Here are the current (April 2001) specs to my R2

Designtion: R2-D2 (maybe an R2-D5 later)

Dome: Spun Aluminum (Dave E.)
Body/Dome Diameter: 18.5"
Dome Bearing: 17.5" Dia Rockler Bearing (local supplier)
Dome Spinning Mechanism: Unknown - Later added a 6VDC motor and 4" wheel
Dome Panels: For now surface painted, maybe later engraved
Holoeye: Droidboy - later changed to Dave E
Holoemitters: Droidboy - Later changed to Jeremy F
Radar: none for now
Sabre Launcher: none for now
Dome Red/Blue Light: none later LED unit
Dome Yellow/green Light: See above

Dome blue diagnostics: none later blue LEDs

Dome green diagnostics: none later Green flashing LEDs wired to the blue ones
Slip ring: None for now
Servicability: Dome lifts off from body and is not bolted on. Right now access is through the holoeye.

Leg structure: 2"x4" Square Aluminum Tubing 0.125" Thick (Local Supplier)
Feet Motors: (2) 24VDC Geared (Gary S)

Motor Specs:

Constant duty

Rated at 4000N (about 900 lb)torque

7" long w/ gearbox

Motor is 4" long x 2.4" wide

Up to 24V operating voltage

24V @ .45A no load

35 rpm @ 24V / 19 rpm @ 12V (no load)

Drive shaft is 3/8" dia. x 1" long w/ 1/8" hole

weight: 2.5 lbs

Radio 6 Channel Airtronics 75.550 Ch 68

Feet Frame: 2"x3" Sq Aluminum Tube & 0.25 Sheet Lexan (Local supplier)
Drive: Chain
Ankles: Scratch built
Shoulders: Scratch built
Shoulder Details: Scratch built
Feet: Modified droidboy vacformed outer shell
Battery boxes: Modified Droidboy vacformed outer shell
Power Cables: Hardware Store for toilet connection
Propulsion System: 5" Dia rubber wheels w/ bearing in hub from Hardware store
Leg assembly: Aluminum bolted or brazed together
Leg to Body System:
1" Dia Aluminum tube is brazed to an aluminum plate
This aluminum plate is bolted to the 2"x4" aluminum sq tube
Each leg has a length of 1" Dia tube that is assembled to the body and screwed together.
The tube is supported inside the body by 2 bearings
Servicability: It would be a major job to change a motor. I would have to rip the feet apart.

Middle Foot: Modified Droidboy vacformed outer shell
Mid foot frame: 1.25x1.25x0.125 Shelving angle
Foot assembly: Welded
Wheel: (1) 3" Dia caster
Servicability: Middle caster is easily accessible

Body Skin: 0.060" Styrene two sheets
Coin Slots: Scratchbuilt
Front Vents: Modified Droidboy
Power Charge Coupling: Modified Droidboy
2-3-2 Mode: n/a
Body Frame: (4) inner sheet metal donuts with expanding foam for rigidity
Body Height: 20"
Body Diameter: 18.5"
Servicability: Through holes in the top and bottom of body. No panels have been opened yet.

RC Unit: Vantech 6 channels 75.55Mhz
(2) MCD Speed controllers
(1) MCD Switch 16 (not used at the moment) - later used for dome roatation

(2) 12VDV 7AH - motors
(4)AA 1.5VDC - 5W Speakers
(4)AA 1.5VDC - RC Receiver
(4)AA 1.5VDC - CD Player
Charging System: none
Serviability: Batteries have to be taken out of body to be charged
Power: (2) toggle switches in back of body to turn on power to
the motors and receiver. This will be moved later on to under
the body where it will be less obvious

CD Player to be wired to MCD switch 16
For now it plays a continuous CD burnt to make an R2 sound every 10 seconds
Speakers: (2) 5W computer speakers 6V that turn on only when a signal is sent

Transport: Legs disassemble from body. Dome disassembles from body
Body does not fit in my trunk but can squeeze into the back seat of my car.

May 2 2001
Here are a few trials and tribulations I had while constructing R2 Some of the information
has been repeated. This was an email to a fellow builder

The RC unit is a Vantec 6 channel ground unit. Note that most multi-channel RC units are for the
air. I had to order this item from my local hobby store since it isn't a common item.
(Cost approx $260CDN)

I went for 6 channels since I wanted to eventually add as much stuff to my R2 as I can. If you want
a bare bones R2 that only moves and rotates his head you only need 3 channels (1 for the dome and 2
for the side feet).

The motors I got from Gary S. They are 12-24VDC and cost $25US each. Right now he does not have any
in stock but is looking to get some more. There were pictures and specifications in the files section.
I don't know if they are still there.

