Graham Likes To Make Things

FREELANCER • PRODUCT DESIGN • PROTOTYPING • 3D PRINTING
Product Design

Crazy Radio Controlled Walking Robot

This is by far my most favorite (and most time consuming) personal project, and the project I was most excited to get my 3D printer for.

I started working on this while I was still studying in University, after discovering Theo Jansen’s “strandbeests”. For those who are unfamiliar, check them out on YouTube! I instantly decided I wanted to make a radio controlled car that incorporated Jansen’s foot mechanism. As you may find on YouTube, there is already quite a lot of these – but none of them are fast, and lack functionality such as steering and suspension. I wanted mine to run fast and make lots of noise, with the usual features a radio controlled car has… steering, suspension, etc.

I had a Traxxas Revo 2.5 at the time, so I figured I would sacrifice it for a good cause, and use the necessary components to get started such as the engine, gearbox, radio gear, diffs and drive shafts. I wasn’t in the 3D printing loop at the time, so with my creative licence being limited to what I could achieve with a hacksaw, I got designing!

And here she is, the first iteration of the beast. I don’t know how far I got building it, but I soon got fed up printing out templates, gluing them to ply wood, and trying my best to cut them out. So I gave up and decided to start attending University again.

Years later, I graduated and got settled in a job and a new location. One day I was browsing the web out of boredom, and discovered these things called “3D Printers”. If you are like me, you will remember this moment too. The excitement, the realization that you can bring your ideas to life in the comfort of your own home, with minimal effort and no limits. I just had to have one.

Creative licence set to level 10, I got designing again. The goal in mind to make my robot look crazy awesome cool, a visual complexity where you don’t really understand what you’re looking at – but just looks awesome.

  

Many many months later here is the result. When I began I soon realized why all these robots incorporating Jansen’s foot mechanism don’t have steering or suspension – it’s not easy to accomplish. The foot assembly needs to pivot around a center point that just isn’t there. I didn’t want to have any parts hovering behind or on top of the feet as it would look bulky and horrible, so i was set on designing some kind of mechanism that best mimics pivoting around this virtual center point. This isn’t necessarily difficult, but I also wanted it to have functional suspension. I don’t really know why, I just did.

Anyway, let the printing commence!

  

Yes, that’s my phone taped to a kitchen roll tube taped to Far Cry 2. I started with the biggest part of the steering assembly first, estimated to take about 15 hours, I was keen to see if my printer was up for the job, and keen to get an awesome time-lapse video of it. At the time of building my robot, the Makerbot Replicator 2 was the crème de la crème of 3D Printers. It is now however quite outdated in terms of functionality – with no ability to detect nozzle blockage or any kind of problems what so ever, owners of this machine will understand the anxiety one gets when printing such a big part – especially when one needs to go to work leaving it printing for 9 hours unattended… I had many many nervous walks home while building my robot, not only hoping that the part completed, but that my printer didn’t also spontaneously combust and burn my house down. I have to say though, when I finally figured out how to treat her properly, I only had 1 failed part in 1000 hours of printing. Very pleased with her performance!

 

Several weeks later, and most of the steering mechanism is ready to be assembled.

Most the front chassis and steering mechanism built with gearbox and servos in place, time to build the feet and rear!

(…about 1 month later, and far too much money spent on bearings and gears)

(but totally worth it)

 

Most the essential mechanical bits are out the way now, just need to print and build the middle to hold the battery, motor and radio gear. Oh yeah, a little 2.5cc engine would have totally destroyed this thing. Not necessarily because of the power, but the engine would have probably melted its way through the robot if I fired it up, so I switched to a brush-less motor, besides – MORE POWER!

Simple as that. About half a year, hundreds of printed plastic bits, hundreds of hand made rods and shafts, and hundreds of bearings later, I has (almost) complete robot!

Unfortunately for me, it didn’t quite work. Well it kinda did, there is nothing really wrong with it mechanically, it could run a few feet but the steering mechanism would mangle itself due to the plastic just not being strong enough.

Not the end of the world though, it was certainly a fun exercise, and I will get round to making it work one day. I have some ideas and improvements in mind, and there has been some pretty decent advancements in 3D printing material since working on this, so I am confident one day it will run!

For now though, here’s a video of the steering mechanism at least.

All printed parts are printed with Colorfabb’s PLA/PHA, and I have to give Colorfabb credit for their exceptional filament. It may have been the wrong choice of material since the PHA blend makes it a bit more flexible than pure PLA, but it certainly can’t be faulted for it’s reliability, performance and finish.

Comments