TECHNIC BUILDER’S GUIDE - No Starch Press · THIS BOOK IS NOT AUTHORIZED OR ENDORSED BY THE LEGO GROUP. ... The Unofficial LEGO Technic Builder’s Guide is filled with ... world-renowned

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THIS BOOK IS NOT AUTHORIZED OR ENDORSED BY THE LEGO GROUP.

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THE UNOFFICIAL LEGO® TECHNIC BUILDER’S GUIDEPaweł “Sariel” Kmiec

INSPIRATIONAL MODELS, COMPREHENSIVE BUILDING ADVICE, AND BUILDING INSTRUCTIONS FOR OVER 40 MECHANISMS

WHAT WILL YOU BUILD?™

The LEGO® Technic system opens a new realm of building possibilities. Using motors, gears, pneumatics, pulleys, linkages, and more, you can design LEGO models that really move.

The Unofficial LEGO Technic Builder’s Guide is filled with building tips for creating strong yet elegant machines and mechanisms with the Technic system. Author Paweł “Sariel” Kmiec will teach you the foundations of LEGO Technic build-ing, from simple machines to advanced mechanics, even explaining how to create realistic to-scale models. Sariel, a world-renowned LEGO Technic expert, offers unique insight into mechanical principles like torque, power translation, and gear ratios, all using Technic bricks. You’ll learn how to:

Create sturdy connections that can withstand serious stress

Re-create specialized LEGO pieces like casings and u-joints, and build solutions like Schmidt and Oldham couplings, when no standard piece will do

Build custom differentials, suspensions, transmissions, and steering systems

Pick the right motor for the job—and transform its proper-ties to suit your needs

Combine studfull and studless building styles for a stun-ning look

Create remote-controlled vehicles, lighting systems, motorized compressors, and pneumatic engines

This beautifully illustrated, full-color book will inspire you with ideas for building amazing machines like tanks with suspended treads, supercars, cranes, bulldozers, and much more. Your Technic adventure starts now!

about the author

Paweł “Sariel” Kmiec (http://sariel.pl/ ) is a prolific blogger and Technic model builder. He is YouTube’s most popular LEGO Technic builder, a guest blogger for the official LEGO Technic blog, and a 2012 LEGO Ambassador.

contents in detailforeword by Fernando Correia ................................................................................xv

preface ..................................................................................................................xvii

acknowledgments .................................................................................................xviii

part I basICs

1 basic concepts .......................................................................................................... 3speed...................................................................................................................................................................................... 3torque .................................................................................................................................................................................... 3power ..................................................................................................................................................................................... 3friction ................................................................................................................................................................................... 4traction .................................................................................................................................................................................. 4rolling resistance ................................................................................................................................................................ 4backlash ................................................................................................................................................................................ 5efficiency ............................................................................................................................................................................... 5vehicular concepts .............................................................................................................................................................. 5

driveshaft ..................................................................................................................................................................... 6drivetrain ..................................................................................................................................................................... 6driveline ........................................................................................................................................................................ 6steering lock ................................................................................................................................................................ 6turning radius ............................................................................................................................................................. 6FWD, RWD, 4×4, 4WD, and AWD .......................................................................................................................... 7weight distribution .................................................................................................................................................... 7center of gravity ......................................................................................................................................................... 7ground clearance ....................................................................................................................................................... 8

2 basic units and pieces .............................................................................................. 9the Technic brick ................................................................................................................................................................. 9pins, for joining and rotating .........................................................................................................................................10beams, the studless alternative ....................................................................................................................................12the half stud as the minimum building unit .............................................................................................................. 14two tricks for building with half studs ........................................................................................................................15

3 studless or studfull? .............................................................................................. 17LEGO evolving ................................................................................................................................................................... 17studfull building ................................................................................................................................................................18

reinforcing studfull constructions ....................................................................................................................... 19studfull advantages .................................................................................................................................................20studfull disadvantages ...........................................................................................................................................20

The Unofficial LEGO Technic Builder's Guide©2012, Paweł “Sariel” Kmieć

viii contents in detail

studless building ...............................................................................................................................................................20creating rigid studless connections ....................................................................................................................21studless advantages ................................................................................................................................................22studless disadvantages ..........................................................................................................................................23

combining the styles ........................................................................................................................................................23get inspired by Technic sets .................................................................................................................................. 24methods for connecting bricks and beams .......................................................................................................27even vs. odd ..............................................................................................................................................................28

