Run Ralphie Run: A Mechanical Buffalo (Final Report Part 2)

How did it turn out?

Overall, I’m pretty ecstatic with how this project turned out. Amazingly, my scope and vision turned out to be nearly identical to my initial idea and conceptual design. However, the way that I executed that vision (internal components) turned out to be quite a challenge and rather unexpected. I ended up opening a can of worms I didn’t really want to open, but I’m extremely glad that I did in retrospect because I learned some really valuable things to take with me to future projects. Gear design is crazy.

Lessons Learned

  • Gear design is crazy. More specifically, getting 3D-printed gears to actuate things the way you want them to is a huge challenge, especially when you are implementing gear teeth onto parts that are not circular. But now, I know how to do it. That rocks.
  • Sometimes, there’s no “easy way out.” The other designs I considered for actuation other than gears were total garbage and would not have worked with any sort of consistency.
  • Your least engineered part is most likely going to be the part that makes your device fail, no matter how menial it may seem.
  • Tolerances for FDM-printed parts need to be very loose otherwise things won’t fit together. By comparison, machining is *extremely* accurate.
  • Corners must be filleted, especially if the part bears transverse loads about the corner.
  • No scope creep – set a realistic goal and attain it with due diligence!

Next Steps

  • Upload to Thingiverse with .stl files, a video and a small assembly guide. Hopefully it draws some attention (fingers crossed).
  • Design a stand for it since it doesn’t stand upright on its feet. I’d like to put one on my mantle.
  • Make a larger version with smaller gears. This should clear some additional space inside the box for more gears. I want to make the tail and the head move as well. Most likely, these will require different gear ratios, so this design change will be a solid challenge.
  • Design a version that can be waterjet cut from aluminum and uses fasteners. It’d make a fine present!
  • Make a version with a model of an actual buffalo rather than the CU logo. Long term challenge for sure.
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3 Comments. Leave new

Rachel Grosskrueger
April 30, 2016 8:26 pm

You definitely seemed to have taken some very valuable lessons from this! I’m still super impressed that you were able to design gears and make them work so well! I feel like this is going to be a hobby for you now that you have the basics down (and hey you have your own 3D printer so why not!) It would be super cool to play around with different themes/designs and really just go for bigger and crazier things!

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Ryan Yankowsky
April 27, 2016 12:33 pm

The project turned out great, the legs move smoothly, the gearing/ gaps for clearance really demonstrate how difficult gearing can be in modeling/ production. Did you load the design to the web yet or are there more iterations to come?

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They DIY aspect of this project is great. Future engineering buffs will jump on this for a desktop toy. Just out of curiosity, now that you have created prototypes could you lower the profile?

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