Could i use a pan and tilt for a robotic arm? Does the tilter reach 90 degrees so the arm can rest facing down? The arm might be a bit more than only 2 pounds, could i use a hitech 422 for more weight/torque?
Ok, i studied it a bit more, i could use a pan and tilter, and just mount the tilt horn accordingly. Or i could go with another option, by making my own pan and tilter arm, using "C"brackets, plus adding one more shoulder motor for better biological DOF. Also I think I would add the pan,first,then the tilter motor, then the other.
I added up a total of 6 servo motors for a complete robot/Android arm (excluding hand/finger grip)
3 in shoulder(forward/side/rotate)
1/2 elbow (bend/rotate)
1 wrist
You seem to have answered your own question: almost all robotic arm shoulder joints (as well as hip joints in walking robots) are essentially pan and tilt systems (2 D.O.F.). Lynxmotion (and other companies) realized this a while ago and made interchangeable, modular components. Their pan and tilt system uses the same components as more of their walking robots and robotic arms.
Compare for yourself:
Remember that a servo supporting a load only by the horn supports a lot less than one that is connected in two places (image at far right). Use the RobotShop Robotic Arm Torque Calculator to find how much torque you will need in each of your joints. If you’re unsure of the equations involved, take a look at the tutorial.