Originally Posted by KleinKid (Post 1015340)

Our arm design has the shoulder joint at a fixed location offset towards the back of the robot. In its starting configuration it should be about 55" long and after extension it should be 64" long. I am looking into using pneumatics for the extension but many members on my team want to use a threaded rod hooked up to one of the banebot motors.


Our material for our arm is 1" aluminum tubing with 1/8" thickness which is a little heavy duty for what were using it for but it's whats left over after we build the frame to support the arm.


Instead of mounting the large sprocket to an axle could we mount our two large sprockets directly on the arm by drilling holes through the sprockets and bolting it directly onto the aluminum tubing?

Originally Posted by eedoga (Post 1012166)

Things are going so smoothly I'm starting to get scared. We drove our robot today. It took a little figuring out, and some polarity switching at the motors, but we drove our robot today...And not even as a last minute thing, we drove it before we broke for lunch. Not only did we drive it then, but we got to drive it a bit after. Our driver said "I am amazed that it drives so smoothly." We've never had that happen before. We also finished welding the tower, and the arm, and got up to the first arm segment roughed in. We even got to clean the classroom up. :-)

Ok...So some pictures.

In this pick the second arm segment is just stuck in. We still haven't mounted the linear bearings that will allow it to slide back and forth. We also haven't plummed or wired the piston, or mounted the cable organizers that will allow the arm to move back and forth without ripping the wires out.


This is a much better indicator of our actual progress. We may paint the base purple and the arm gold (our school colors) but I sort of doubt that that will happen before the competition. We may do it after the competition to help raise money and awareness for next year.


This shows a close up of how the arm rotation is going to work. The window washer motor is mounted below in back. The sprocket has two holes drilled and tapped to 1/4 * 20. We used the shaft from the gearbox that came with this years kit linked to the large sprocket on the other side. Some 1/2 inch inside diameter bearings complete it all so that power can be transferred from the 60 toothed gear to the arm. The gear ratio between the windshield wiper motor and the large gear is 1:2, so I'm hoping the motor will be able to turn the arm, while retaining a reasonable turning rate. If that fails, plan B is to add a second windshield wiper motor on the other side and tie the two together.


Here is a close up of our electronics bay. We are still trying to kill the spaghetti monster lurking in there. you can also see the Pneumatics which are coming along nicely. We are using two smaller tanks, and the bigger tank that came with this years kit of parts. We figure filling the 20 inch * 2 piston we are using to deploy the minibot will use up most of the stored air even though its on the low power side of the system.


Here you can see the relief valve and power switch which are both accessible without reaching in the way of any moving parts, or anything sharp. We are a bit concerned about the gauge that is mounted on the top of the frame rail might get hit by something if another team carelessly hits it, but hopefully not.

We weighed the base, and it was only 89 pounds with everything except the tower, arm, and battery. (Battery isn't included in the weight limit). The tower weighed in at about 5, and the arm was only about 8 total, so we are actually looking at coming in right around the perfect weight. (Again, something that has never happened to us before.)

We still have a lot of work to do, our minibot is still a figment of our imagination. We also have to finish up the arm extension, and then do a final tear down, prep, and rebuild where we use locktite on all the nuts, and make sure everything is where it should be. All in all, a great day for 2980!