Design Scope¶

Rationale: 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.

Checklist¶

1. Behavior sketches. These may take different forms, but a useful model is a set of storyboards illustrating all the possible behaviors of the piece.

2. Detailed sketches. These are not yet production drawings; the purpose of these sketches is to resolve mechanical design approaches, select materials, establish part scale, and identify all interferences and interactions between parts.

   As partial example, for a notional arm modeling a human skeleton, this might include:

   1. top and side views of the hand showing individual phalanges and tendon paths.
   2. top and side detail sketches, showing finger joint construction, with shafts and bearing surfaces indicated.
   3. top and side views of the wrist, showing finger base joint placement, forearm connection, and load cell placement.
   4. top and side views of the forearm, showing the structural elements, cross braces, elbow bearing structure, finger actuator placement, and tendon paths.
   5. top and side views detailing the elbow joint, showing the structural elements, bearing locations, shafting, shaft retention, limit stop surfaces, range of travel, and actuator link placement.
   6. ...

   The full list would include similar drawings for the humeral section (upper arm), shoulder joint, scapular section(shoulder), and the mounting to the base.

3. Electronics sketch. Our electronic systems do not typically require highly engineered solutions, but often require purchasing particular components. If your project requires more specialized development, please provide a block diagram of the electronics system, identify particular resources needed, and outline the early tests and critical milestones.

4. Software sketch. Our software development does not typically require acquiring outside resources and so does not have much impact on the fabrication decisions. However, if your project requires significant development, please provide a block diagram of the software system, identify particular libraries or tools required, and outline the early tests and critical milestones.

5. Revised schedule. (See Project Work Plan for discussion of milestones).

6. Full bill of materials (accounting for every individual part).

7. Revised budget.