CONSTRUCTION BLOG
Mar 10th, 2018
I am currently working on a entirely 3D printed R2 Astromech. Since 3D printer technology has come a long way, and buying printers is getting cheaper by the year, I decided to take on my most challenging endeavor yet.
So a little about what I am doing…
This will be a completely 3D printed unit, minus the electronics (motors, boards, sensors, etc.). 
I will be attempting to incorporate a mini ITX motherboard, GTX 980 series graphics card, Intel i7 K series processor, 16 GB DDR4 RAM, liquid cooler system, and respective power supply into this unit as well. Figured that I should try to make use of the large internal volume of the Astromech unit.
This will be driven by a Raspberry Pi microcontroller, that will take advantage of full features of the astromech. (Retracting/Extending the middle leg, turning the head, reading and interpreting sensor feedback, etc.) The idea to create a autonomous control system that could ideally allow this droid to freely stroll around a convention floor and not come across major issues. (Of course we all know these desires are next to impossible to achieve, but that won’t stop me from trying).
Now onto the design process and a little explanation of how “I” plan to make this bad-boy work…
This will use a process I like to call An “Iterative” design process. This means that I will design and model sections or “phases” of the droid as I move along. Then, I’ll start to print, sand, and assemble. Based off of how the assembly works (because lets be honest, as far along as 3D printers have come, they are still not perfect), I will then continue to design the droid based off the discrepancies I encounter as I assemble this monster.
Recently, I have a procured a Lulzbot Taz 6 3D printer. Which has a very large build volume relative to many other 3D printers in its price category. This will serve advantageous to printing a large chunk of the parts while I sleep and report to my oh-so-enjoyable full time job (no pun intended).
I am using Solidworks 2016 as my modeling powerhouse for this project…
My next post will begin the discussion of the process…
Mar 11th, 2018
Modeling modeling modeling…
So my first “phase” of this Astromech unit is of course going to be the body chassis. But wait, i’m getting too far in front of my train of thought.
Let us look at the what you all have graciously provided to me to aid in the design…
Ah, CS-R CAD, this is perfect! Let’s go ahead and use the ol’ measure tool on Solidworks and model this sucker.
I’m gonna start with just the frame. Its the largest and most important piece of the entire droid, so if any catastrophic errors happen, at least it will be early in the process.
So after sprinkling some magic powder, BAM!!
The frame is in orange for your viewing pleasure.
If you take a closer gander, you’ll notice that I found some models of PC components and started to play around with how I can fit it into the droid. It’s looking like PC integration can actually happen. How exciting!
But wait a tick!?!
There is no way I can fit this entire frame onto my fancy printer’s heat bed, let’s break it down and make each split 3d printable (gotta watch for the 60 degree rule on overhangs T.T).
5 clicks and an Imgur upload later…
For your reference, this is one corner piece of the overall frame, I have parts like this that cover the entire frame of the droid (but that would be TOOOO many pics to upload on a single thread post)
So let’s go ahead and lay these suckers down on the printer and get that puppy working.
Well, that looks promising.
Now did they make it out of the printer?
PRESTO!!!!
Other than some rough edges (due to those dangs supports) that will need some heavy sanding, I think this is gonna work.
Stay tuned for more posts by me, I hope to dish these out on a regular basis, but I have a highly demanding full time job that requires me to take business trips for extended periods.
Let me know if this intrigues you, if so yay, if not, well what do you want me to do?
Jun 20th, 2018
A quick update for everyone.
The printer has been hard at work with getting the frame printed. I am about a third of the way finished with printing the frame structure. Once that is complete, I’ll be acetone smoothing and acetone welding the parts together.
So show y’all how the structure looks, I “loosely” placed some of the lower pieces together. Let me know what you think.
Oct 10th, 2018
Sorry for the extremely delayed response everyone.
I have been very busy with work and traveling all over the place. This makes crafting an Astromech a little challenging.
However, I have been assembling together the droid’s frame finally, while also beginning to design the mechanisms to actually drive the droid.
The first big update is…
I switched to PETG!
I found that printing with ABS really just is more work than it’s worth. Unless I build an enclosure for the printer, my part will warp like a mofo.
So PETG is much easier to work with, and holds fantastic thermal and structural properties.
So besides from that, here is a picture of the frame being assembled. I’m about halfway done with the frame of the Astromech’s body.
I’ll send another update as soon as I finish the frame. I have been hard at work with printing and getting the frame made. I hope within the next week I’ll have the next update.
Oct 18th, 2018
I just finished printing all of the components that make up the primary body frame of the droid.
Now that this major milestone is complete, here is what my forward steps are…
Printing the lower structure of the body, essentially the area where the third leg will drop down below from.
Then, after that structure, I’ll proceed to printing the dome structure of the droid. I just started modeling this part of him, so it may take some time to figure out what mechanism and method will drive the dome movement (I have to be careful of wires, other mechanisms, inertial mismatch, etc.)
Anywhoooo, here is where I’m at thus far in the body CAD. More to come!
Let me know what y’all think, I’m glad steam is finally rolling on this again!
Oct 29th, 2018
Hey guys,
Been printing like nuts lately. So its gonna take time before I start to show some more physical development. Here’s the bottom of the body for R2.
However, I have been modeling a lot of the animation that will drive the head.
