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Mechanical Design for the Stage

Book Description

Scenic effects involving rotating turntables, tracking stage wagons, and the vertical movement of curtains and painted drops have become common in both Broadway and Regional theatre productions. The machines that drive these effects range from small pneumatic cylinders pushing loads of a few pounds an inch or two, to 40 horsepower winches running multi-ton scenery at speeds 6 feet per second or more. Usually this machinery is designed by theatre technicians specifically for a particular show's effect. Compared to general industry, this design process is short, often only a few days long, it is done by one person, design teams are rare, and it is done in the absence of reference material specifically addressing the issues involved. The main goal of this book is to remedy this last situation.

Mechanical Design for the Stage will be a reference for you that will:
* provide the basic engineering formulas needed to predict the forces, torques, speeds, and power required by a given move
* give a technician a design process to follow which will direct their work from general concepts to specific detail as a design evolves, and
* show many examples of traditional stage machinery designs.

The book's emphasis will be on following standard engineering design and construction practices, and developing machines that are functional, efficient to build, easily maintained, and safe to use.

Table of Contents

  1. Cover
  2. Halftitle
  3. Title
  4. Copyright
  5. Table of Contents
  6. Preface
  7. Part I: The Physics of Stage Machinery
    1. 1 Basic Concepts & Definitions
      1. Fundamentals
      2. Displacement
      3. Definition of Translational Displacement
      4. Speed and Velocity
      5. Acceleration
      6. Graphical Relationships Between x, v, and a
      7. Problems
    2. 2 The Equations of Constant Acceleration
      1. Constant Acceleration
      2. Equations of Constant Acceleration
      3. Moves with a Given Time and Distance
      4. The Acceleration Due to Gravity
      5. Problems
    3. 3 The Force to Accelerate Mass: F acceleration
      1. Overview
      2. Newton’s Laws of Motion
      3. Mass and Force
      4. Conversion Table – Mass and Force
      5. Weight
      6. The Force Needed to Accelerate Mass
      7. Problems
    4. 4 The Friction Force, F friction
      1. Friction—Complex and Simplified
      2. Definitions
      3. Sliding Friction
      4. Static Friction
      5. Kinetic Friction
      6. Measuring Coefficients of Friction
      7. Rolling Friction
      8. Friction of Ropes on Cylinders
      9. Problems
    5. 5 The Lifting Force, F lifting
      1. Gravity, Weight, and the Lifting Force
      2. The Lifting Force
      3. Counterweighting
      4. Problems
    6. 6 Maximum Power and Force
      1. Power
      2. Maximum Power
      3. Maximum Force
      4. Problems
    7. 7 Basic Concepts of Rotational Motion
      1. Definition of Rotational Motion
      2. Coordinate Systems
      3. Angular Displacement
      4. Angular Speed
      5. Angular Acceleration
      6. Converting Between Linear and Rotational
      7. An Aside: Centripetal Acceleration
      8. The Equations of Constant Angular Acceleration
      9. Torque
      10. Problems
    8. 8 The Torque to Accelerate Mass, T accel
      1. Overview
      2. Moment of Inertia
      3. Transferring the Axis of Rotation
      4. An Aside: WK 2
      5. The Torque to Accelerate Mass
      6. Rolling Objects
      7. Problems
    9. 9 The Torque to Overcome Friction, T friction
      1. Rotation and Friction
      2. The Torque Due to Friction, T friction
      3. Caster Friction and Turntables
      4. Rotational Bearing Friction
      5. Problems
    10. 10 The Lifting Torque, T lift
      1. Overview
      2. The Center of Mass
      3. The Lifting Torque
      4. Problems
    11. 11 Maximum Power and Torque
      1. Power
      2. Maximum Power
      3. Maximum Torque
      4. An Important Caveat—Mass and Spring Vibrations
      5. Problems
    12. 12 Combining Multiple Motions
      1. Overview
      2. Combining Linear and Rotational Power
      3. Converting Terms within the Power Formula
      4. Combining Multiple Speed Effects
      5. Problems
  8. Part II: Stage Machinery Components
    1. 13 Safety
      1. General Concepts
      2. Risk Assessment
      3. Hazard Abatement
      4. Single Failure Proof Design
      5. Design Factor and Factor of Safety
      6. Emergency Stop
      7. Codes and Standards
      8. Formalized Procedures
      9. Inspection and Maintenance
      10. Additional Information Sources
    2. 14 Actuators
      1. Electric, Hydraulic or Pneumatic
      2. Powering the Actuator
      3. Electric Motors
      4. Common Motor Types
      5. Sizes and Configurations
      6. The Speed/Torque Curve
      7. Enclosures
      8. Service Factor
      9. Choosing an Electric Motor
      10. Hydraulic Actuators
