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Lesson 89

Independent Project Drawing Package

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Hello! Welcome back.

In our last session, we focused on making your design robust and producible by applying DFMA principles and conducting a risk assessment with FMEA. You identified potential failure modes and thought about how manufacturing constraints should influence your geometry. Today, we translate those critical design decisions into a formal, professional format.

This lesson addresses the learning outcome: Create a complete drawing package for the independent project, including assembly, sub-assembly, and detailed part drawings. An engineering drawing is more than just a picture; it's a legal contract that tells a manufacturer exactly what to build. It is the primary document where you communicate the critical features you identified through your tolerance analyses, DFMA, and FMEA work.

1. The Anatomy of a Professional Drawing Package

For any non-trivial product, a single drawing is not enough. A professional "drawing package" or "drawing set" is a collection of documents that fully defines the entire product. It typically follows a hierarchical structure:

  • Top-Level Assembly Drawing: This is the master drawing. It shows how all the major components and sub-assemblies fit together. Its main purpose is to define the overall product structure. Key elements usually include:

    • An exploded isometric view to show the assembly sequence.
    • A Bill of Materials (BOM) table listing every part.
    • Balloon callouts linking the parts in the view to the BOM.
    • Overall envelope dimensions.

  • Sub-Assembly Drawings: If your project contains complex, self-contained mechanisms (like a gearbox or a linear actuator assembly), they get their own assembly drawing. The format is the same as the top-level assembly drawing, just for a smaller portion of the product.

  • Detail (or Part) Drawings: This is the blueprint for manufacturing a single, non-standard component. It must contain all the information needed to fabricate the part from raw material without any further questions. This includes multiple views, all dimensions, tolerances, material specifications, and any required notes on finishes or treatments.

2. Getting Started with Onshape Drawings

Let's dive into the Onshape environment and learn the fundamental workflow for creating a drawing. While you have a strong background in engineering principles, the tooling in each CAD package is specific. This video provides an excellent, concise overview.

Onshape - Drawings Overview - How to Create New Drawings, Views, and Dimensions

This video, 'Onshape - Drawings Overview' from the Creo Parametric channel, will walk you through the entire process from starting a new drawing to placing views and adding dimensions.

Please watch the video from the beginning to 15:12. As you watch, pay close attention to the workflow: Creating Views (00:00 - 05:08): How to create a new drawing, select a template, and place base, projection, isometric, and section views. Adding Supplemental Geometry (05:08 - 07:10): The use of center marks and centerlines to add clarity. Dimensioning (07:10 - 13:11): How to apply various dimension types, including linear, radial, and chamfer dimensions, and how to modify their properties. Adding Notes (13:11 - 15:12): How to place general notes and link them to model properties for dynamic updates.

This video covers the essential mechanics. For a more structured, in-depth reference that you can refer back to, the Onshape Learning Center provides a self-paced course. I've linked it below. You don't need to read it now, but know that it's a valuable resource if you want to explore a specific topic in more detail.

Detailed Drawings - Onshape Learning Center

The Onshape Learning Center's 'Detailed Drawings' course provides comprehensive written tutorials on every aspect of creating drawings. Bookmark this for future reference.

You don't need to read this now. This is a reference for you to use during the practical exercise or later. It contains short lessons on everything from 'Inserting Views' and 'Assembly Views' to 'Dimensioning' and 'Inserting BOMs'.

3. Assembling the Package: Key Drawing Types

Now let's focus on the specific content for assembly and detail drawings, which form the core of your drawing package.

Creating the Assembly Drawing

The assembly drawing is your project's table of contents. It communicates what the product is and what parts it contains.

Onshape Exploded Assembly Drawing of a Brace
An excellent example of an assembly drawing in Onshape. Note the key elements: an exploded isometric view, a Bill of Materials (BOM) in the top-right, and callouts (balloons) identifying each part.

To create this in Onshape, the key steps are:

  1. Insert an Assembly View: When you insert a view, choose your top-level assembly.
  2. Use an Exploded View: In the view properties, you can select one of the exploded views you previously created in the Assembly environment. This is crucial for showing how parts fit together.
  3. Insert a BOM Table: Use the "BOM table" tool. Onshape automatically generates this based on the parts in your assembly.
  4. Add Callouts: Use the "Callout" tool to create the balloons that link the parts in the view to the item numbers in the BOM.