To do this, I started by floating in motors, large components, etc. that I know will eventually be fully modeled into the droid and designate them as “keep-out zones”. These are there so as I model the actual mechanisms that drive the animation, I don’t collide with critical components.
More modeling and printing pics to come soon!
Nov 2nd, 2018
Starting to figure out what types of motors I’m going to use for this bad boy. I think I’m going to use Pololu motors for this droid. Now how many functions am I going to use? Well…
Head Turn – LG
Left Leg Fold Fwrd/Back – LG (Possibly LA – LG)
Right Leg Fold Fwrd/Back – LG (Possibly LA – LG)
Center Leg Up/Down – LG
Left Ankle Roll – MD
Right Ankle Roll – MD
Center Ankle Roll – MD
Left Wheel Fwrd/Back – MD
Right Wheel Fwrd/Back – MD
Left Rocket Open/Close – Servo – MD
Right Rocket Open/Close – Servo – MD
Periscope Up/Down – MD
Periscope Left/Right – SM
Antennae Up/Down – SM
Utility Arm Open/Close – SM x3
Tool Arm Up/Down – MD
Tool Arm Rotate – SM
Tool Arm In/Out – LA – SM
Eye Up/Down – Servo – SM
Eye Left Right – Servo – SM
Panels – Servo – SM x25
So in total that’s 48 functions that I plan to use for this bad boy.
Holy crap this is gonna be a controls nightmare.
*Cracks Knuckles
Nov 5th, 2018
Hey guys, new update here…
I’ve just finished installing the lower base of the frame assembly for the Astromech droid. Below are some pictures of the frame assembly…
I also started printing the dome as well. It’s gonna be a bit before I get him completely done.
As a matter of fact, it’s gonna take so long to print the dome, that one of the many parts I gotta print took 24 HOURS TO PRINT!!!!
Let me know what y’all think. Right now I’m putting together a spreadsheet to find the torques needed for my functions, then pair those functions to motors and calculate energy requirements.
Stay tuned!!!!
Dec 2nd, 2018
Update time!
Its been a while since the last update (being out of town in LA and the Thanksgiving Holiday kinda put this all on hold).
For starters, let’s talk about motors…
I have decided to commit most of my motors to Pololu. They seem like great motors that come packaged with both gearboxes and encoders. Perfect for what I need on this build.
And to be honest, not too bad pricewise for each motor. Considering the fact your getting all necessary drive components with each motor.
To make sense of how much madness is going on with this build, I’ve compiled a spreadsheet that details each animation function that is planned for this build. Meaning lots of power calculations and mechanical analysis.
Below is a screen cap of the Mechanical tab of the spreadsheet. This tab calculates the moments of inertia and the required torques of each motor per function based off some assumptions I made with a 2.5 FOS (Factor of Safety). It also calculates out price per motor and gives me an estimate on much financial damage I will be succumbing my wallet to.
Later on I will add an Electrical tab for power requirements and a Controls tab for Raspberry Pi and logic breakouts.
Boring spreadsheet stuff aside, lets move onto some really cool stuff.
Since getting back from business trips and the like, I floated in several aesthetic components making up a majority of the body for the Astromech. Several of these components will have to be modified to properly fit within my design of this droid. Mostly getting fits with the 1 inch thick frame.
Once I floated in these parts, I got a better sense of what’s to come next with aesthetic design, but I’ve been feeling pretty lucky today, so I got my first bit of animation about 90% done. Check. This. Out.
This is the preliminary design I’ve conjured for the utility arms of the Astromech. I would have preferred to use a direct drive for the SG92R servo, but based of the CS-R CAD, there was no way in hell I was gonna be able to make that fit properly. So a double linkage mechanism was made for each arm.
Considering how small the shafts are for each utility arm, I’m taking assembly and maintenance into strong consideration. So I’m working to get the mechanism and housing assembled with fasteners rather than glue in the possible event that something breaks.
I am also working to install hard stops on the mount for the motor to prevent homing from damaging the aesthetics of the droid. Because I know that these motors will need to be properly homed.
Anyways I hope that this post is both intriguing and informative to you. If you would like, I used CS-R dimension and weight estimates to develop my moment of inertia dynamic analysis. I can share with y’all my current version. Hell, if you see something up or just have any suggestions, I’m all ears. Pretty much going into this as a fresh set of eyes.
Cheers all!
Feb 9th, 2019
A quick update.
Its been a bit since my last update. Anyways let me show you all some more progress…
For starters, I created a simple mechanism to drive open the panels on R2’s dome. Below is some cool animation of these panels in action!
This design utilizes small servomotors to drive open the panels. Nothing too crazy here, taking a lot of inspiration from previous design on this.
Now the legs…
The legs are fairly unique in their design. I created a fairly unique shaft driver that allows the small shaft from the Pololu motor to drive the large mass of the legs into their 2-3-2 configuration movements.
I still have a lot of work to do (in terms of sizing, fitting, ensuring it works). But this is not bad with a first pass in design.
Here is the overall view of R2 so far, he is getting a little crazy.
I hope this design work is interesting to y’all. Hopefully soon I’ll get more actual 3D prints in to show off the physical side of the build more.
Cheers!
The Technological Exploits of Erik Ballesteros 