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 fiberopticsproducts.com 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.
Other:
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
Batteries:
(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
Sound:
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)
Problems
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.
Batteries
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.
Motors
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.
Gears
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
If you want to build your own R2 go here --http://groups.yahoo.com/group/r2builders
or here --http://movies.groups.yahoo.com/group/astromechs
for an R7 go here --http://movies.groups.yahoo.com/group/r7droidbuilders
Email me ask@interlog.com