VI:  R2-D2’s Arms and Tools

I suspect that’s because the interior was simply open so that Kenny Baker could operate the arm from inside. Sometimes, in the case of ANH droids anyway, the back panel may have been left off, and a technician just held the arm through the empty body.

There are two times in the Original Trilogy when compartment interiors are sort of shown: Yavin 4 and Dagobah.

ANH: The interiors of R2’s compartments are almost, but not quite, visible in the split-second moment when he's lowered from Luke’s X-wing following the Death Star battle. Various bits of wire and scrap, along with black paint and other damage effects, were applied to one of the two-legged R2 props for the sequence.

Here’s one of the behind the scenes photos which tantalizingly hints at what the prop makers did to decorate the interiors. They clearly put in 1970s-era printed circuit boards with discrete components and IC chips into two compartments, along with coiled bits of coloured wire and maybe some ribbon cables. Unfortunately, while there are several known B&W photos of R2 in this condition, in addition to movie colour framegrabs, sadly nothing has enough resolution to show fine detail. So the three exposed interior compartments are not really known to any real extent.

ESB: On Dagobah you see Luke plugging his “fusion generator” into R2. This “feed the dog” scene reveals a few flashing LEDs and nothing else - the rest of the port is in shadow.

Non-Movie Compartments: The lack of screen-seen compartment interiors has led to some interesting theorized internal designs used by both model/toy manufacturers and hobbyists.

The most commonly seen fan concept appears to originate from 2006's Star Wars: The Complete Visual Dictionary. This rectilinear light and panel design for the large compartment on the left side of R2's body has become known by the R2 builder community as the “data port.” I believe it was designed by Don Bies. Michael Baddeley's 3D-printed designs include it, dramatically increasing its popularity.

A few years later a different design for the same compartment was included in the 2010 book Star Wars Blueprints: Rebel Edition; a childrens' book illustrated by Chris Reiff and Chris Trevas. Chris has said that he based the compartment details on the location of film-seen tools and arms, and also earlier work by Mike Verta. You can see, for example, how the right compartment, harmonizes the zapper (ROTJ) and charge socket (ESB) functions. Several commercially available R2 products (Sideshow Collectibles, Bandai, and De Agostini, for example) have subsequently modelled their compartment interiors after this design.

The De Agostini R2-D2 kit has these interiors, clearly copies of the Rebels Blueprints design. They seem to have missed some key points in Chris’ drawing - that the big round thing on the left is a socket for interchangeable tools and not a flat disc, that the small round thing on the right is a recessed socket and not a raised detail, and most goofily, that the the ovoid with a cross isn't a grid-like thing, but the zapper tool from ROTJ seen end-on.

“Two men say they’re Jesus; one of them must be wrong.”

– Dire Straits, Industrial Disease

Incidentally, these drawings are not the same as the blueprints used to make the original props. The production drawings don’t show the compartment interiors, and look like this one, reproduced in J.W. Rinzler's Star Wars: the Blueprints:

ROTJ: A cheesy comedy moment occurs when R2 plugs into a power terminal during the bunker assault sequence. He’s shown spinning around wildly, all hatches open, with various accessories protruding.

Though one interesting fact that I never noticed when I first saw the film - in this scene, poor R2 actually wets himself. Yikes.

The Special Edition makes this scene even less likely by digitally adding various new tools, and having smoke or steam emerge from improbable locations like the holoprojectors. There are lenses in those projectors! How is smoke supposed to come out of them? Note also the famous R2 Magic Panel, which is glowing red in this shot despite being a metal door in most of the film.

The SE also removes the pants wetting. So it's either bowdlerized or a sophomoric immature joke has been removed, depending on your point of view!

Door interiors

ANH: Only the outer tall doors’ inner surfaces are visible in the film, and they're simple flat bare metal with a couple of rivets.

ROTJ: The doors seem to be one-ply metal, not two-ply like above.

Interestingly, there's a red sticker on the interior of the zapper/charge bay door, seemingly covered with white Aurebesh (the fantasy typeface used in the Star Wars universe since 1983, or 1993, depending on your point of view).

