I have a question you people who have designed lots of robot
what should be the thichness of the aluminum frame?
A little more information would probably be necessary for you to receive any kind of specific advice. What do intend to make the frame from: flat pieces, tubes, channels, L’s? A description of the robot, intended functions, and the amount of weight it will need to be able to support would also be helpful. My own experiences is that the limiting factor is the capacity of the servos to handle the load and not the strength of the frame.
The Phoenix components seem plenty strong but I’m not surry what the carrying capacity is. Those components are made from T6 aluminum:
Tibia and Femur parts 0.125" (3.175 mm)
Chassis parts 0.063" (1.6 mm)
the pictuıre of my SW robot model
http://img208.imageshack.us/img208/9590/10722791hb5cf1.jpg
http://img220.imageshack.us/img220/5729/biped5lg3.jpg
I am looking for hs-475 servos ill it be ok . After some search 2.5 mm tickness aluminum sheet was used on some robots. with my calculation the robot will weight about 2.5 kg~3kg
ANd I would like to ask how to put some bearing to the other side of the servo I bought some flanged f693zz 3x4x8 bearing how to couple them to the aluminum sheet.
help would be apreciated
The 475’s won’t be enough for the job. You will need to go with 5645 minimum. For the rest I don’t know.
If not higher than that… 5645s might be enough for just the walker itself, but doesnt leave much room for expansion. To be honest I wouldnt ever build a 6dof+ walker with anything less than 5990TGs, as expensive as that is. (and hence why I dont have one)
You should consider that the top-most two servos attached to the plate are going to get chewed up badly as you are supporting each entire leg from a single servo output shaft. Some research into how the Lynxmotion scout bipeds make that joint work may save you a lot of heartache and $$$ down the road.
actually I think the scout kits can be bought with either 5475 or 5645 servos, but I too really doubt it will work with regualr analog 475s. Even if it can lift itself it would probably walk like parkie scout did. 
Yes we do sell the Scout with 5475 servos, but that’s a bare minimum and you will have to tether the power to the bot. 5645’s is enough to walk and do lots of moves, but the 5990’s would be an improvement.
Thank your very much guies for your pecious advice,
Seems that my robot will cost me a fortune to realize.
Th eprincipal cost are the sevos, unfortunately there are not not low cost servos with reliable power out there.
I wonder myself about the servos at the top which supports all the legs.
I think I have to wok a little more about it.
more advice will be well appreciated