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Stronger Leg Attachments for TrotBot Ver 3

7/27/2017

4 Comments

 
TrotBot's lower leg pins tend to come out when the legs experience sideways forces, as can happen when turning TrotBot on terrain with a lot of friction (like on thick carpeting).
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If the legs aren't snapped back in place, then friction on the pin's lips will wear them down, and the pins will no longer join with a sharp "snap", causing them to pull out more easily.  Ideally, joints should be 3 beams wide and symmetrical like the red chain of beams below, which prevents pins from pulling out or bending sideways when bearing weight: 
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However, using LEGO's parts to sandwich TrotBot's leg joints inline like the red beams above would add a lot of width to the robot.  Instead, I sandwiched the leg joints by attaching an additional 3x5 L-shaped beam to the outside of the legs, which is a bit off center but still works well with LEGO's high strength-to-weight ratios.  I tested these new attachments by turning TrotBot on some thick carpeting, which would usually cause a few of the leg's pins to pull out.   Below the video are some pictures of how I added the parts, and I used these attachments in my TrotBot version 3 builds. 
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I've got a few other ideas to test over the next few weeks, and then I'll post some new TrotBot instructions with the improvements. UPDATE:  Here are the new instructions with a part list.
4 Comments
Harold Carey
8/22/2017 12:50:03 am

Your instructions include several parts that I cannot find. Is the crank a EV3 part? Lego part? The curved portion 3D-printed and glued to a 3x5-hole EV "L"? Or is the entire product produced by a 3D printer?

Also, the short gray pins - - Lego parts?

Reply
Ben Vagle
9/4/2017 01:49:45 pm

I posted a parts list here:

https://www.diywalkers.com/trotbot-ver-3.html

Reply
Ben Vagle
8/22/2017 02:48:36 pm

Hi Harold,

Sorry for the confusion. Bricklink's description of the cranks is "Technic, Liftarm 3 x 5 L-Shape with Quarter Ellipse Thin".

And for the frictionless pin: "Technic, Pin without Friction Ridges Lengthwise"

Here are links to the parts:
https://www.bricklink.com/v2/catalog/catalogitem.page?id=1146#T=C&C=11
https://www.bricklink.com/v2/catalog/catalogitem.page?id=661#T=C

Reply
Ben Vagle
8/22/2017 03:13:26 pm

Sorry, the short gray pins used for the crank can be found here:
Technic, Pin 1/2
https://www.bricklink.com/v2/catalog/catalogitem.page?P=4274&name=Technic,%20Pin%201/2&category=%5BTechnic,%20Pin%5D#T=C

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  • Home
  • Wanna Build This?
  • 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
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      • 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
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    • Linkage Warm Ups >
      • Lever Paradox
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