How to Split Large 3D Prints for Better Quality and Assembly

A common challenge when using 3D printing is printing large or complex models that don't fit into the printer's build volume; smaller parts can be printed with greater detail because a smaller print area reduces the risk of warping or misalignment while reducing the number of supports. This guide will walk you through the process of splitting a 3D part.

Source: https://store.trimech.com/blog/three-tips-when-splitting-a-large-part-for-3d-printing

Step 1: Analyze the Model and Determine Split Points

The first step in splitting a model is to understand the geometry and structure of the object. Look for areas that can be easily separated without affecting the final result. These may include:

Natural Breaks: Identify joints, seams, or sections that can be split without affecting the integrity of the final print. For example, models with arms, legs, or removable parts are great for splitting.

Plane: Cut along a plane whenever possible, as this will ensure that the split is less noticeable and easier to glue together.

Functional Parts: If your model has parts that must move or connect, consider splitting in a way that allows for easy assembly using screws or connectors.

Step 2: Split the Model Using 3D Modeling Software

Once you've determined where to split your model, you'll need a 3D modeling software that allows you to cut or split the object. Here we take Meshmixer as an example. Meshmixer is a free 3D modeling and repair software provided by Autodesk, designed for editing, optimizing and preparing 3D printing models. It is lightweight and feature-rich, suitable for beginners and professional users to quickly model, repair and improve existing 3D models.

Steps to split a model in Meshmixer

1. Import the model

Open Meshmixer, click the "Import" button in the upper left corner, and import the model file (such as STL, OBJ file) to be split into the workspace.

2. Select the cutting tool

In the toolbar on the left, select the "Edit" menu and then click the "Plane Cut" tool. This tool can create a plane to cut the model.

3. Position the cutting plane

Once the "Plane Cut" tool is selected, a cutting plane and three control handles will appear. Drag the plane's arrow to adjust its position, or rotate the plane to align it with the split position of the model. You can also adjust the angle and position of the plane by entering a numerical value to ensure the cutting position is accurate.

Source: https://weareprintlab.com/blog/10-steps-to-getting-started-with-meshmixer-for-3d-printing/

4. Perform the cut

Select the type of cut in the settings panel on the right side of the screen. The "Keep Both" option will keep both parts after the cut instead of deleting one. Click "Accept" to confirm the cut and the model will be divided into two parts.

5. Export each part

After the cut is completed, each part will become a separate object. Right-click each part, select "Export" and export them separately as STL files to facilitate the subsequent printing process.

Step 3: Use keys to ensure accurate alignment

After splitting the model, to make assembly easier and ensure a precise fit, you can add small pins or nails (called "keys") along the split edges of each part. These keys interlock with matching holes (keyways) on adjacent parts to help align and secure them. By using keying, you can minimize visible seams and improve the overall structural stability of the model.

Source: https://www.reddit.com/r/3Dprinting/comments/aua16a/proper_way_to_print_pins_2mm_diameter/

For example, you can add small cylindrical or rectangular nails on one part and add corresponding holes on the adjacent part, keeping a gap of about 0.1-0.2 mm between the key and the hole to ensure smooth assembly. During assembly, these keys and keyways lock the parts together, making gluing or reinforcement easier and more reliable.

Step 4: Assemble the parts

Once all the parts have been printed, it’s time to assemble them. You may need to use a strong adhesive like super glue or epoxy to glue the parts together, please refer to this article for details.

Splitting 3D parts is a must-have skill for anyone who wants to print large or complex models. By following the steps above, you can maximize your chances of having your parts fit perfectly. If you need help with 3D printing or have a project that requires complex 3D printing, feel free to explore the 3D printing services provided by JLC3DP, we specialize in high-quality printing and can help you print complex models.