Prequels: I don't cover the prequels fully in this section, but this is one useful thing of note. This back door interior design was used in Episode II, when R2 fires a magnet-tipped cable to collect C-3PO's head. So it's not in keeping with the Original Trilogy, but the pattern is more interesting than the blank metal used in the OT.

The silver door

ANH: As discussed in the previous chapter, many scenes in ANH show a grey, or maybe silver-painted or bare aluminium, panel on R2’s back. Other scenes show an R2 with all-white back panels. No other film has anything other than white back panels.

Computer download interface

ANH: R2 is seen connected to a computer by a technician so the Death Star plans can be downloaded. Oddly, the interface cable is shown being attached to something obscured by his body - over his right shoulder, or somewhere. Maybe the right door?

It’s like they didn’t quite think this brief scene, which was shot in California towards the end of production and not on the English sound stages, entirely through...

ESB, ROTJ: Not seen.

Blue utility/manipulator arms

ANH: As described in the previous chapter, one of the oddly-shaped blue zigzag features, often called utility or manipulator arms, is seen early in ANH. The one in the escape pod corridor scene is solid with serrated ridges on the inside tip. It's blue throughout, including the inner surface.

By contrast, this promo shot of the radio-controlled ANH R2 (ie: this isn't one that Kenny Baker could fit inside) shows a droid with bare metal inner arms. The photo also shows how the ends of the arms on the RC droid could rotate. Or at least be rotated.

ESB: The blue arms have the same ridges on the inner end that the ANH arms have. The interiors of the arm recesses appear to be white.

Chess manipulator arm

ANH: Seen briefly in a long shot during the Dejarik/holochess scene. This is a double arm with three straight pincers at the tip. Housed in the left-hand tall compartment, it appears to be the same arm seen on the “binocular” Treadwell droid. That’s the robot that’s seen briefly in the Sandcrawler droid prison (head only), and the deleted scene of Luke in his Gilligan hat next to a moisture vaporator.

Incidentally, the pincers are a found object. They're simple kitchen tools sold as ice cube/pickle grabber tools. And they're still sold today, if you want make your own full-sized R2-D2 Dejarik arm!

ESB/ROTJ: Not seen.

Computer interface arm

ANH: The aluminium rod that R2 uses to talk to strange computer terminals is shown in some detail in the film. It has recessed grooves at the movable end, with small details on the sides of the truncated pyramidal tip which are nothing more than ordinary wires and resistors. There seem to be two brown higher-wattage cylindrical resistors , and at least one pale grey lower-wattage resistor. Screenshots from ANH suggest that the arm may have had a resistor in the fourth position, and a photo of the prop taken years later seems to show two grey resistors.

Brown cylindrical: orange/orange/red/gold, so 3.3K ohm with a 5% tolerance.

Brown cylindrical: orange/white/black/gold, so 39 ohms at 5%.

Grey tapered: possibly purple/green/red/silver, so 7.5K ohms at 10%.

Grey tapered: possibly red/red/green/silver, so 2.2M ohms at 10%.

The main cylinder is also decorated with black, yellow, red, and white pinstripes, somewhat similar to those the hyperspace control levers on the Falcon, and red and yellow dots. These are probably thin vinyl tape lines – they aren't engraved. Conjecture: the arm was probably turned aluminium, designed and made for the film. One part at the tip is brass.

The rod swivels out to a horizontal position, and the tip emerges outwards on a steel rod. Note that it's fairly long. The original prop, when folded into the body, took up the entire length of the tall left-hand (or right-hand from R2’s point of view) compartment. (see the damaged R2 photo in the door interiors section above) The tip of the head has a small hole, about 1/3 the size of the diameter of the end.

Sometimes this arm is referred to by fans as a “scomp” interface. Not sure why. They're possibly borrowing the name from the Honeywell "secure communicators processor" technology used by the US military in the 1980s.

ESB: The same basic arm seen in Star Wars emerges from the same compartment, but it's missing most of the pinstripes and all the dots. It now emerges from the bottom of the compartment rather than the top. Conjecture: the set designers made the computer interface on the wall without realizing that the arm wouldn't line up at the same height as the Star Wars computer interfaces, so the prop people had to lower the arm position. It seems to be missing one of the grey resistors in this film.

