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.
Author(s): Hendrickson A.
Year: 2008
Language: English
Pages: 430
Front Cover......Page 1
Mechanical Design for the Stage......Page 4
Copyright Page......Page 5
Table of Contents......Page 6
Preface......Page 14
Part I: The Physics of Stage Machinery......Page 18
Fundamentals......Page 20
Displacement......Page 21
Definition of Translational Displacement......Page 22
Speed and Velocity......Page 24
Graphical Relationships Between x, v, and a......Page 26
Problems......Page 29
Constant Acceleration......Page 30
Equations of Constant Acceleration......Page 31
Moves with a Given Time and Distance......Page 35
The Acceleration Due to Gravity......Page 37
Problems......Page 39
Newton's Laws of Motion......Page 40
Mass and Force......Page 41
Conversion Table – Mass and Force......Page 42
Weight......Page 43
The Force Needed to Accelerate Mass......Page 44
Problems......Page 45
Friction—Complex and Simplified......Page 46
Definitions......Page 47
Sliding Friction......Page 49
Static Friction......Page 50
Kinetic Friction......Page 52
Measuring Coefficients of Friction......Page 53
Rolling Friction......Page 55
Friction of Ropes on Cylinders......Page 57
Problems......Page 60
The Lifting Force......Page 62
Counterweighting......Page 63
Problems......Page 65
Power......Page 66
Maximum Power......Page 68
Maximum Force......Page 72
Problems......Page 74
Coordinate Systems......Page 76
Angular Displacement......Page 77
Angular Speed......Page 79
Converting Between Linear and Rotational......Page 80
An Aside: Centripetal Acceleration......Page 81
The Equations of Constant Angular Acceleration......Page 82
Torque......Page 83
Problems......Page 85
Overview......Page 88
Moment of Inertia......Page 89
Transferring the Axis of Rotation......Page 92
An Aside: WK[sup(2)]......Page 94
The Torque to Accelerate Mass......Page 95
Rolling Objects......Page 101
Problems......Page 103
Rotation and Friction......Page 104
The Torque Due to Friction, T[sub(friction)]......Page 105
Caster Friction and Turntables......Page 106
Rotational Bearing Friction......Page 112
Problems......Page 117
Overview......Page 120
The Center of Mass......Page 121
The Lifting Torque......Page 123
Problems......Page 127
Power......Page 130
Maximum Power......Page 132
Maximum Torque......Page 141
An Important Caveat—Mass and Spring Vibrations......Page 143
Problems......Page 144
Combining Linear and Rotational Power......Page 146
Converting Terms within the Power Formula......Page 150
Combining Multiple Speed Effects......Page 153
Problems......Page 158
Part II: Stage Machinery Components......Page 160
General Concepts......Page 162
Hazard Abatement......Page 163
Single Failure Proof Design......Page 164
Design Factor and Factor of Safety......Page 165
Codes and Standards......Page 167
Formalized Procedures......Page 169
Inspection and Maintenance......Page 170
Additional Information Sources......Page 171
Electric Motors......Page 172
Common Motor Types......Page 173
Sizes and Configurations......Page 174
The Speed/Torque Curve......Page 176
Choosing an Electric Motor......Page 177
Pneumatic Actuators......Page 178
Cylinders......Page 179
Stop Tube......Page 182
Cylinder Selection......Page 183
Counterbalance Valves......Page 184
Additional Information Sources......Page 185
Speed Reduction......Page 186
Speed Reduction Methods......Page 188
Gear Reducers......Page 190
Terms Used in Gear Reducer Selection......Page 191
Using the Reducer Ratings......Page 195
Gear Motor Selection......Page 197
Roller Chain......Page 198
Roller Chain Strength......Page 199
Roller Chain Sprockets......Page 201
V-belts and Sheaves......Page 202
Additional Information......Page 203
Shaft Strength......Page 204
Shaft Diameter and Torsional Stiffness Rule of Thumb......Page 206
Other Shaft Stress Sources......Page 207