      11. Pneumatic Actuators
      12. Cylinders
      13. Stop Tube
      14. Cylinder Selection
      15. Counterbalance Valves
      16. Additional Information Sources
    3. 15 Speed Reduction
      1. Speed Reduction
      2. Speed Reduction Methods
      3. Gear Reducers
      4. Terms Used in Gear Reducer Selection
      5. Using the Reducer Ratings
      6. Gear Motor Selection
      7. Roller Chain
      8. Roller Chain Strength
      9. Roller Chain Sprockets
      10. Roller Chain Guidelines
      11. V-belts and Sheaves
      12. Toothed Belts
      13. Additional Information
    4. 16 Shafting
      1. Shaft Basics
      2. Shaft Strength
      3. Shaft Diameter and Torsional Stiffness Rule of Thumb
      4. Other Shaft Stress Sources
      5. Combined Torque and Bending Shaft Analysis
      6. Resonant Speed
      7. Stress Concentrations
      8. Keys and Keyways
      9. Practical Shaft Design Considerations
      10. Jaw Couplings
      11. Roller Chain Couplings
      12. Universal Joints
      13. Types of Bushings
      14. Additional Information
    5. 17 Bearings and Wheels
      1. Bearings
      2. Rolling Element Bearings
      3. Plain Bearings
      4. Calculating Pressure and Velocity
      5. Mounted Bearings
      6. Linear Bearings
      7. Slewing Rings, or Turntable Bearings
      8. Cam Followers
      9. Track Capacity
      10. Bearing Selection Considerations
      11. Wheels and Casters
      12. Wheel and Caster Terminology
      13. Specialty Wheels
      14. Additional Information
    6. 18 Wire Rope and Sheaves
      1. Wire Rope
      2. Wire Rope Terminology
      3. Inspection
      4. Sheave Terminology
      5. Additional Information Sources
    7. 19 Cable Drums
      1. Grooved Cable Drums
      2. Drum Types
      3. Drum Sections
      4. Drum Materials
      5. Groove Dimensions
      6. Drum Diameter
      7. Drum Width
      8. Drum Groove Threads per Inch Values
      9. Cable Anchors
      10. Drum Construction
      11. Drum Reeving
      12. Additional Information Sources
    8. 20 Screw Mechanisms
      1. Screw Mechanism Basics
      2. Sliding Contact Screws: Acme Screws
      3. Rolling Contact Screws: Ball Screws
      4. Common Screw Mechanism Uses
    9. 21 Brakes
      1. Spring-Set Brakes
      2. Brake Noise
      3. Brake Placement
      4. Manual Release
      5. Orientation
      6. Fluid Power Brake Circuits
      7. Overspeed Braking
      8. Brake Engage and Release Speed
      9. Additional Information
    10. 22 Control Components
      1. External Sensors
      2. Position Sensing
      3. Limit Box Ratios
      4. Disconnects
      5. Connectors
      6. Additional Information Sources
    11. 23 Frames and Framing
      1. General Concepts
      2. Open vs. Enclosed Frames
      3. Stock Shapes vs. CNC Plates
      4. Steel vs. Aluminum
      5. Mounting and Handling Options
      6. Structural Design Considerations
  9. Part III: A Mechanical Design Process
    1. 24 Mechanical Design in Theatre
      1. Overview
      2. Five Key Points
      3. Mechanical Design in Industry and Theatre
      4. Influences on an Individual’s Design Abilities
      5. A Brief Overview of the Mechanical Design Process
    2. 25 Developing a Design Specification
      1. Overview
      2. When a Written Specification Is Useful
      3. Elements of a Complete Specification
      4. Summary
    3. 26 Concept Design
      1. Overview
      2. Concept Generation Techniques
      3. Concept Evaluation
      4. An Evaluation Matrix
      5. Freedom and Constraint
      6. Degrees of Freedom
      7. Some Diverse Constraint Issues
    4. 27 Detail Design
      1. Overview
      2. Analysis
      3. Failure Modes and Effects Analysis, FMEA
      4. Parts and Materials List
      5. Drafting
    5. 28 Design for Manufacture
      1. Overview
      2. Design for Fabrication
      3. Design for Fabrication Issues
      4. Outside Part Fabrication
      5. Design for Assembly
      6. Conclusion
  10. Part IV: A Compendium of Stage Machinery
    1. 29 A Compendium of Stage Machinery
      1. Overview
      2. Machine Details Common to Many Machines
      3. Backup Needs and Techniques
    2. 30 Winches
      1. Overview
      2. Typical Applications
      3. Cable Drum Winch Concepts
      4. Chain Drive Winch Concepts
      5. Direct Drive Winch Concepts
      6. Zero Fleet Angle Winch Concepts
      7. Machine Details
      8. Winch Specification Issues
    3. 31 Turntable Drives
      1. Overview
      2. A Typical Application
      3. Turntable Drive Concepts
      4. Limited Rotation Turntable Drive Concepts
      5. Machine Details
      6. Turntable Drive Specification
    4. 32 Lifts
      1. Overview
      2. A Typical Application
      3. Lift Concepts
      4. Hydraulic Cylinder Run Lifts and Leveling Techniques
      5. Lift Specification
    5. 33 Tracked Scenery
      1. Overview
      2. Typical Applications
      3. Deck Track Drive Concepts
      4. Electric Dogs
  11. Bibliography
  12. Index