Servo - December 2013

SERVO 12.2013 33

okay robot can beat a great robot with a bad driver, so we needed some practice. We began by simply drawing a big square with sidewalk chalk on the driveway. The last bot remaining in the square was the winner. We made a big square on the order of 12' x 12', so their random stick mashing style didn't result in two bots immediately driving out of the square.

The problem was they still had issues driving and they kept dropping the remotes. I watched their hands closely and noticed their little fingers were too short to hold the remote and move the joysticks. I pulled out some chairs and voilá, the driving improved immediately.

The boys started getting even better with each match. The first couple matches only lasted a few seconds before someone drove out (without ever touching each other).

After a few days, they started being able to run into each other occasionally before immediately driving out of the square. Then, the bad stuff started happening. I was letting one of Cayden's friends try driving Angry bot when suddenly one of the wheels fell off. I assumed the screws just vibrated loose.

On further inspection, it turns out the gear case itself had failed allowing the face mounting bolts to fall out. I realized my mistake. I had never put an outboard support on the BaneBot gearmotor.

I knew that was a big no-no, so I took Cayden's robot back in and began building an outboard support for it. It took me a couple days, but we got it back up and running.

The new setup was much stronger. I also used the shaft support as a means to keep the robot from tipping, so I was able to remove the bent aluminum plate. The boys were back in business fighting in the driveway.

At this time. I started to notice that Cayden was getting some pretty good wear on his wheels, so I decided it was time to break out the plywood and build a … wait for it … arena. It's getting serious now. By arena, I mean a 4' x 4' plywood floor with some 1 x 4s nailed to the edge to provide some walls and an opening on one side. We broke out the house paints and had some fun decorating up the arena with shapes and pictures.

After a few days of practicing in the new arena, we decided these robots needed some paint too, so we went out in the garage and picked out our favorite colors. Cayden went with red and Ethan went with green.

Both boys wanted to try to paint them, and I couldn't come up with a reason why not to, so we went for it.

With my help to push the button down, they actually did pretty well.

After a couple coats of color, the boys explained that they wanted their robots to look like things. Cayden wanted his robot to look like an Angry Bird and Ethan said he wanted his to look like a scary monster.

Ethan explained that he wanted a scary robot, so the other robots would just run away and fall in the pit. (That's a pretty good strategy for a wedge bot!) I certainly couldn't argue with his logic. I broke out the pencil and permanent marker, and after an hour or two (like eight) I finally had an ogre and an angry bird. Once they had paint, the boys decided to name their robots Scary for the scary monster and Angry Bot for the Angry Bird.

I applied a couple coats of clear-coat to help protect their

"masterpieces," then we got the bots back together again for a couple more days of fighting. We had a week to practice, so all should be well. We started honing our skills and after a few fights, I noticed Cayden's robot started to pull to the left. I picked up the bot and one drive motor face was loose. I tightened the screws, but one didn't feel like it really tightened. I decided to open the case and check it out, and my worst fear was realized. The gear case had shattered again, and I didn't have any more replacements. I decided to order a pair of the 20:1 Finger Tech Spark motors from Robot Marketplace. I went with the gold series, and I was not disappointed. The motors arrived on Wednesday and on Friday we had to leave for Florida. I took out the old PVC mounts and made a one piece mount for both Spark motors. This saved me two steel PVC clamps, so I had some more weight to spare. I got everything wired up and reweighed the bot. With the weight savings, I was able to add rear armor. Boy, did that turn out to be handy. Cayden and Ethan had one night to practice driving for about 20 minutes and then it was bed-time. We were ready to head to the Orlando Mini-Maker Faire.