Nightmare Repairs At Competition

[Karibou]

West Michigan District 2011, we destroyed our drivetrain.

One of the bolts in the drivetrain came loose during a match, and the wheels on that side stopped turning. The drivers kept driving on it because they had no way of knowing if it was an electrical, code, or mechanical problem. I didn't see the match because I was cleaning the pit, but when they brought the robot back after the match, I nearly cried.



Unfortunately, this is the best picture I have. You can't see the full extent of the damage, which is several chunks/teeth missing. I think there was some damage to the chain and maybe the axle it was on, but I don't remember - I wish that in our state of panic, we would have thought to get a picture. It was bad. That sprocket was on the center axle and was welded to a hub with another sprocket to form a sandwich. We sent the sandwich and a new sprocket with a mentor allllll the way to the machine shop on the other side of campus to be welded and worked on cleaning all the metal shavings out of the robot and fixing other problems (it turns out that 24V valves in your pneumatics won't work too well) while waiting for it to come back.

Mentor comes back with the destroyed sprocket (IIRC it wasn't bent that badly before sending it there, that was just a result of getting it off of the sandwich) and the new sandwich...which was still not usable. Apparently the welding machine jumped and the result was a tooth that was completely missing and some other tooth deformation. Sent it back to see if anything else could be done, and asked frantically through the pits to see if anyone else had a spare sprocket that we could have. We found one, and decided to drill some holes in our only spare hub and bolt everything together. Ten minutes of ratcheting and two sore wrists later, we had a sandwich that was usable.

It was by no means the best fix, but we had already missed several matches and our next one was in a few minutes. We made it out to the field literally just in time to play for our last match of the day.

-----
Not a nightmare repair at the competition, but definitely a pain in the everything:
http://www.chiefdelphi.com/media/photos/35270
See that bent corner? Having to attempt to straighten it after every match that we moved in was the bane of my existence that year. That robot was all about poor design choices, and the frame was one of them.