R2 Generic Frame?
Nov 21 2003
As of the above date there is no standard for the frame in R2-D2. Currently each person builds their frame according to the tools they have and the skills they are comfortable with.
There is no generic frame offered by the R2 Builders club. Can there be a generic frame offered? By frame I mean you bolt it together and then you can quickly add skins and legs and dome etc. I personally do not think so since each builder will have different motors, 232 systems, shoulder systems, batteries etc. A mounting for a motor will be good for one person but will be different if they had a different motor.
A lot of people can not use a metal frame since they do not have the tools or sources to make one.
However what if some minor components were supplied? This can give them a basis for a strong frame to start with. These would be just cut pieces. No holes drilled or tapped. The builder can orient and move the pieces according to their needs.
For assembly you will need a drill and drill bits which most people have. Using nuts and bolts you can quickly join the parts. If you are keen you can also drill and tap mounting points. Taps are not that expensive. You can standardize on one tap size and just buy that size instead of a large set of taps and dies.
The first pieces are a 2x2 aluminum tube. They are spaced apart to try and put them as close to the shoulder as possible. Any loads from the side legs will go straight to the frame. Any load from the middle leg will go down the frame.
Next we have 2 1x2 aluminum tubes that join the two vertical ones. The two cross pieces makes the frame rigid. They are located at the back to allow room for a middle foot and maybe a J-bar
And finally a 1/2 inch plate of aluminum. This plate goes all the way to the bottom of the skirt. If this is not desired the plates can be mounted higher up.
The 1/2 inch aluminum plates allow you to place two 12VDC 7.2AH gel cell batteries in the body right beside the battery boxes.
This gives you a rigid box that you can then mount stuff to. If you have bearings you can mount these to the frame for the leg connections. If you have wood rings for the body frame these can be mounted to the frame with angles, then the body shell can be mounted to the wooden rings.
So why a 2x2 at the top? This will allow a lot of stuff to be bolted to the main vertical frame. It would be harder to mount stuff to the 1x2 horizontal members. You can mount bearing blocks to the 2x2 for the side leg axel, motor brackets, guides for the middle foot, frame rings etc. If the material was steel you can directly drill and tap the metal so you will not need the nuts if you use bolts.
Why a 1x2 horizontal members? I think a 2x2 is overkill and not much is mounted to the 1x2
Why the 1/2 inch plate on the bottom? There is little room at the bottom with the 3rd leg and skirt. If the 2x2 was to extend to the bottom then there would not be room for the 12VDC 7.2AH gel cells in the sides.
Why would I want the batteries there? You don't have to put batteries there but things can get pretty tight once you start adding stuff and I like the location because you can create an access panel in the side to easily remove and replace the battery if you have an external charger.
This also means I can have batteries in the battery box for the motors and in the body for internal stuff. Receiver, dome motor, sound system, solenoids, 232 motor etc.
Notes:
Aluminum is lighter and shipping would be cheaper but it may be more expensive to buy the raw materials. Steel is cheaper but a lot heavier so shipping costs will be a lot more.
The 1/2 inch plate would be the most expensive part of the frame. I decided to go with it to allow space for the batteries. If the 2x2 was to go all the way to the bottom of the body it would be cheaper but you do lose the ability to place batteries as described above. I think this is an important point. Others may not.
The 1/2 in plate goes to the very bottom of the skirt so if you have the body resting on the floor all the weight goes straight to the frame.
Since holes are not provided and the builder does all the drilling then there is a lot of flexibility for each builder.
Is it possible I will design a full frame? Yes it is likely that I will work with other members to provide a full frame with the 232 designed in but it would take a long time to design this system. The next step is to build some test frames to test all the theories. I will not feel good offering something substandard to other builders.
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