So how did it lose its lines and dots? Conjecture: I don’t know for sure, but I’d guess that it’s because of the battle damage scene. The computer arm is visible inside the R2 that’s lowered down from Luke’s X-wing at the end of the Yavin hangar sequence. A lot of black paint was splashed around the interior to make poor R2 look even more beaten up. Now, assuming that this scene (filmed at Shepperton) was done after the Elstree-filmed Death Star scenes, perhaps the black paint went all over the vinyl pinstripes. Then, when it came time to film Empire, they had to strip off all the paint from these detailed parts. And this ended up removing all the pinstriping. The ESB arm has just 4 lines on it, and some seemingly embossed material.

ROTJ: Our old buddy makes a final appearance in the trilogy in Jedi. With even fewer pinstripes than in Empire. Those stripes just keep on falling off! It’s interesting how much more oxidized and dull the whole thing looks by this film. Two ordinary Earthian resistors are very apparent in this view.

Prequels: The original trilogy arm is physically different from the Episode II arm. The prequel arm tube has engraved lines on it, filled with paint, in positions roughly similar to the ANH arm. However the head is completely different, and looks like a piece of aluminium that’s been CNC-engraved. The engravings have been filled with coloured transparent paint, and there are no wires or resistors. There are closeup views of the two arms in question on Astromech.net.

Grabbing arm with curved pincers

ANH: Not seen.

ESB: A small slender arm with two curved pincers emerges to try and retrieve Luke’s light from Yoda’s clutches. Published blueprints show that it had a telescoping inner tube attached to an internal pivot to allow the pincers to move.

You don’t get a very good look at it in the movie, so here’s a shot from Star Wars: the Complete Visual Dictionary. It seems to show the same grabbing arm, along with some conjectured descriptions of the prop's components. The lower arm is the zapper from ROTJ.

This arm appears to have migrated to another compartment in this video, incidentally. Still, R2 is skulking behind the bike racks, so who knows what trouble he's been up to? Here's a closeup view on Astromech.net, and here's another.

ROTJ: Briefly glimpsed during the open-doors scene.

Charging port

ANH, ROTJ: Not seen.

ESB: Luke is seen plugging a surprisingly long plug with a spiral cord into R2 to charge him up. The socket is inside a small compartment on the front. A lot of people refer to this small compartment as the “charging port” for that reason, though sometimes people call it a “zapper compartment” since the taser-type zapping device emerges mysteriously from that compartment in ROTJ.

Manipulator/hyperdrive arm

ANH: Not seen.

ESB: An arm with three angled pincers, and four small lights, is shown plugging into a power terminal by mistake on Bespin. The same arm is used to hold the welding torch that R2 uses to repair C-3PO, and also to engage the hyperdrive on the Millennium Falcon. (ie: the welding torch isn’t part of a separate arm but simply this arm holding a miniature torch) The washer-like rings are quite misaligned, which is an interesting detail.

The arm appears to emerge from the middle of the right-hand door during the the Bespin scenes, but definitely protrudes from the middle of the left-hand door during the Falcon repair scenes. Its lights aren't on in the Falcon scene, though.

Note one interesting and obscure detail – the rod to which the pincers is attached isn't a standard circular cross-section rod. It's actually an X shape in cross-section. I wonder where they found this, as I haven't been able to find commercially available X cross-section rods like this anywhere.

ROTJ: Not seen. I think.

Zapper

ANH, ESB: Not seen.

ROTJ: A small arm pops out, strangely enough from the charging port area, to slice through Leia’s chains and to zap the pesky Salacious Crumb with some rotoscoped lightning. R2 later reuses it to zap an annoying Ewok. As noted above, oddly this arm emerges from the area where Luke plugged the power cord in Empire. However the compartment interior is in shadow, so we don't get to see anything there.

There’s a closeup view of a zapper on Astromech.net, but it looks different from the one above. It's similar in key areas, however, so perhaps it was permanently altered for Episode II or something like that.

Incidentally, the key part of the zapper has now been identified. The dark grey rectangular bit was the internal frame from a large electrical toggle switch. The same thing was used to create the intercom microphone that Lando speaks into when warning the citizens of Cloud City.

Welding torch

ANH: Not seen.

ESB: An noted above, an arm and welding torch is shown briefly as R2 works on C-3PO’s foot in the Falcon's hold. You can see that the hyperdrive pincer is holding it.

