Objective: 

Learn how to use the Bounding Box 2D Nesting block (image below) to layout and Slice parts on a build plate.

If you would like a deeper look into the workflow or would like to follow along through the steps below you can find the nTop file here:  nTop File - How to use Bounding Box 2D Nesting

Applies to:

• Additive manufacturing

Procedure: 

1. Select the part to layout

To nest objects in a bounding box, we can start with a Surface Mesh or an Implicit Body. The Surface Mesh tends to slice faster for two main reasons, the Object is already discretized and the Field is generally cleaner; in a lot of scenarios, we already have a Surface Mesh of our part due to the desire to evaluate performance using FEA/CFD. This example will show the workflow with both.

 

 

2. Define desired unit count 

Use the Sequence from Bounds and Scale Object blocks to define the desired unit count. 

• • Add a Sequence from Bounds block
    • Set the Start to 1
    • Set the End to 1
    • Set the Count to your desired count for the build plate.
  • Add a Scale Object block (or Scale Body if using an Implicit)
    • Set the Object as your mesh (or part)
    • Insert the Sequence from Bounds block into the Factor input
    • Insert the Centroid from the Imported Mesh (or Body) into the Scale Point input

The parts are overlayed on one another and a List of Objects is created. As seen in the red boxes below, we have a List of 16 bodies. The List will be carried through for the rest of the workflow.

 

3. Slice the list of Objects

• Add a Slice Mesh (or Slice Body) block
  • Input the Scale Object (or Scale Body) block from Step 2. 
  • Set your layer height

Since we are using the Bounding Box 2D Nesting Block in the next step we do not need to select Include negative Z or define a Frame.

4. Nest and Layout Part(s) on Build Plate

4a. Nest Part(s) in Build Volume

Add the Bounding Box 2D Nesting block and define the various nesting parameters; Build Volume, Part to Part Offset, Platform Offset, and Perimeter Offset.

The Bounding boxes input automatically includes an empty List. Delete this List and input the Slice Mesh (or Slice Body) from the previous step. 

 

The additional Inputs for the Bounding Box 2D Nesting are Build Volume, Part to Part Offset, Platform Offset, and Perimeter Offset. 

Build Volume:
You can choose between our current List of EOS/Renishaw/RenAM build volumes (found under the Additive Manufacturing tab) or define your own bounding box for a build volume.

Part to Part Offset, Platform Offset, and Perimeter Offset:
Have default values and define the spacing between the Parts as well as the offsets from the plate and exterior of the select Build Volume.

4b. Layout Part on Build Plate

• • Add a Transform Object block
    • Insert the Slice Mesh (or Slice Body) block from Step 3 for the Object input (red line below)
    • Insert the Bounding Box 2D Nesting block from Step 4a into the Transform input (blue line below)

It is important to note that any parts that do not fit on the build plate are currently repositioned outside the defined build volume which is seen in light blue above. At the moment they have to be manually "trimmed" off (Step 5).

5. Trim slice stack to isolate parts within the build volume

• • Add a Trim Slice Stack block
    • Slice Stack: Insert the Transform Object block from Step 4b
    • Trimming Body: Add a Box from Corners block 
      • Open up the Properties of the part in the Build Volume input (in the Bounding Box 2D Nesting block) and extract the Max Point and Min Point chips
      • Insert the Property chips into the Box from Corners block
    • Slices to Remain: Inside
    • Feature Tolerance: as desired

The final output is a Sliced list of all the parts that fit on the Built Plate Volume and meet the desired constraints. In the example shown, 9 of the 16 bodies are able to fit on the build plate. Exploration of various Build Volumes is easy to achieve by filtering through the current options available as seen in the image directly below with the Build Volume options.

By interchanging the Build Volume in the Bounding Box 2D Nest block (Step 4a) and the Max Point and Min Point volumes in the Trimming Body (Step 5) all 16 units are able to fit on the build plate.

You have now completed how to use the Bounding Box 2D Nest Block to arrange parts in preparation for an additive build.

Download the Example file:

• nTop File - How to use Bounding Box 2D Nesting

More on this topic:

• How to use Minimum Height Orientation
• How to use Minimum Support Orientations
• How to use Angle Field to visualize overhang angles