How to Split a Large Model for 3D Printing

Our Bambu Lab printers have a build volume of 256 × 256 × 256 mm. If your part exceeds this in any dimension, it needs to be split into sections for printing and assembled afterwards. Done thoughtfully, split prints can be almost indistinguishable from a single print. Done badly, the joints are weak and misaligned.

This guide covers how to split models sensibly and join them reliably.

Choose where to cut carefully

The cut location is the most important decision. Good split locations have these characteristics:

• Away from stress concentration points — don't cut across a narrow section or near a bolt hole where forces concentrate
• At a naturally flat or geometric transition — splits at a right angle or regular feature are easy to align
• Where the joint will be hidden or accessible — plan for how the joint will look and whether you need to access it for assembly
• Not at a critical dimension — if a specific surface needs to be continuous and accurate, the split should be elsewhere

Design registration features

Before splitting, add features that help the two halves align correctly:

• Alignment pins and holes — dowel pins of 3–5 mm diameter, with 0.3 mm clearance per side. Print the holes in both halves, glue pins in one side.
• Tongue and groove joints — a male/female feature on the cut face that keys the two halves together
• Puzzle-cut edges — interlocking profiles that resist pulling apart and provide self-location

At minimum, include two alignment features per split face, spaced as far apart as possible — one feature leaves rotational freedom; two lock the alignment completely.

How to split a model in Fusion 360

1. Create a construction plane at your split location (Construct → Plane at given point)
2. Use Modify → Split Body, selecting the plane you created
3. This produces two separate bodies
4. Design alignment features on both halves at the split face
5. Export each body as a separate STL file

How to split in free tools

Meshmixer (free):

1. Import your STL
2. Use Edit → Plane Cut to cut at your chosen position
3. Export each half separately

PrusaSlicer / Bambu Studio:

Some slicers include a "cut" function for splitting objects within the slicer interface, without requiring CAD software. This is the simplest approach if you don't have access to CAD tools but lack alignment feature design capability.

Joining the sections

For most structural applications:

• Cyanoacrylate (super glue) — quick and strong for static joints. Add accelerator for faster cure. Works well on PETG to PETG joints.
• Epoxy — stronger and fills gaps. Use for heavier parts or where the joint needs to be loadbearing. 5-minute epoxy works for most applications; 24-hour epoxy for maximum strength.
• Mechanical fasteners — bolts or screws through printed bosses with heat-set inserts give disassembleable joints and maximum strength. Design the joint for this from the outset.
• Solvent welding — specific solvents can fuse PETG to itself. This is more advanced and requires care with fumes.

A note on ordering split parts

When ordering split parts using our quote tool, upload each STL file separately — the tool handles multiple files per order. Set the same quality level for both halves to ensure consistent layer lines (important for aesthetic splits). Use the order notes field to let us know the parts should be printed together as they belong to the same assembly.