Project Work Plan

Revised for 2025; text not yet final.

Our next objective is to resolve all design details to the point where materials can be purchased and CAD drawings can begin.

Purchasing parts and materials frequently represents a key rate-limiting milestone on the critical path. Making efficient and successful purchasing decisions requires a clear plan for the overall bill of materials (BOM) and budget. However, producing this plan requires resolving the detailed design to a level where all elements have been identified. This typically requires drawing mechanical designs at a level sufficient to resolve all significant design decisions.

The next step in the fabrication process will be producing individual part production drawings with final dimensions and features.

Learning Objectives

The assignment will help you to:

  1. Resolve conceptual requirements into tangible physical design details.

  2. Draw a machine design at a functional level to reveal needed parts and relations without final detail.

  3. Write a bill of materials.

Milestones

Each project will have specific unknowns which need to be resolved in order for the design to work. Our projects usually proceed through several smaller proof-of-concept demonstrations which test specific elements early.

Please carefully consider which critical elements are necessary for success and plan to test them first. It is tempting to begin designing the parts which are most familiar or likely to work, but that will be wasted effort if a fundamental assumption doesn’t hold.

Design Process

Drawing and sketching is the fastest way to explore all design questions. The key is disciplined drawing which evaluates part function and interactions at a meaningful level of detail. It it generally not as efficient to rush to CAD drawings; time committed to the detail of a CAD model may be wasted if the overall spatial and functional organization isn’t settled.

Bill of Materials

A Bill of Materials or BOM in engineering is a complete accounting of every component of a manufactured product. It is a useful tool for managing the complete set of material requirements involved in fabricating a device.

A Bill of Materials is generally presented in tabular format; a Google Sheet is recommended. A rough template is available as BOM-template.xlsx.

For our purposes, a bill of materials typically involves three categories:

  1. Fabricated parts, e.g. parts you will laser-cut or 3D print. These may conceivably involve special materials not available from Lending, e.g. fabric.

  2. Special components not available in the standard lab stock. These may require purchasing or are sometimes available from the private class inventory.

  3. Stock lab parts, including both electronics and mechanical. A product manufacturing BOM will include every last fastener, but for our purposes this is not needed.

Deliverables

Please post a brief report to the appropriate shared folder. Please include the following:

  • a project or piece working title

  • concept statement (updated as needed)

  • prioritized plan of project milestones

  • detailed hand or drawings of the full prototype showing all external and internal parts to scale and relation (not yet CAD)

  • a bill of materials identifying all purchased and fabricated components