I finally built up the courage (and funds) to attempt an R2-D2 build. This was, by far, my most extensive (and expensive) robot build to date. The total effort took a full 9 months including planning, fabrication, painting and assembly and cost was more than $5500 (and still climbing). I learned several new skills during this build and found it to be very rewarding. All the while, feeling enormous pressure to faithfully reproduce this iconic robot.
In truth, this build was a series of concessions. My skills, tools and selected material did not allow me to truly achieve a perfect replica as I had hoped. While close, when I look at my latest creation, I see thousands of tiny imperfections that I hope to remedy someday.
The R2-D2 Builders Club (aka Astromech.net) has a library full of useful content that was leveraged during this project. The site is filled with plans and reference pictures. However, most useful were the forums where I was able to learn from the success and failure of others, and also ask my own questions. I found the community to be very friendly and open to sharing their experiences.
The body parts were cast using a binary urethane resin. Wood core was added to some of the load bearing parts for strength. The parts were cast, cleaned and primed over a period of about 6 months. Most parts were cast separately to allow for easier painting before final assembly.
Mechanical parts such as the foot drives and the neck were bought, rather than fabricated to expedite the process, ensure good quality and accommodate my lack of skill (I’ve never learned to weld metal).
Painting was done mostly with spray cans recommended by the R2-D2 builders club. The most challenging part was the “blue-ish” colour. This was the result of 7 layers of paint including metalic base coat, 3 layers of translucent purple and 3 layers of blue – the result is a wonderful cobalt blue that changes in different light. Finding a good masking tape was key to avoid rework because some of the stickier tape lifted paint off when being removed. I settled on low-stick tape from my drafting table which worked better than anything else I could find.
Assembly of the parts was mostly done with E6000 glue which is wonderfully forgiving. I had originally intended to use Zap CA+ glue, but found it to be quite dangerous to use as it somehow kept finding its way onto my skin, and required painful measures for removal. Key hinges such as the ankles and shoulders used heavy duty bolts to provide the strength required to properly support the unit.
To really bring R2-D2 to life, I knew I had to do some great stuff with electronics. I started with a Taranis X9D controller and a pair of X8R receivers configured for a full 16-channels. I chose this platform mainly for its versatility, but also because I wanted to have separate control of the head and body with one remote controller (so the head can spin a full 360 degrees without tangling the wires).
Through the remote control, I control the following:
- Pair of foot drives to control movement (skid steering configuration with the left control stick)
- Trigger playback of sounds from a MDFLY MP3 board
- Dome spin (driven from an Arduino Uno with a Ardumoto shield)
- Move the front holo projector (with the right control stick)
- Activate a lamp inside the front holo projector (driven from an Arduino Pro)
Ah, but I have sooo many unused channels! I need to keep thinking of new features to use them all.
I’m especially proud of the front holo projector movement platform that I fabricated. I used my X-Carve to custom-cut the required holes in some HDPE plastic sheets to get the exact placement required. I mounted 2 servos (one for X axis, one for Y axis) that maneuver a bolt fixed onto the back of the holo lamp. I chose a pair of Hitec micro servos that had a good balance of performance and size. I had to do some clever trimming to get it all crammed into the head taking care to work around one of the dome lamps.
For the body, I started with a 10″ x 10″ perf board and strategically mounted the required components. I used a 2×25 Sabertooth for the foot drive motor controller. The MDFLY, Adafruit Class D amplifier circuit and Arduino boards also got mounted onto the perf board along with the X8R receiver. I custom built the circuitry to provide the voltage levels (12V, 6V, 5V) for the various components. A lesson I learned from my K-9 build, I added a fan to help keep the Sabertooth from overheating.
I powered the body with a Deep Cycle 12V sealed lead acid battery with 14Ah which will hopefully let me last a full 8 hours of moderate use. I felt this was a good compromise of capacity and weight. I powered the head with a 9V battery (LEDs, Arduino and X8R) and a separate 4xAA battery set for the servos.
Ugh, sooo many challenges. Where to begin…
- My painting skills were quite poor before I started this project, and I improved with practice. However, the learning curve was steep and expensive. Lots of re-work on painting was required. Finding the discipline to avoid painting during days with high humidity was especially difficult for me, and it shows in the final result.
- I put the foot drive motors in backward. As it turns out, R2 likes to run on the front of her foot, and not the back. After full assembly, I had to re-cut and re-install the foot drives to allow it to move.
- The dome spin is still quite vexing. It uses a large lazy susan with a small drive motor and a foam wheel. Unfortunately, it is not a gear motor, and generally lacks the torque to spin the dome. Lubrication of the lazy susan helped a bit. I will need to revisit this soon.
- Clearcoat was a must for me so I could avoid paint wear, provide some protection, and have the ability to easily wipe down the droid before bringing her into someplace like a hospital. Unfortunately, some of the paint I selected (especially the chrome) had a really bad reaction to the enamel clear coat. After much experimentation, I ended up using a clear glossy spar urethane spray. It does slightly tint the color, so I can’t use it on any of the white parts, but it does a good job of protecting without changing the color.
- Transportation – I’m still trying to figure out how to get the droid out of my basement. It is both heavy and cumbersome. Also, there are not many good places to grab and lift without risking pieces falling off. A full enclosure with a padded interior, wheels and a door was recommended for ultimate protection during transportation, but that will take quite a bit of engineering.
- Warping of the resin parts – I ended up having to buy very large worm drives and putting them insider the body to provide “ribs” to help counteract and prevent further warping. I also spent a lot of time heating and gently coaxing the resin back into place.
Just the beginning…
My overall goal with this R2-D2 is to showcase it at cons and events so others can enjoy it. I think mine is durable enough that I’ll be able to attend lots of events. I really hope she makes lots of kids (and adults) very happy. It’s also a great platform for future growth and expansion to start to use all those extra RC channels. I’ve got a long list of features I want to introduce in the future. This could keep me busy for years!
Welcome to the family, R2!
Astromech.net Builder Page: http://astromech.net/droidwiki/User:Bithead942 (Login required)