A working Computer Interface Arm…

For a while, I’ve really wanted to make a working “computer interface arm”. I had one made in aluminium a while ago, but this proved to be way too heavy for my styrene droid, so I decided to sell it.

When looking at the movie, R2 “flips up” his arm, then the tip extends, and it rotates as it is inserted into the computer interface.


Image from (c) LucasFilm / Disney.

Most likely, this is accomplished by some sort of magnet lock, and it is actually the wall panel that rotates, and the tip of the interface arm only “tags along”. It is a hundred times easier to make, and this was after all done in 1976, so most likely, That is what happened.

That is not what I’m planning. I’m planning to make a computer interface arm that can both extend AND rotate!

I plan to accomplish this through a simple method:

The thick part of the interface arm is a hollow plastic tube. The tip is 3D printed and mounted on an aluminium tube.

This tube is inserted into a smaller aluminium tube that is fixed within the hollow plastic tube with 3D printed parts.

Inside the aluminium tube, I mount a stiff cable on a holder from a tackle shop, that can rotate as much as it wants.

The stiff cable goes through the assembly to the back end, where a servo can either push out the tip, or retract it. Pretty much the same way an electric car antenna works.

The tube in which the cable resides, has gears glued on to it, and can through a 360 degree servo rotate in either direction. The stiff cable inside, which controls the extension/retraction movement is still in place, and the small tube with the tip attached to it, rotates around it.

Sounds complicated, and to some degree it is: Have a look at these images and see if it makes more sense:



These pictures have the rear servo taken out for clarity, and also the inside tube removed for clarity. The inside tube would have slots cut out to make contact with the outer gears.

Now that my 3D printer is upgraded and make better parts than ever, it is time to set this all into action! 😀 Stay tuned!

By | August 25th, 2015|R2-D2|Comments Off on A working Computer Interface Arm…

Side speaker mount done!

Quick update.

I drilled the metal brackets holding the new speakers, coated the inside of the “pockets” where the speakers will reside with black felt..


.. and hot glued the perforated aluminium backplates in place.


I might need a little more hot glue, but that is a minor issue, as I can always add that later on.

Finally I decided to hot glue the metal brackets in place as well, as I really don’t need to bolt them in to place at this point just yet. It is difficult to drill through inside the body, and the industrial strength hot glue is good enough to hold them in place. If not, I’ll just gently pry them lose and replace the hot glue with E-6000 once I get a new fresh tube.


After trying to fasten the missing hatch in the front, I needed to adjust the hinge somewhat, si I snapped it lose (it was only superglued into place after all), tampered with it slightly, and glued it back in place with the last of my E-6000. That should hold it firmly in place!

As a final thing, I had to test it, and naturally, I can get quite a lot of volume out of the droid. I could still do with more bass, so who knows… Maybe it’ll be a low end speaker or subwoofer inside at some point.. make sure everything inside rattles lose 😉

Once the tests were done, I also had to try out the freshly made driving sound. I recoded this over Christmas at work from one of my colleagues electrical re-positionable desk and worked with the sound file late last night.

Now off for an early evening. Last night of building for this time around tomorrow. Who knows, Maybe I’ll get around to switching the drive train to the one I fixed a few weeks ago. I’m still driving around with my old scooter motors, rather than my newer, fancy twin Jaycar direct drive system…

By | May 12th, 2015|R2-D2|Comments Off on Side speaker mount done!

Almost faceplant, repairs and small upgrades…

I took R2 out a little while ago, since there was a huge Star Wars fan at work who was leaving the company, and I decided to bring R2 and make his day.

On the way there, my small cart that I pulled R2 on, came to a full stop, and R2 plummeted forward.. was I finally going to have the dreaded face plant? On a gravelly city street none the less? *gasp*

Fortunately my lightning fast reaction managed to save the droid before the front hit the mix of gravel and tarmac, but not without battle damage. The tiny door around the charging bay panel took a hit. The hinge was bent, and the door was broken off in two places. I was lucky I found all three parts of the hatch to begin with!

I got through the day (and a subsequent official Disney / LFL event) by adding a bit of scotch tape… first to hold the panel together, second to hold it in place.


Yesterday was the day to start fixing that, and also to make some time for some small upgrades!

First off, I managed to get the hatch lose from the hinge inside. The hinge was bent beyond repair, as it is totally impossible to remove the hinge and correct it. It is one of those things that needs to be done before it is installed. I had glued the hinge to the inside of the robot using E-6000 glue, which turned out to be holding the hinge insanely hard. In spite of trying to cut it lose, bend it lose or pry it lose, it only resulted in me breaking the hinge even more. I took a sturdy pair of pliers and broke off all parts from the hinge sticking out, leaving only the “flat” part that was still glued to the inside of the skin. I would have to work with this and glue the new hinge on top of the old one…

So, for starters, there’s a gaping hole in the front of my droid. New hinge is not yet mounted.


At least I’ve got a straight, working hinge..

The hatch has been glued together with superglue.


Technically, I could build a new one, but the painting is a bit of a hassle when you live in an apartment, and getting the weathering to match might be even more so. Besides, the visible cracks can still be extra weathering and battle damage. I have even considered adding a darker wash to the crack to make it even more visible.

Next step: I took my front speakers and changed the way they were sitting in my amp. They wer just clipped in my amp, and one of the clips had broken lose, so I soldered the cables inside my already modified and soldered amplifier (see Octagon Volume Control) and added a proper, sturdy connector to be able to remove it easily:


I have also prepped a second amplifier, that is supposed to drive two speakers that will be sitting right inside my side vents.

So, since I was in doing things, I pried lose the back plates from my old side vents… and let some air in.


Next step: cut out and lightly bend new back plates out of perforated aluminium


In place, they are still see through…


But, with an added layer of black felt behind it, it should be invisible. I still need to add a bit of weathering to the back plate though.


At the moment, the idea is to mount speakers from within on metal brackets, and possible cover the white frame parts in black felt, and surround the speaker with black felt as well, creating a totally black trap behind the vent. It will create a little bit of depth, but also not showing anything of the frame behind the perforated plate. The plate needs to be perforated in order to let the sound waves through properly, of course.

These speakers


will be mounted on two brackets like this


on the inside. The brackets were made from aluminium and I broke off two of them before I realized that heating up the aluminium with my blowtorch REALLY helps when you need to bend it! =)

I also soldered the cables in place needed for the new amp and pulled out a power cord for it. Done. I still need to route out the second volume knob like I did on the first droid, but I will require a little help with that this time.

I also took out my Rogue Robotics mp3 shield, which is really old and have no updated libraries for my arduino since 2012, and resoldered the 3,5 mm socket back in place, it had broken lose somewhere. It works now, but it sounds like there is no volume coming from it. Fortunately, it is no problem for my amplifier!

A bit of updating and tweaking the sound code in my arduinos (The new panel with the USB connectors is SO great! Best idea ever!)


… and it is working a lot better. STill lots of things to mount and tweak.

Next step will be to program my new XBee and replace the old one in the transmitter. Not because it is faulty, but rather because of the huge antenna. It’s not like I need 300m+ range on my droid after all. The much smaller one has a more limited range, 100 meters in open terrain, but as long as I have a range of 10 meters, I’m more than fine. I never like to be away from my droid anyway …


That’s it for now… more shortly!

By | May 12th, 2015|R2-D2|Comments Off on Almost faceplant, repairs and small upgrades…

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