big difference and cause additional costs related to post-processing.

  1. Inverted Normals: Uniformity in the polygon’s normal direction is essential. All normals of a 3d model must point outwards to avoid any printing issues. Verify and correct the orientation of normals in your 3d object to ensure a successful print.

Any 3d modeling software has the option to detect and invert the normals automatically.

  1. Unconnected Parts: To optimize material usage and avoid unnecessary costs, it is important to ensure that all elements of your design are smoothly connected to the main body. Avoid creating “free-floating” parts, especially those in the upper parts of the model, as they will require extra supports making them expensive and challenging to print.
flaoting part in a 3d model
Floating parts can be tricky to spot in 3d models but are important for the success of your print

If your model contains floating parts, consider extracting them and printing all parts separately. While printing large objects, any unnecessary unconnected detail can significantly increase the printing cost and time.

  1. Internal Geometry: While it is acceptable to have internal faces in your design, it is recommended to perform a thorough cleaning of the 3D object if unnecessary internal geometry is present. Removing internal geometry can save printing time, reduce material consumption, and simplify the overall printing process.

Internal faces and walls can unnecessarily complicate your already long print and lead to failures. The process of cleaning the 3d mesh can sometimes be very complex and requires a bit of patience.

  1. Wall Thickness and Wall-to-Wall Distance: Maintaining an appropriate wall thickness is crucial for successful large-format 3D printing. Ensure that the wall thickness is at least twice the diameter of the selected nozzle tip. Additionally, consider the printing mode when designing thin areas on your 3D model. Inadequate wall thickness in specific areas may result in missing details in the tool path.
wall thickness measurment of a 3d model

In large-format 3d printing, the nozzle diameters can be significantly bigger than their desktop counterparts. A variety of materials used for large-format printing often calls for complex composites that require bigger extraction exits. Consider the material and the technology while designing your piece and ensure proper wall thickness and spacing within your design.

Printing Parameters:

  1. Printing Orientation: Properly orienting your model for printing can significantly impact material usage, print time, and overall print quality. Avoid incorrect orientations that require excessive support structures. Additionally, consider the resolution or print quality required for your design.
printing orientations of a 3d model
When selecting a 3d model, the printing orientation is important for the quality and success of the print

Incorrect print orientation can lead to warping and inaccuracy in many printing technologies. Already at the design stage, your 3d piece should take into account the way it’s going to be printed for maximum efficiency and the best quality of details.

  1. Difficult Angles: When dealing with narrow models, be cautious of negative angles, as they can lead to collapses during the printing process. Positive angles generally print without difficulty, but if they are too narrow, they may be susceptible to lifting up.
Red areas highlight the negative (hard to print) angles in the 3d model (Cura Slicer)
Red areas highlight the negative (hard to print) angles in the 3d model (Cura Slicer)

For most technologies, the negative angles range from 45° to 60°. Some 3d printing technologies like SLS do not need to take into account the negative angles. The printing powder provides a natural support. But most large format technologies still use the classic extrusion printing mode which is prone to sagging and dripping on hard angles.

  1. Mesh Resolution: Large format 3D prints necessitate high-resolution meshes. Ensure that your model is exported from CAD software with an appropriate level of mesh density. Avoid faceted surfaces, as low-resolution models printed in large format may exhibit undesirable facets and artifacts.
3d printed model with visbile edges between polygons (due to low resolution of the model)
3d printed model with visible edges between polygons (due to the low resolution of the model)

For a typical model of above 1 meter height, a mesh resolution of up to 1 million polygons is recommended to achieve a smooth look. Lower resolution meshes usually take longer to print because the nozzle “slows down” on sharper visible polygon edges.

  1. Flat Surfaces: Pay attention to flat surfaces in your design and take into account the accuracy of a 3d printing technology you’re designing for. Some technologies (like gel printing) require ensuring that straight long walls are supported, level, and properly aligned. Any inaccuracies or misalignments can affect the overall quality and appearance of the final print.
Visible warping on a printed 3d model
Visible warping on a printed 3d model (Source)

Some technologies can have issues with printing large flat surfaces. There can be graining or warping on these planes. To avoid them, make sure your wall thickness is accurate and that your walls are securely supported.

  1. Mesh Smoothness: Strive for smooth surfaces in your 3D model. Refine and optimize the geometry to achieve the desired smoothness, eliminating any unwanted irregularities or roughness that may be visible in the final print.

Grainy or textured models are a great use of 3d printing technologies. However, the textures can significantly increase printing time. Depending on the final finishing of your project, decide whether the model should be printed smoothly and finished in a workshop or if it’s worth investing a bit more time in the printing process.

  1. Splitting the model: Consider the possibility of cutting or splitting your model if necessary. Large format 3D printing may require dividing the design into smaller printable parts and reassembling them post-printing. Plan and incorporate suitable joint designs and alignment features for a seamless assembly process.
When splitting the model make sure to consider the printing orientation as well as the post process
When splitting the model make sure to consider the printing orientation as well as the post process (don’t cut on important details)

If you plan to print your model in parts you should consider it already at the design stage. Separating the model into parts should be discussed with the post-processing team to avoid issues at later stages of assembly. Making small markings on your model or creating clear joints can be essential to a successful large-format project.

  1. Simultaneous Printing: For larger projects, simultaneous printing of multiple parts can be a time-efficient approach. Optimize the arrangement of multiple objects within the printing volume to maximize efficiency and minimize printing time.
Two different 3D-printed statues of a similar height/volume
Two different 3D-printed statues of a similar height/volume

If you have more than one printer available or a printer capable of printing multiple objects at the same time (BJ,SLS,SLA), you can consider printing some parts together. In these scenarios, it’s often recommended that the parts are grouped according to their volume (similar height is often more important than width to save printing time).

By following these design guidelines, you can enhance your success rate in large-format 3D printing and achieve outstanding results. Remember to thoroughly review and test your design before initiating the printing process to ensure a smooth and successful printing experience.

About the Author: Paulina Oliwia Chodura is a skilled 3D modeling specialist who offers her expertise to scenic fabricators and 3D printing bureaus. With a meticulous approach and a talent for transforming concepts into tangible creations, she excels in fixing and creating 3D files (.stl, .step, .skp) based on sketches or photographs. Whether utilizing Zbrush, Rhino, or Fusion 360, Paulina is dedicated to delivering outstanding results and bringing designs to life. For all your 3D modeling needs, don’t hesitate to reach out to her!