ROTJ: A welding torch is also seen on Dagobah as R2 works on Luke's X-wing in Jedi. It’s pretty dark, and it's not easy to tell from the angle where it's supposed to be coming from, but it seems it's meant to be on the left side of R2's body. I've brightened the images below, but they're still rather murky. Still, it appears that this may have been a whole new tool rather than a grasping arm holding a torch, as in ESB.

Adding evidence to this theory is this image below, from Star Wars: the Complete Visual Dictionary. The author has theorized that the prop is a “lubricant applicator arm,” but it’s quite clearly the welding torch seen above. There’s also a great high-rez photo on Astromech.net

Circular saw

ANH, ESB: Not seen.

ROTJ: A small circular saw emerges from one of the central panels during the Ewok trap scene. The compartment is in shadow.

There’s a closeup view of what purports to be this saw on Astromech.net.

Dome manipulator arm

ANH: A very slender manipulator arm, somewhat wobbly, emerges from R2’s head during the Death Star battle. This is kind of a strange one, since it’s way too long to fit inside the dome, but it has no evidence of telescoping sections - it’s some sort of magic stretching metal, I suppose. The tip is reported to be an old-style Griffin and George “Microid” lab clamp for holding bottles, test tubes, etc.

ESB/ROTJ: Not seen.

Fire extinguisher

ANH: A narrow gout of fire-extinguishing spray is seen coming from R2’s head. A brass nozzle appears to be screwed into one of the small blue panels on the dome below his eye, but this mystery nozzle is never seen in any other shot.

Artoo valiantly extinguishing a fire aboard the Falcon, though apparently without the benefit of proper fire training since he isn't aiming the chemicals at the base of the fire. Note also a fun thing over to the left. You can see there's a big hole in the battery box attached to his left ankle. This is probably because the Kenny Baker two-legged R2 was used, and the hole is where Baker's foot would go when he was inside the prop. The three-legged droid also had this hole, but it was covered over with a metal plate.

ESB: R2 produces a thick blanket of fog to obscure our heroes’ escape from Bespin. We aren’t shown where the fog comes from, but it’s somewhere on his head or his upper body.

ROTJ: Not seen.

Lifeform scanner

ANH, ROTJ: Not seen.

ESB: A curved metal antenna grid appears from R2’s head on Hoth. Like many R2 accessories, it has an improbably lengthy support rod for something that supposedly fits inside his dome.

There are high-rez photos of a lifeform scanner on Astromech.net, but they look quite different from the one in Empire shown above. Perhaps it was made for some other purpose, or was used in Episode II? I have no idea.

Periscope

ANH: Not seen.

ESB: An entire wedge of R2’s dome pops out and serves as a periscope after R2 falls into the Dagobah swamp.

ROTJ: The Empire periscope returns, poking up from behind a dune in a particularly phony-looking moment. We therefore can’t see if it’s coming out of the same pie wedge or not, but model makers get a good look at the design.

Astromech members can access this terrific photo library of shots of this prop. I only wish the images were bigger!

http://astromech.net/gallery2/main.php?g2_itemId=49308

Light sabre ejector

ANH, ESB: Not seen.

ROTJ: A panel retracts in a strange way (it doesn’t flip back) from the top of R2’s dome, so a powerful ejection mechanism can hurl Luke’s light sabre into his hands. Note also a strange continuity error in this scene - the sabre's business end is both chipped and missing any sort of hole from which the laser energy is supposed to emerge!

Drinks dispenser

ANH, ESB: Not seen.

ROTJ: An external drinks dispenser mechanism and cupholder is seen protruding from his dome during the start of the sail barge scene.

It looks like it’s supposedly an add-on and compatible bit of machinery, however, not something normally built into him. The top disc on the dome is shown flipped out to accommodate the dispenser.

The Prequels

I don’t cover the prequel R2s in full detail here. Many of the droids were partially or entirely CGI in nature, and there are a lot of unlikely antics that don’t even seem to be physically possible, such as flying around on leg rockets.

Of course, these films do continue the tradition of not much continuity. For example, the computer interface arm is shown again in Attack of the Clones, but it pops out of a left-hand compartment and not the long right-hand one.

On to part VII: Other Astromechs

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