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How to Cut STL Files for Smaller Printers

How to Cut STL Files for Smaller Printers

Sometimes, 3D printing large parts can be a challenge. Regardless of whether you just want to step up your model or you want to bring it to a 1:1 life-size, it is important to split and trim your models or STL files when making 3D prints that are larger than your build plate.

Instead of scaling down your project, you can divide it into independent portions that can be put together afterward. Breaking up large models is a crucial skill to learn when it comes to 3D printing.

Instead of being deterred by the limitations presented by smaller build plates, we could split models down into smaller portions and then glue them back together. This can be done with design software or directly within our slicers, albeit it does require some expertise.

How to Split an STL File for 3D Printing

Learn how to split your STL file of a 3D model using the simple steps that have been outlined below!

  1. Finding readily-split files

When browsing for your preferred scale model online, opt for one that is readily split or can be divided easily. Many designers upload these alternate versions, especially when they know that most printers aren't big enough to print it all in one go.

A split model is an uploaded set of STLs that are ready to be printed part by part instead of at once. Most of these models fit together perfectly when they are assembled, while some of them are even cut to pieces because it makes it easier to print irrespective of the size of your printer.

These types of files would save you a lot of time since you don't have to split the files yourself.

  1. Separate multipart STLs

Some STLs that have been uploaded to the internet have been modeled as multipart STLs. These files are necessary for multicolor or multi-material printing, but they can also be used to create big models.

  1. Slic3r: a slicing platform capable of dividing multipart STL files into their constituent parts, can be used for this operation.
  2. First, open the multipart STL in Slic3r.
  3. Select the "Split" option from the toolbar above, and your multipart STL will be split into numerous STLs.
  4. After eliminating the others, you can now slice each portion one by one or export each part as its own little, printable STL.
  5. Autodesk Meshmixer: this is another program you may use to separate these multipart STLs. All you have to do is use the "Separate Shells" command. It can break down multipart STLs into single-part STLs.
  6.  Simply open your multipart STL on the page, and some information about the STL will be displayed.
  7. A checklist will appear, allowing you to select the STL files you require.
  8. To create your single-part STL, click "Download." Keep in mind that you can only download one part at a time, as selecting several parts will combine them into a single STL.
  9. Split your files with plane cut

You can split the STL file manually if the model you wish to print isn't available in many parts. A standard feature called plane cut, which is included in most mainstream (Computer-Aided Design) CAD applications, here's how to go about it, using some popular software:

  1. Autodesk Meshmixer: This software that allows you to have a lot more control over how you separate and split your 3D printing files. Here is a step-by-step guide to successfully cut STL models in Meshmixer;
  2. To begin, open the Meshmixer platform and import your model.
  3. Select “Edit” & hit “Plane Cut”
  4. To find the Plane you wish to cut, rotate the screen.
  5. To cut the model in the required area, click and drag.
  6. Change the "Cut Type" to "Slice" to avoid wasting any of the models, then click "Accept."
  7. Your model is now separated
  8. To break the model up, go back to "Edit" and pick "Separate Shells."

Another amazing feature of Meshmixer is the ability to add alignment pins to your split models that fit between two sections like a plug.

  1. Windows 3D builder: One of the simplest ways to break up an STL file and cut it into multiple parts is to use a 3D Builder. Most Windows computers come with it pre-installed, and it can also be downloaded for free from the Microsoft Store. The software has a slick, responsive UI with simple features that even beginners would find easy to learn. To split a model in 3D Builder;
  2. Simply choose a model.
  3. In the Taskbar above, choose "Edit," then "Split."
  4. The rotation gyroscopes would then be used to place the cutting plane anywhere you wish.
  5. When you're finished, click "Keep Both" and then "Split" to divide the model in half.
  6. Last but not least, save it as an STL file.

For both beginners and specialists in 3D printing, 3D Builder makes the splitting process a breeze. The cutting plane is simple to use, and you may use it as your go-to model slicer like hundreds of others have.

  1. Slic3r: Slic3r's cutting function is a rapid cutting tool, however, it only works in the XY plane. You can drag the cutting plane along the Z-axis by selecting the "Cut" command.

Even though it is an easy operation, make sure to cut the model intelligently and consider the following factors: First, make sure the slice will permit printing the models easily so that you may minimize or delete supports while printing. Also, attempt to find the slicing plane in the model where the seam won't be visible once it's glued together.

Once the pieces have been printed, use an appropriate adhesive to link them together to form a single model. The adhesive you apply will determine the model's strength. If you're concerned about aligning those disjointed portions, there's an easy fix for that as well.

What to Do About Disjointed Parts: How to Create Keys and Joints

To handle 3D drawings, most major CAD software allows you to use simple forms. You could model pegs and holes in your pieces to make assembly easier, which will help them align and fit together when the time comes.

Designing a strategically located 2 mm hole in your parts, then introducing a short length of filament to align them before gluing them together is another popular approach for attaching parts. However, if you want a more durable item, you should use traditional joints and keys, such as those used in woodworking.

Other materials, such as metal rods, screws, or bolts, can also be used to fasten parts, especially when the connections require extra strength. If you're making props or functioning parts, this might be necessary.

  1. Modify with CAD or 3D Modeling Software

When you have access to the model's raw files rather than just the STL, you can alter it with a variety of CAD and 3D modeling programs.

Some designers include the original files, which the public can access. These are typical models that can be customized. You can also look at various CAD file download sites for a steady stream of original design files.

The main issue here is file compatibility between different CAD systems. Not all apps can edit every file type. If at all feasible, look for a STEP (Standard for the Exchange of Product model data) or (Initial Graphics Exchange) IGS file of the model you're looking for, as these can be opened with most CAD systems.

  1. Split your Model with Fusion 360

To split a model in Fusion 360;

  • Start by sketching where you want to separate it.
  • Change the Operation to "New Body" after extruding the drawing towards the inside of your model.
  • With the Splitting Tool selected, press the "Split Body" button and choose the model to split the two pieces apart.

Another technique to split a model in Fusion 360 is to;

  • Use the "Construct" area of your toolbar to create an Offset Plane on your model
  • Move the Plane to where you want to split the object.
  • Select the Plane to cut by clicking the "Split Body" button in the toolbar. A Plane can be used on each face of your model.
  1. Split your Model in Cura

To split a model in Cura;

  • First, install the "Mesh Tools" plug-in from the Cura Marketplace.
  • After you've downloaded it, simply choose your model.
  • Go to the Extensions menu, and look for Mesh Tools there.
  • Finally, select "Split model into parts" to divide your model into two pieces.

The approach Cura uses to divide apart a model is pretty simple. The Mesh Tools plug-in was not required in previous versions of this slicing program. You simply had to right-click on the model to bring up the option to split it.

Cura, unfortunately, does not use advanced cutting techniques in cutting models. For more complex part splitting, you can make use of Fusion 360 or Meshmixer.

  1. Additional Tips for Fastening and Finishing

After you've split, printed, and built your model, it's time to add the finishing touches to it. To remove the extra glue that sticks out of the bonded area, sanding can be used. Also, any little misalignment created by gluing the model together can be smoothed out this way.

If there are gaps between the divided portions, a 3D pen can be used to melt the same filament used in the printing of the model and run the melted filament material through the gaps. Putty, fillers, and other adhesives can be used instead if you plan to paint the model.


Cutting or slicing STL files is not a difficult procedure. With the above steps, you

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