My 5" dia wheels were purchased from a local hardware store. They are for making your own cart, barrel
etc. They have a rubber treaded tire (1in width) with a 1/2" bearing. (approx $7CDN each)

I purchased several gears and chain to attach to my wheel and motor shaft. I did this as opposed to
a direct drive as there was worries that any bumps the wheels would see would be transmitted through
the motor and the bearings in the motor and may eventually wear it out. (cost approx $30CDN total)

I did not design a chain tensioning system into my feet so one chain is relatively tight
and the second one is fairly loose. The tight one I am not worried about since I know The chain will
loosen over time. I am worried that the loose one will come off at some point. My next feet will
have some sort of system to make sure the chain has the correct tension all the time. I am looking
at the system that motorcycles use.

I have a 2x3 aluminum square tube as the mounting point for my motor and wheel. One wheel shaft is
off by a very small amount so that it is not parallel with the motor shaft. This slight offset makes
the wheel and motor slightly drag. This slight difference in the left and right motor means my R2
does not track straight.

I have spring pins that mount the gear to the motor. Unfortunately these are very hard to access
and when one fell out it was a pain to re-install. Also at this point the installation of the
wheel and motor would requires quite a strip down of the feet.

I want to do a redesign of the feet to make things more accessible for maintenance, repairs etc.

I tried to fit the batteries in the battery boxes but I was running out of time and I wasn't comfortable
with the strength of the boxes. Right now my batteries are in the bottom of my body. To put them
there I have to drop them through my frame onto trays. This is not very accessible but it
does keep the weight of the batteries low. I don't have a charging circuit yet so the batteries
have to come out of the body for charging. This isn't too bad as it makes my body lighter when
I transport it.

If you can get these motors they are great since they already have a gearbox, a shaft with a mounting
hole and very high torque. The one problem with them is that I had to do a lot of fiddling to get
the motor to fit in the feet so that there is room for the 12volt batteries in the battery boxes.

Speed controllers
These are MCD speed controllers. I have one for each motor. They were $150CDN each. I think
Ramsey had some that were cheaper. I bought these on the recommendation of Christina & Martin.
I didn't have any other source at the time. I had to switch the wires on the speed controllers
to get them to work with the RC unit. This was relatively simple to do. One problem I have is
the fact that the power to the motor appears to me 100% or nothing. I am not sure if it is the
motor or the programming of the speed controller that is the problem. These are needed as speed
controllers for RC cars would just burn out.

The gears on my motor and wheel were approximately the same diameter. This makes the speed on my
R2 a bit slower than I would have liked at 24VDC. I should have done some quick calculations to
figure out what the speed of R2 would be. I have purchased some smaller gears for the wheel
so that my R2 would travel a bit faster.

Note that my setup with the 5" wheels leaves very little room for anything else in the side feet.
I thought I might be able to put a 2" caster inside the feet for eventual 2-legged mode. After
the problems I had with the stresses at the shoulders I will leave my R2 in 3 legged mode
permanently and not worry about trying to install any casters inside the feet. The 5" wheel takes
up a lot of room and basically has to sits in the middle of the foot. I went for the largest wheels
I could with the initial hope of getting my R2 to run on rough terrain. I have now abandoned those plans.

Hopefully I will add a 2-3-2 legged mode in my next R2. Also by then it is hoped that a few more
club members will have perfected a system to do this process. I have seen Christina's &
Martin's R2 and the amount of time they put into their 2-3-2 legged mechanism is staggering.
Martin is also an electrical genius and the design of the circuits and relays for the 2-3-2
is way beyond what I am used to doing.

To power my circuits I have placed 2 toggle switches on the outside back bottom of my body.
I should relocate them to the skirt underneath so they are more out of site.

I also found that after a bit of running that all the bolts and nuts would loosen and my
joints would go sloppy. No matter how much I tighten them this would happen.

I eventually had to epoxy all the nuts to the bolts. Since my R2 was going to stay in 3-legged
mode I also had to epoxy all the ankle pivot points. The middle foot ankle saw a lot of side forces.
I found the majority of the time R2 was turning or rotating. This meant a lot of side forces on the
middle foot, which translated to quite a bit of force through the ankle. Even though I would tighten
this bolt and nut as tight as I could it would loosen.

One thing I noticed with Christina's and Martin's R2 is that it appears loose at all the joints.
I think this is a function of how much force goes through the joints.

My R2 shakes slightly but I have also cheated and added ILM bars (bars from the feet to the body).
These bars really cut down on the amount of forces at the shoulders and I do not worry as much
when my R2 goes over bumps.

I am surprised at how much has happened during my R2 building process. At the time it was one
problem after another. It was a stressful time but the results of having your R2 move by himself is
a great feeling.

June 4 2001
Last weekend I took my R2 out to a friend's birthday party for his daughter. He had seen my R2 before
and asked if I wouldn't mind bringing it out to show the kids. Of course I had no problem and welcome
any chance to show him off. The party was held in a school gym. Lots of room for my R2 to run around.
The video was taken at the end of the party. The batteries for the leg motors still worked.
Unfortunately the battery for the dome motor was dead so I didn't get and video of the dome rotating.
I had no problems with the kids running up and touching, hugging and even dancing with R2.


If you want to build your own R2 go here --

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for an R7 go here --

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