Creating the Detail Drawing

This is where your DFMA and FMEA insights become contractual obligations. The detail drawing is the single source of truth for manufacturing one specific part. A manufacturer should be able to build the part using only this drawing.

Onshape Crankshaft Technical Drawing
A detailed part drawing of a crankshaft. It contains multiple orthographic views to show the geometry from all sides, a section view to clarify internal features, an isometric view for context, and comprehensive dimensions and annotations.

A complete detail drawing includes:

  • Orthographic Views: A set of 2D views (e.g., front, top, right side) that fully describe the part's geometry. Use as many views as necessary to make every feature clear.
  • Section and Detail Views: Use section views to show internal features and detail views to show small, complex areas at a larger scale.
  • Complete Dimensioning: Every feature must be fully dimensioned. The goal is to leave no ambiguity for the machinist.
  • Tolerances: Critical dimensions identified in your stack-up analysis must have their tolerances specified.
  • Notes: Specify the material, any required heat treatments, surface finishes, deburring requirements, etc.
Test your understanding!

You are creating a detail drawing for a custom-machined aluminum mounting plate. You add front, top, and right-side views. However, the plate has a complex pocket with several small features on the inside. What two additional view types could you add to the drawing to make the geometry of this pocket perfectly clear to the manufacturer?

Show answer
  1. A Section View: By creating a cutting plane line that passes through the pocket, you can create a section view that reveals its internal profile and features without any hidden lines.
  2. A Detail View: If the pocket contains very small features (like a small chamfer or corner radius) that are hard to dimension in the main views, you can circle that area and create a magnified detail view to show and dimension it clearly.

4. Practical Application: Create Your Project's Drawing Package (25 minutes)

It's time to apply these concepts to your independent project. This exercise will form the foundation of your final project documentation.

  1. Create the Assembly Drawing:

    • In your Onshape project, create a new drawing using an appropriate ANSI or ISO template.
    • Insert a view of your top-level assembly. Set the view orientation to Isometric and choose your exploded view.
    • Insert a BOM table. For now, the default table is fine.
    • Use the Callout tool to add balloons to at least 4-5 key parts, linking them to the BOM.

  2. Create a Detail Drawing:

    • Add a new sheet to your drawing file using the "Sheets" panel on the left.
    • Choose one custom-made part from your assembly that would require manufacturing (e.g., a bracket, a plate, a custom shaft).
    • Insert at least three orthographic views (e.g., Front, Top, Right) and one Isometric view of this part.
    • Add centerlines and center marks to all relevant holes and cylindrical features.
    • Apply all necessary dimensions to fully define the part's geometry. Don't worry about GD&T symbols yet, just the basic dimensions.
    • Add a Note to specify the material for the part (e.g., "MATERIAL: 6061-T6 ALUMINUM").

This is a significant task, so take your time and refer back to the video or the Onshape Learning Center resource as needed. The goal is to create a solid first draft of your drawing package.

Conclusion

In this lesson, you have learned how to translate your 3D designs into a formal, 2D drawing package—the universal language of engineering and manufacturing. This is a critical step in turning a design concept into a physical reality and a cornerstone of a professional engineering portfolio.

Key Takeaways:

  • A complete drawing package consists of assembly, sub-assembly, and detailed part drawings.
  • Assembly drawings define the product structure and parts list using exploded views and a Bill of Materials (BOM).
  • Detail drawings are the manufacturing blueprints for individual parts, containing all necessary views, dimensions, tolerances, and notes.
  • Onshape provides a comprehensive set of tools for creating views, adding dimensions, annotating, and generating tables like a BOM.

Preview of the Next Lesson:
We've created the structure for our Bill of Materials in the assembly drawing. In the next lesson, we will finalize the Bill of Materials (BOM) with all components, quantities, and specifications. This involves moving beyond the default CAD data to add crucial real-world information like part numbers, suppliers, and material specifications, turning it into a true procurement document.