Combined Torque and Bending Shaft Analysis......Page 208
Stress Concentrations......Page 210
Keys and Keyways......Page 211
Practical Shaft Design Considerations......Page 212
Jaw Couplings......Page 213
Universal Joints......Page 214
Types of Bushings......Page 216
Additional Information......Page 217
Bearings......Page 218
Rolling Element Bearings......Page 219
Plain Bearings......Page 220
Calculating Pressure and Velocity......Page 221
Mounted Bearings......Page 222
Linear Bearings......Page 224
Slewing Rings, or Turntable Bearings......Page 225
Cam Followers......Page 226
Track Capacity......Page 227
Bearing Selection Considerations......Page 228
Wheel and Caster Terminology......Page 229
Specialty Wheels......Page 230
Additional Information......Page 231
Wire Rope Terminology......Page 232
Sheave Terminology......Page 236
Additional Information Sources......Page 239
Drum Types......Page 240
Drum Sections......Page 241
Groove Dimensions......Page 243
Drum Groove Threads per Inch Values......Page 244
Drum Construction......Page 246
Drum Reeving......Page 247
Additional Information Sources......Page 248
Screw Mechanism Basics......Page 250
Sliding Contact Screws: Acme Screws......Page 251
Rolling Contact Screws: Ball Screws......Page 252
Common Screw Mechanism Uses......Page 253
Spring-Set Brakes......Page 256
Brake Noise......Page 257
Brake Placement......Page 259
Manual Release......Page 260
Fluid Power Brake Circuits......Page 261
Brake Engage and Release Speed......Page 262
Additional Information......Page 263
External Sensors......Page 264
Position Sensing......Page 265
Limit Box Ratios......Page 267
Disconnects......Page 268
Connectors......Page 269
Additional Information Sources......Page 270
Open vs. Enclosed Frames......Page 272
Stock Shapes vs. CNC Plates......Page 273
Mounting and Handling Options......Page 275
Structural Design Considerations......Page 276
Part III: A Mechanical Design Process......Page 280
Overview......Page 282
Five Key Points......Page 283
Mechanical Design in Industry and Theatre......Page 286
Influences on an Individual's Design Abilities......Page 289
A Brief Overview of the Mechanical Design Process......Page 291
Overview......Page 296
When a Written Specification Is Useful......Page 298
Elements of a Complete Specification......Page 299
Summary......Page 313
Overview......Page 314
Concept Generation Techniques......Page 315
Concept Evaluation......Page 321
An Evaluation Matrix......Page 322
Degrees of Freedom......Page 323
Some Diverse Constraint Issues......Page 326
Analysis......Page 328
Failure Modes and Effects Analysis, FMEA......Page 330
Drafting......Page 332
Overview......Page 334
Design for Fabrication Issues......Page 335
Outside Part Fabrication......Page 339
Design for Assembly......Page 342
Conclusion......Page 347
Part IV: A Compendium of Stage Machinery......Page 348
Overview......Page 350
Machine Details Common to Many Machines......Page 351
Backup Needs and Techniques......Page 353
Typical Applications......Page 358
Chain Drive Winch Concepts......Page 361
Direct Drive Winch Concepts......Page 363
Zero Fleet Angle Winch Concepts......Page 367
Winch Specification Issues......Page 372
Overview......Page 376
A Typical Application......Page 377
Turntable Drive Concepts......Page 384
Limited Rotation Turntable Drive Concepts......Page 393
Machine Details......Page 396
Turntable Drive Specification......Page 398
Overview......Page 402
A Typical Application......Page 403
Lift Concepts......Page 410
Hydraulic Cylinder Run Lifts and Leveling Techniques......Page 418
Lift Specification......Page 421
Overview......Page 424
Typical Applications......Page 425
Deck Track Drive Concepts......Page 434
Electric Dogs......Page 437
Bibliography......Page 440
C......Page 444
I......Page 445
S......Page 446
X......Page 447
