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!