On Saturday I made a lot more progress on the overall robot. Design work is largely done, at this point I'm working on finishing the prototype robot. I see that our website managers have moved the lab diary out of public view until teams get farther along, so I'll go ahead and say more about where we are. I've figured out the cylinders we need for the wrist and grip actions, Sam and I made nearly final parts for both the wrist and grip actions, and we're to the point of needing Dale to order more cylinders from Bimba. On friday we recieved the last order of cylinders from Bimba, a whopping 26 identical cylinders, each with a 3/4 inch bore and 10 inch stroke.

Because FIRST requires that we use cylinders from a specific list they give us, we have to butt two 10 inch cylinders together for a 20 inch stroke. I originally thought we would mount these with the "tail" ends together and the piston rods sticking out, but today I've been thinking about it more, and I think it will be stronger to mount them with the piston rods together and the tails out. If we connect them tail to tail, the cylinder bodies will move relative to both the lift platform and the robot, whereas if we mount them with the piston rods together, the top cylinder body does not move relative to the platform, and the bottom cylinder body does not move relative to the robot.

I understand that what I'm saying about mounting the cylinders probably doesn't make very much sense so I'll attempt to explain. The best analogy I've come up with so far is this; Say we have 8 halves of rubber bouncy balls (4 bouncy balls cut in half). First we put the bouncy ball halves back together in a normal fashion, forming a sphere. If we put our four re-constructed bouncy balls on a table, and place a hard-cover book on top, the book will be easy to move, because the balls will roll around underneath. This is like mounting the cylinders tail to tail, the wide flat joint between the halves of the ball is quite stiff (like the tail to tail joint on the cylinders), while the contact points on the table and book are not (like the attachment at the rod end. Now say we take our halves back apart and put them together with the flat sides out, and the round sides together. This is hard to set up, and might require taping 4 halves to the book so that they don't roll off the ones on the table before you put the book on. Once this is all set up, each pair will look somewhat like an hourglass, with the wide flat areas in contact with the table and the book, and a small area where the half-spheres contact each-other. This setup will be significantly stiffer, the book will not move easily. This is like mounting the piston rods together, and the tails apart, while the joint between the piston rod ends is relatively weak in torsion or torque, it is fairly strong in sheer strength at the joint. The cylinder bodies can be much more stiffly mounted to the robot frame or the lift platform than the rod ends, like the large flat sides of the half-spheres in contact with the book and table rather than the spherical sides. — If this still doesn't make sense, you're on our team, and you want to understand it better, ask me.