4 axles, bushes, and joints ........................................................................................ 31axles .....................................................................................................................................................................................31

standard axles ..........................................................................................................................................................32modified axles ..........................................................................................................................................................33flexible axles..............................................................................................................................................................34

bushes .................................................................................................................................................................................35half bush ....................................................................................................................................................................35regular bush ..............................................................................................................................................................37bush with a long pin................................................................................................................................................37

universal joints ..................................................................................................................................................................38

part II meChanICs

5 gears and power transmission basics ..................................................................... 43drivers, followers, and idlers .........................................................................................................................................44gear ratios ..........................................................................................................................................................................45efficiency and gears .........................................................................................................................................................46backlash and gears ......................................................................................................................................................... 47controlling rotational direction ..................................................................................................................................... 47an inventory of gears ......................................................................................................................................................48

worm gear .................................................................................................................................................................488-tooth gear ............................................................................................................................................................. 49single-bevel 12-tooth gear ...................................................................................................................................50double-bevel 12-tooth gear .................................................................................................................................5014-tooth gear ...........................................................................................................................................................5016-tooth gear ...........................................................................................................................................................5016-tooth gear with clutch .....................................................................................................................................50single-bevel 20-tooth gear ...................................................................................................................................51single-bevel 20-tooth gear with pin hole .........................................................................................................51double-bevel 20-tooth gear .................................................................................................................................5124-tooth gear ...........................................................................................................................................................5224-tooth gear with clutch .....................................................................................................................................5224-tooth gear with crown .....................................................................................................................................5336-tooth gear ...........................................................................................................................................................5340-tooth gear ...........................................................................................................................................................53differential gears .....................................................................................................................................................53


contents in detail ix

turntables ..................................................................................................................................................................54knob wheel ................................................................................................................................................................55Hailfire Droid wheel gear ......................................................................................................................................55obsolete gears ..........................................................................................................................................................56

6 chains and pulleys .................................................................................................. 57chains ...................................................................................................................................................................................57pulleys.................................................................................................................................................................................. 59string and pulley systems ..............................................................................................................................................61

simple pulley system...............................................................................................................................................62differential pulley system ......................................................................................................................................63power pulley system ...............................................................................................................................................65

7 levers and linkages ................................................................................................ 67levers ................................................................................................................................................................................... 67

classes of levers .......................................................................................................................................................68from levers to linkages........................................................................................................................................... 69

linkages ...............................................................................................................................................................................71Chebyshev linkage ...................................................................................................................................................73Hoeken’s linkage ......................................................................................................................................................73pantograph ................................................................................................................................................................73Peaucellier–Lipkin cell............................................................................................................................................. 74Sarrus linkage .......................................................................................................................................................... 74Scott-Russell linkage ..............................................................................................................................................75scissor linkage ..........................................................................................................................................................75Watt’s linkage ........................................................................................................................................................... 76

8 custom mechanical solutions ................................................................................. 77a stronger differential .....................................................................................................................................................77differential locks ...............................................................................................................................................................78a custom differential ..................................................................................................................... 79an axle with a differential lock ..................................................................................................... 81ratchets ...............................................................................................................................................................................82linear clutches ...................................................................................................................................................................83eccentric mechanisms .....................................................................................................................................................84Scotch yokes ......................................................................................................................................................................85a scotch yoke ................................................................................................................................. 86Oldham couplings .............................................................................................................................................................87an oldham coupling ....................................................................................................................... 87Schmidt couplings ............................................................................................................................................................88stepper motors ..................................................................................................................................................................88Geneva mechanisms ........................................................................................................................................................89a geneva mechanism ..................................................................................................................... 90reverse lights .....................................................................................................................................................................90flashing lights ....................................................................................................................................................................91


x contents in detail

turn signals ........................................................................................................................................................................92complex turn signals...................................................................................................................... 94double-axle turntable transmission ...........................................................................................................................96a double-axle turntable transmission .......................................................................................... 97a sturdy universal joint ................................................................................................................................................ 101a universal joint ...........................................................................................................................101

9 the LeGO pneumatic system ................................................................................. 103the Old system ............................................................................................................................................................... 103the New system ............................................................................................................................................................. 104an inventory of pneumatic parts ............................................................................................................................... 105

pneumatic pump (Old) ......................................................................................................................................... 105pneumatic pump (New) ....................................................................................................................................... 105small pneumatic pump (New) ............................................................................................................................ 106distribution block (Old) ........................................................................................................................................ 106valve with studs .................................................................................................................................................... 106valve with no studs (New) ...................................................................................................................................107large cylinder (Old) ...............................................................................................................................................1076L cylinder (Old) ....................................................................................................................................................107small cylinder (New) ........................................................................................................................................... 108large cylinder with square base (New) .......................................................................................................... 108large cylinder with round base (New) ............................................................................................................ 108pneumatic tubes and hoses ............................................................................................................................... 108T-piece (Old) ........................................................................................................................................................... 109T-piece (New) ......................................................................................................................................................... 110hose connector with an axle joint (New) ........................................................................................................ 110cylinder bracket ..................................................................................................................................................... 110airtank ..................................................................................................................................................................... 111manometer ............................................................................................................................................................. 112

modding the pneumatic system ................................................................................................................................ 112non-LEGO hoses ................................................................................................................................................... 112non-LEGO airtanks .............................................................................................................................................. 112removing springs to create motorized compressors .................................................................................. 113pneumatic suspensions ....................................................................................................................................... 113turning your pneumatic system into a hydraulic one ................................................................................. 113

