Team 2980's Open Source FIRST BOT

[eedoga]

@ Brandon_L
Yeah..the top sprocket is 60 toothed...not sure about the bottom, but 24 sounds right.

@ Klienkid

connecting the sprocket directly to the side of the arm would have created a few different conflicts for us. First off it would make it so that the arm would interact unfavorably with the motor. Second, the chain would rub on the side of the arm, or the inside of the tower making it hard to line everything up. Remember...everything really wants to move so that the chain will bind up or come off with this setup...to be honest I'm a bit worried about the whole thing not working out...guess that is why we have the next few weeks for testing, breaking, and fixing.

You could use a pneumatic piston to extend the arm, but that has its limitations. First off, we are going to have 24 inches of extension. To get that with a piston would add a lot of weight to your arm. The threaded rod idea is cool, but the motor would have to be spinning really fast, or the threads would have to be really shallow in order to be able to extend and retract your arm at a reasonable rate. Now that I think about it, there is that weird threaded rod in the KOP that would work nicely for that...so maybe that is the way to go.

We are most likely going to use another DENSO motor. The idea is you have a round spindle, with 2 ropes or wires wrapped around it. One wire extends down over the end of the arm and then to the back where it attaches to the back of the extension slide, the other goes over the back of the arm and attaches to the front of the extension. Turning the drum winds up one of the strings while un-winding the other so that the slide is pulled forward down the arm. Turning the drum the other direction winds the back string while unwinding the front one, pulling the slide back up the arm. By shortening the arm 24 inches you are lessoning the torque required to rotate the arm around. We will hopefully have a video demonstrating this by late saturday with a tutorial on how to do it on sunday. I may be able to get drawings up by the end of the day tomorrow.

Edoga