Preparing for Production

Overview

In this practical lesson, students finalise their CAD model and prepare it for potential 3D printing. Building on earlier modelling and design-criteria work, they inspect scale, wall thickness, overhangs and orientation, correct errors, and export an appropriate production file such as an STL.

Learning intentions

Students will:

• inspect a CAD model for errors that may affect production
• explain how scale, wall thickness, overhangs and orientation influence 3D printing
• make justified adjustments to improve a model’s print readiness
• export and label an appropriate file for the next production stage

Success criteria

• I can use a checklist to inspect my CAD model.
• I can identify and correct at least one production problem.
• I can justify my decisions about scale, wall thickness and orientation.
• I can export a correctly named file in an appropriate format and record the settings used.

Curriculum links

• Design and Technologies: analysing needs and opportunities, and selecting suitable materials, systems, tools and equipment for designed solutions.
• Design and Technologies: analysing how material and component properties combine to create designed solutions.
• Design and Technologies: generating, testing, iterating and communicating design ideas using digital tools.
• Design and Technologies: developing design criteria, including sustainability, to evaluate design ideas and processes.

Lesson structure (60 minutes)

1. 0–5 min · Hook and learning intention. Teacher displays two examples of a successful and failed 3D print using the production-readiness introduction slides, then asks, “How could a model look correct on screen but fail during printing?” Students discuss one possible cause with a partner and review the learning intentions.

2. 5–15 min · Direct instruction and demonstration. Teacher demonstrates the CAD inspection workflow using the inspection and export slides: confirm units and overall scale, check that walls are thick enough for the intended printer, identify unsupported overhangs, select a sensible orientation, use the software’s repair or validation tools, and export an STL where appropriate. Students annotate the corresponding sections of the CAD production-readiness checklist and ask clarifying questions. Emphasise that the exact minimum wall thickness and overhang limit depend on the school’s printer, material and slicer settings.

3. 15–20 min · Safety and production briefing. Teacher explains that today’s work is digital preparation only: students must save regularly, use their own folder, avoid overwriting the original file, and ask before changing shared printer or slicer settings. Students open their latest CAD file, create a clearly named working copy, and complete the first identification fields on the worksheet.

4. 20–42 min · CAD inspection and refinement. Teacher circulates, questioning decisions and conferencing with students who identify errors; use the inspection workflow slides as a visual reference. Students inspect their model systematically, recording evidence on the worksheet, then correct errors such as open surfaces, unwanted gaps, unrealistic scale, fragile walls or unsupported features. They test the model using available CAD analysis tools and record at least one change and its reason.

5. 42–52 min · Orientation and export. Teacher models comparing two possible orientations and highlights trade-offs involving support material, surface quality, stability, strength, print time and waste using the orientation and export slides. Students choose and justify an orientation, check the model against the design criteria, export an STL or other teacher-approved production format, and save it using the agreed naming convention. They record the file name, format, scale and key settings on the worksheet.

6. 52–58 min · Peer quality check. Teacher pairs students for a structured review and displays the peer-check prompts in the peer review slides. Students exchange screens or files and check one another’s model for scale, thickness, overhangs, orientation, file naming and visible errors. Each student gives one specific improvement suggestion; the owner accepts, rejects or investigates it and explains why.

7. 58–60 min · Exit reflection and pack-up. Teacher asks students to complete the final reflection on the CAD production-readiness checklist before closing devices. Students state whether their model is production-ready, identify the remaining risk, and submit or place the exported file in the nominated class folder.

Resources

• CAD software and student project files
• Computers or laptops for 25 students
• Access to the school’s 3D printer specifications or slicer guidelines
• the Preparing a Model for Production slide deck
• the CAD production-readiness checklist
• Teacher demonstration model showing a successful and failed print
• Class folder with agreed file-naming convention
• Projector or interactive display
• Headphones where required

Assessment

• Circulate during inspection and use questioning to check whether students can link a model feature to a production consequence, such as weak walls or excessive support material.
• Check each worksheet for recorded evidence, a justified orientation, a documented correction and accurate export details.
• Collect the final reflection and exported file. Confirm that the file opens, is correctly named and uses an appropriate format. Record students requiring further support before production.

Differentiation

• Provide a visual, step-by-step checklist, teacher demonstration file and a short list of common CAD errors for students requiring support. Pair students strategically for the peer check.
• Offer sentence starters such as “I selected this orientation because…” and “This feature may fail because…”. Allow students to explain decisions orally where extended writing is a barrier.
• Provide enlarged screenshots, repeated demonstrations and teacher or peer conferencing for students with visual, processing or fine-motor needs. Ensure software accessibility settings are enabled.
• Extend capable students by asking them to compare two orientations or export settings and justify the best balance of strength, surface quality, sustainability and print time.
• Reinforce the school values: respect others’ designs during peer review, show integrity by reporting errors honestly, and pursue excellence through careful testing and refinement.