Project Logs

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• More Cycloidal Gearboxes

  Paul Gould • 03/15/2021 at 17:25 • 0 comments

• Strength Testing

  Paul Gould • 01/03/2020 at 12:47 • 0 comments

• Stronger Thigh Bones

  Paul Gould • 11/14/2019 at 15:46 • 0 comments

  I printed one at 95% infill and it is holding up ok so far. But before I print another four legs I wanted to make sure I made the first leg as strong as possible (with my cheap 3D printer).

  3D printed plastic is better under compression than tension.

  As the gearbox outer housing will be under tension, I wanted to preload the housing.

  Things I looked at

  • Carbon fiber / Nylon / PETG / PC filament
  • Making a groove and Stopping print 1/2 way into  the printed to insert steal wire or carbon fiber/ Kevlar tow. Using epoxy to make it rigid

  I decided on making grooves on the outside and putting yellow braided zero-stretch fishing line.

  As I didn't want the line to split though the 3D printed layers, I coiled the groves on a ~5deg coil angle.

  The line is tighten by twisting the line. May try two lines per groove.

  I will also try multi-strand nylon stainless lure line.

  End View
  

  Bottom

  CAD
  

  CAD end

• Broken Knee

  Paul Gould • 10/31/2019 at 14:26 • 0 comments

  I forgot to "zero" the knee before starting the inverse kinematic testing. It was the first day on the leg test jig.

  Gears have 85% ABS infill, housing has 50% ABS infill. I will have to add the joint absolute encoder back into the system.

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