Over the past few weeks, I've been working with my machinist friend on some ideas on installing the linear actuators into R2's frame. Originally the shoulders were designed to work with an actuator with a 3 inch stroke but the shoulders actually have a bit more movement than that...about 3.4 inches. The way the shoulders work, the four bolts rotate thru the grooves. They all for the shoulders to rotate back, when in 3-leg position and upright, in 2 leg. They also also for a few degrees to tip forward, allowing us builders to articulate and create "body rocking/body movement".
I decided to go with 4 inch stroke actuators equipped with potentiometers. In the closed position, they will put R2-D2 in it's 3-leg position. Since the stroke is larger that the movement allowed (3.4 inches), I will use the data from the potentiometers to stop them before they exceed the travel allowed.
Attaching the actuators to the shoulder levers went fine, although we decided to use a 1/4-20 sized bolt.
Since the potentiometer equipped actuators are longer than the original design, we had to come up with a way to fit them into the frame. Before we could snub them into the lever, we had to do something about the bottom attach point. We want the actuator to be straight for its vertical lifting and retracting.
To overcome this, we did two things: We made mountings to bolt under the frame ring and small cut outs for the actuators to mount straight.
With that side done, it was on to the next....and now, the actuators are both installed!