Splitting a part bigger than the bed
Where to cut, which joint to use, how much clearance to leave and what to bond with, so the seam neither shows nor becomes the weak point.
5 min read
The bed is 256 × 256 × 256 mm. Anything larger has to be split, and splitting a part well is a design skill rather than a setback: done properly the seam is invisible, and the part ends up stronger than if it had fitted whole, because each half can be oriented the way it prefers.
Where to cut
- 1Along an edge, never across the middle of a visible face. A seam that lands on an edge you already have disappears; across a smooth surface it shows every time.
- 2Through the smallest section. Less joint area means less to bond and less to sand — but be careful, it also means less glue area.
- 3Where the part is not loaded. If you know where the force runs, keep the seam away from it.
- 4So that both halves sit flat on the bed. That is the real prize: zero supports on either, and the best possible surface.
Which joint
| Joint | When | Clearance |
|---|---|---|
| Pins and sockets | The default. Two or three pins align it and add glue area. | 0.2 mm on diameter |
| Tongue and groove | Long straight seams: letters, panels, mouldings. | 0.2 mm per side |
| Dovetail | When it must take tension without relying on glue. | 0.3 mm per side |
| Screw and insert | If the part has to come apart again. | Per insert |
What to bond with
- Cyanoacrylate (superglue) for PLA and PETG: instant, and stronger than the layers. For large-area joints, use the gap-filling grade.
- Two-part epoxy when the joint has to carry load: more open time to position, and it fills the clearance.
- Acetone for ABS only. It dissolves the plastic and genuinely welds the halves; it does nothing on PLA or PETG.
If you would rather not split it yourself, upload it anyway: the configurator will tell you it does not fit. Say in the notes where you would prefer the seam and we will split it — that is modelling work, but on a simple part it is usually a matter of minutes.