Breaking Down Large 3D Prints into Multiple Parts for Printing

Breaking Down Large 3D Prints into Multiple Parts for Printing

When 3D printing, one common issue that arises is trying to print a model that is too large to fit on your printer’s build plate. Rather than scaling down the model and losing detail, there is a smart workaround – break your print into multiple interlocking parts that you can assemble after printing.

In this comprehensive guide, we’ll cover when and why to split up your prints, how to properly divide your models using 3D modeling software, tips for alignment and assembly, and alternative methods if breaking apart your model won’t work.

When To Split Up Your Model

3D design interface showing a red figurine model encased in a selection box on Tinkercad.

The most obvious case for splitting a 3D print into parts is when your print volume is too small. If your printer has a 6-inch cubed build area, and your model is 8 inches tall, it’s simply not going to fit.

Rather than buying a bigger printer, see if you can cleverly break apart your model along a logical seam. This not only allows larger prints but is often necessary for prints with overhangs and extensions that require lots of dense support material during printing. Removing these overhangs by splitting the model can result in higher print quality.

How To Divide Your Model

Most 3D modeling software like Tinkercad or FreeCAD allows you to accurately cut your model into segments that interlock together.

Here is the basic process:

  1. Import your model into your software.
  2. Select where you want to make your cut using primitives like planes or cylinders. Align them on logical break points in the model’s geometry.
  3. Use boolean tools to split/cut the model along those planes or intersections, creating two separate bodies.
  4. Add alignment features like small dowel pins, crosshead screws, or notches so the two halves align precisely during assembly.

For example, if printing a large cosplay helmet, you might split it vertically right down the middle, front to back. Then add a couple of alignment pegs on the left half, and holes on the right half. This interlocking system ensures proper mating of the two pieces.

Tinkercad screen showing a red figurine model with its torso and head separated from the legs on the workplane.
Helmet model divided into left and right parts

Tips For Assembly

When breaking a model into multiple parts, consider:

  • Mating Surfaces – Flat mating surfaces with lots of contact points will stabilize the bonded pieces. Interlocks also help.
  • Adhesives – Cyanoacrylate “super glue” works very well bonding PLA and ABS prints. Epoxy is stronger for more load-bearing builds.
  • Reinforcements – In addition to adhesives, you can use small screws, plastic welds, pins and mechanical fasteners to further strengthen joints.

Also, test fit the individual printed parts together before bonding to check for accuracy of fit. Sand down any imperfections on the mating surfaces.

Lightly scuffing the surfaces and pre-warming ABS prints with a heat gun allows the adhesive to penetrate better. Apply adhesive sparingly along the center of flat mating surfaces rather than around the edges. This prevents squeeze-out.

Two separate parts of a red figurine model displayed on the Tinkercad workplane, indicating a division for 3D printing.
Helmet model gluing process

What If Dividing Isn’t Practical?

For some models, splitting them into parts just isn’t feasible while retaining integrity of the end product. For example, intricate channels or inner voids would be difficult to align across segments without losing dimensional accuracy.

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In these cases, you have two options:

1. Scale Down Uniformly – Maybe by printing your model at 90% scale everything fits. Just beware loss of detail when scaling too far down.

2. Print In Sections – Rather than dividing logically across mate-able surfaces, you can print vertical or horizontal cross-sections of the model in segments, then bond stacks them together after printing. Alignment may be more difficult but not impossible.

Enable Bigger and Better Prints

Dividing larger prints into smaller segments requires some extra modeling effort, but pays off when you can fabricate accurate, intricate models beyond normal print volume constraints.

Carefully plan out your segmentation strategy, interlocks, and bonding mechanisms before breaking apart that giant model for your gaming diorama or Iron Man suit. Assembly may be required, but the end product will be monumentally awesome!

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