10 pneumatic devices ................................................................................................ 115motorized compressors ............................................................................................................................................... 115a rocking compressor ..................................................................................................................118motorized valves .............................................................................................................................................................119autovalve.......................................................................................................................................................................... 120a motorized valve ........................................................................................................................121an autovalve .................................................................................................................................122automated pressure switch ........................................................................................................................................ 123pneumatic engines .........................................................................................................................................................124a single-cylinder engine ..............................................................................................................125


contents in detail xi

a two-cylinder pneumatic engine ...............................................................................................128a two-cylinder pneumatic engine with sliders ...........................................................................131builder showcase ........................................................................................................................................................... 135a working water pressure pump ............................................................................................................................... 135

11 building strong ..................................................................................................... 137why things fall apart ..................................................................................................................................................... 137

finding weak links ................................................................................................................................................. 138understanding where to reinforce ................................................................................................................... 138

the right way to reinforce ............................................................................................................................................ 140things to remember when reinforcing .............................................................................................................142

reinforced differential casings.................................................................................................................................... 144four reinforced differential casings ...........................................................................................145reinforced worm gear casings ....................................................................................................................................149three reinforced worm gear casings ...........................................................................................150load-bearing structures ................................................................................................................................................151

rails, chassis, and body frames ..........................................................................................................................151trusses ..................................................................................................................................................................... 154choosing the right truss ...................................................................................................................................... 156

choosing the strongest pieces .....................................................................................................................................159

part III mOtOrs

12 an inventory of LeGO motors ............................................................................... 1632838, the first 9V motor ............................................................................................................................................. 16471427, a popular and powerful 9V motor ...............................................................................................................16543362, a lighter 9V motor ...........................................................................................................................................16547154, a 9V motor in a semitransparent housing ............................................................................................... 166Micromotor ...................................................................................................................................................................... 166NXT motor ........................................................................................................................................................................167Power Functions E motor .............................................................................................................................................167Power Functions Medium (M) motor ........................................................................................................................ 168Power Functions L motor ............................................................................................................................................ 168Power Functions XL motor ..........................................................................................................................................169Power Functions Servo motor ....................................................................................................................................169RC motor ...........................................................................................................................................................................170

13 LeGO power Functions system ............................................................................. 171manually controlling motors ......................................................................................................................................171remotely controlling motors ........................................................................................................................................172power supplies ................................................................................................................................................................174

AA battery box .......................................................................................................................................................174AAA battery box .....................................................................................................................................................174rechargeable battery ............................................................................................................................................175


xii contents in detail

receiver..............................................................................................................................................................................175remotes .............................................................................................................................................................................176

basic remote ...........................................................................................................................................................177speed control remote ...........................................................................................................................................177

modifying the remotes ..................................................................................................................................................177a basic remote with steering wheel ............................................................................................ 178a basic remote with sideways lever ............................................................................................ 179a speed control remote with central steering wheel .................................................................181linear actuators .............................................................................................................................................................. 183

large linear actuator ............................................................................................................................................ 183small linear actuator ............................................................................................................................................ 185linear actuators vs. pneumatics ........................................................................................................................ 185

extension wires .............................................................................................................................................................. 186miscellaneous elements ............................................................................................................................................... 187

switch ....................................................................................................................................................................... 187LED lights ............................................................................................................................................................... 187

part IV adVanCed meChanICs

14 wheeled steering systems .................................................................................... 191basic LEGO steering systems ......................................................................................................................................191

return-to-center steering ...................................................................................................................................194Ackermann steering geometry ..........................................................................................................................195a simple steering arm with ackermann geometry .............................................................. 198convergence of axles ............................................................................................................................................199

