DIY Walkers
  • Home
  • Walker ABC's
  • Build Instructions
    • TrotBot Builds >
      • TrotBot Linkage Plans
      • TrotBot's Legs Simplified
      • Quadruped TrotBot
      • Hexapod TrotBot
      • TrotBot
      • TrotBot, Ver 3
      • Mindstorms TrotBot, Ver 3
      • Wooden TrotBots by Automata Korea Design
      • 3D Printed TrotBot by Scott Anderson
      • Mindstorms TrotBot, Ver 2
      • Mindstorms TrotBot
      • Large-Scale TrotBot
    • Strider Builds >
      • Strider Linkage Plans
      • Strider Ver 3's Legs
      • Strider Ver 3's Frame
      • Mindstorms Strider Ver 3 Mod
      • Strider
      • Strider's Legs Simplified (ver 2's)
      • RC Strider
    • Mechanical Spider >
      • Klann Mechanical Spider - Climbing Mod
      • Klann's Spider, EV3 Long Legs
      • Klann High-Step Mod
      • Klann's Spider, Ver 2
      • Mindstorms Klann
      • Klann's Spider, Ver 1
      • Klann's Linkage Plans
    • Strandbeest
    • LEGO Spot Micro
    • Linkage Warm Ups >
      • Lever Paradox
      • LEGO Biters
      • LEGO Punchers (4 bar linkage warm-up)
      • LEGO Hopping Robot
    • Hiro Labo
    • Whegs (wheel-legs)
  • Customize
    • Strider Linkage Optimizer
    • Klann Linkage Optimizer
    • Strandbeest Optimizer for LEGO
    • TrotBot Optimizer
    • 4 Bar Linkage Optimizer
    • 4 Bar Walking Linkage
    • 6 Bar Walking Linkage
  • Linkage Simulation
    • Python Linkage Simulator
    • Scratch Linkage Simulator
  • Blog

Transfering Torque with LEGO Axles

12/5/2016

6 Comments

 
Walkers with multiple pairs of legs spaced out from the frame subject axles to more stress than what they are typically designed to handle.   Furthermore, LEGO's plastic axles twist easily under torque, which can be especially problematic for walkers since such twisting can disrupt a walker's gait by delaying the leg's movement.  

How much do LEGO axles twist?
​
The above experiment was run with LEGO's M-motor 8883, geared down in a 5:1 ratio - the same set up I used for TrotBot.
Picture
Plastic LEGO axle permanently twisted by a LEGO XL motor geared down by a 5:1 ratio

With some walkers the gait is smooth enough and the weight low enough that axle twisting doesn't harm the gait much.  However, with heavy and wide walkers, like the Mindstorms TrotBot I just finished, axle twisting can be a problem.   Fortunately, Brick Machine Shop makes stainless steel axles for LEGO:  
Picture

These steel axles resist twisting and help to keep leg movement closer to the mechanism's designed movement.  They also fit more tightly, so cranks won't come off axles while operating your walker - but this also means it is difficult to insert these axles into parts, so we pre-stretch the LEGO holes before putting the parts onto the robot (see below).   We also use a Kapla block, coin or needle nose pliers to make it easier to remove parts from the axles.  

Pre-Stretching LEGO axle holes:
Picture
Picture
Picture
Then, slide the part up and down the axle a couple times to widen the hole a bit more, using something like a Kapla block, coin, or needle nose pliers to increase your leverage.

We purchased these steel axles from former Bricklink store Brick Machine Shop.  UPDATE:  Brick Machine Shop is no longer on Bricklink, but you can find them on Ebay under the store name "CNCgear"
6 Comments
Debby Bass
11/7/2018 09:31:48 am

Where can you purchase these

Reply
Wade
11/7/2018 12:32:19 pm

Hi Debby,
we purchased the steel axles from Bricklink store Brick Machine Shop.

https://www.bricklink.com/store/home.page?p=Eezo#/shop?o={%22showHomeItems%22:1}

Their tight fit can be frustrating, but they work well. Good luck!

Reply
Eezo
3/15/2020 10:10:48 pm

They are made tight on purpose. Originally I made them looser and they wear out the plastic right away and gears slip. Making them tight give the assembly longevity. Brick Machine Shop is closed due to Lego buy Bricklink and killing custom products. I sell them on ebay now.

Emery D link
1/9/2021 12:33:52 am

Thanks for writingg this

Reply
Wade
1/12/2021 08:04:58 am

You're welcome!

Reply
Sump Pump Installation Allapattah link
9/4/2022 07:07:27 am

This is a greaat post thanks

Reply



Leave a Reply.

    Categories

    All
    Challenge Questions
    Experiments
    Feet
    Klann
    Strandbeest
    Strider
    Structure
    TrotBot

    Archives

    February 2023
    June 2021
    October 2018
    August 2018
    July 2018
    May 2018
    January 2018
    December 2017
    November 2017
    September 2017
    August 2017
    July 2017
    June 2017
    May 2017
    April 2017
    March 2017
    February 2017
    January 2017
    December 2016
    October 2016

    RSS Feed

  • Home
  • Walker ABC's
  • Build Instructions
    • TrotBot Builds >
      • TrotBot Linkage Plans
      • TrotBot's Legs Simplified
      • Quadruped TrotBot
      • Hexapod TrotBot
      • TrotBot
      • TrotBot, Ver 3
      • Mindstorms TrotBot, Ver 3
      • Wooden TrotBots by Automata Korea Design
      • 3D Printed TrotBot by Scott Anderson
      • Mindstorms TrotBot, Ver 2
      • Mindstorms TrotBot
      • Large-Scale TrotBot
    • Strider Builds >
      • Strider Linkage Plans
      • Strider Ver 3's Legs
      • Strider Ver 3's Frame
      • Mindstorms Strider Ver 3 Mod
      • Strider
      • Strider's Legs Simplified (ver 2's)
      • RC Strider
    • Mechanical Spider >
      • Klann Mechanical Spider - Climbing Mod
      • Klann's Spider, EV3 Long Legs
      • Klann High-Step Mod
      • Klann's Spider, Ver 2
      • Mindstorms Klann
      • Klann's Spider, Ver 1
      • Klann's Linkage Plans
    • Strandbeest
    • LEGO Spot Micro
    • Linkage Warm Ups >
      • Lever Paradox
      • LEGO Biters
      • LEGO Punchers (4 bar linkage warm-up)
      • LEGO Hopping Robot
    • Hiro Labo
    • Whegs (wheel-legs)
  • Customize
    • Strider Linkage Optimizer
    • Klann Linkage Optimizer
    • Strandbeest Optimizer for LEGO
    • TrotBot Optimizer
    • 4 Bar Linkage Optimizer
    • 4 Bar Walking Linkage
    • 6 Bar Walking Linkage
  • Linkage Simulation
    • Python Linkage Simulator
    • Scratch Linkage Simulator
  • Blog