15 wheeled suspension systems ................................................................................ 203driven axles ..................................................................................................................................................................... 203suspension systems: concept and categories ....................................................................................................... 204types of suspensions .................................................................................................................................................... 205

double-wishbone independent suspension .................................................................................................. 206Tatra-type suspension ........................................................................................................................................ 207pendular suspension ............................................................................................................................................ 208trailing arm suspension (floating axle suspension) ..................................................................................... 209

driven and suspended axles ....................................................................................................................................... 209pendular suspension with turntables .............................................................................................................. 210a stabilized pendular suspension .........................................................................................211portal axles (geared hubs) ................................................................................................................................. 213a stabilized pendular suspension with a portal axle ...........................................................214a Tatra-type suspension stabilized with four shock absorbers ......................................... 217an independent suspension ..................................................................................................220a floating axle with four links ..............................................................................................222

steered and suspended axles ..................................................................................................................................... 225a pendular steered axle ........................................................................................................ 225an independent steered axle ................................................................................................ 226


contents in detail xiii

driven, steered, and suspended axles ...................................................................................................................... 227an independent axle ............................................................................................................227a heavy-duty pendular portal axle ......................................................................................230a pendular axle with a worm gear .......................................................................................236

16 tracked vehicles and suspensions ......................................................................... 241rubber tracks ...................................................................................................................................................................241hard plastic tracks ..........................................................................................................................................................242tracked wheel systems ................................................................................................................................................. 244suspension systems ...................................................................................................................................................... 246

bogies ....................................................................................................................................................................... 246trailing arms suspension with shock absorbers ............................................................................................247trailing arm suspensions with torsion bars ................................................................................................... 248

experimenting with road wheels ................................................................................................................................249

17 transmissions ....................................................................................................... 251types of transmissions ..................................................................................................................................................251how LEGO transmission driving rings work ........................................................................................................... 252transmission designs .................................................................................................................................................... 254

2-speed synchronized transmission................................................................................................................ 2542-speed linear heavy-duty transmission ....................................................................................................... 2542-speed RC motor transmission ...................................................................................................................... 2552-speed orbital transmission ............................................................................................................................ 2552-speed ratchet transmission ........................................................................................................................... 2563-speed linear transmission .............................................................................................................................. 2564-speed double-lever transmission ................................................................................................................ 2574-speed synchronized transmission ............................................................................................................... 2575-speed linear transmission .............................................................................................................................. 25810-speed synchronized transmission ..............................................................................................................259continuously variable transmission ................................................................................................................. 260

distribution transmissions ........................................................................................................................................... 260a 2-speed synchronized transmission ........................................................................................ 261a 2-speed linear heavy-duty transmission ................................................................................. 262a 2-speed rc motor transmission ...............................................................................................264a 2-speed orbital transmission ................................................................................................... 266a 2-speed ratchet transmission .................................................................................................. 267a 3-speed linear transmission ....................................................................................................268a 4-speed synchronized transmission ........................................................................................ 270a 10-speed synchronized transmission ......................................................................................271a continuously variable transmission ......................................................................................... 276

18 adders and subtractors ........................................................................................ 277hard-coupling ................................................................................................................................................................. 277coupling motors with adders ...................................................................................................................................... 277

summing torque with an adder ........................................................................................................................ 277adding more than two motors .......................................................................................................................... 280


xiv contents in detail

subtractors ...................................................................................................................................................................... 280why use a subtractor? ......................................................................................................................................... 281longitudinal subtractor ........................................................................................................................................ 282a longitudinal subtractor .....................................................................................................283transverse subtractor ......................................................................................................................................... 288a transverse subtractor ....................................................................................................... 289a studless transverse subtractor ........................................................................................291

part V mOdeLs

19 form vs. function ................................................................................................. 295cars .................................................................................................................................................................................... 295trucks ................................................................................................................................................................................ 296motorcycles .................................................................................................................................................................... 299tracked vehicles .............................................................................................................................................................. 299aircraft .............................................................................................................................................................................. 302

planes ...................................................................................................................................................................... 302helicopters .............................................................................................................................................................. 302

20 scaling a model ................................................................................................... 307blueprints ......................................................................................................................................................................... 307points of reference ........................................................................................................................................................ 309scaling ............................................................................................................................................................................... 309

21 the modeling process ........................................................................................... 315size matters .................................................................................................................................................................... 315wheels............................................................................................................................................................................... 316other circular elements .................................................................................................................................................319colors .................................................................................................................................................................................319devil in the details ......................................................................................................................................................... 320

building at odd angles.......................................................................................................................................... 321building cleverly ................................................................................................................................................... 323

the next step: controlling your models .................................................................................................................... 323

afterword ............................................................................................................. 325

index .................................................................................................................... 326

updates and additional resources ........................................................................ 334


Documents

TECHNIC BUILDER’S GUIDE - No Starch Press · THIS BOOK IS NOT AUTHORIZED OR ENDORSED BY THE LEGO GROUP. ... The Unofficial LEGO Technic Builder’s Guide is filled with ... world-renowned