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Mounting the tracks

The most difficult part of the base assembly is getting the tracks onto the bogie wheels. First, you must assemble the tracks into continuous loops. The tracks are composed of a bunch of small plastic tread units that are connected to each other with small metal pins. If you look at your tracks, one end will have a pin, and the other will not. You have to remove the pin by pulling or pushing it out using a thumbtack (which was helpfully provided in the kit). You want to push the pin away from the side with the small cylinders – it needs to come out the other side. You can see this in the following image. Pull the pin out far enough to engage the two ends of the track, and carefully push it back in to connect the track. I did not need the extra track sections that were provided. Now we have a loop of track. If you put the frontmost bogie wheel on the drive section, remove it now. Loop the track around the bogie wheels and over the drive wheel. You will have to adjust the drive wheel in or out to engage the sprockets with the tracks. Now you have to lever the front drive bogie wheel into place by angling the long screw into its hole and tightening the nut until it all drops into place. This took a fair amount of effort and about an hour of careful wiggling to get it all to line up. You must keep at it until you can move the tracks easily around the bogie wheels and the drive wheel. If one of the bogie wheels is stuck, loosen up the lock nut just a tiny bit to allow it to turn without binding. There is no track tension adjustment on this kit, which can be a problem. You can make the front bogie wheel a slot rather than a hole to get some tension adjustment. I did not have to do this on my version of the robot kit:

Now we can assemble the other large base plate on the bottom two holes in the track plates and our drive base is complete. The second base plate goes upside down relative to the first plate – the bent outer section goes up. I staggered the two plates by rotating the bottom plate 180 degrees, but they can also go exactly parallel if you want. I liked the staggered arrangement for later placement of sensors.

You will need to solder wires onto the drive motors before installing the robot arm. Some very nice spaghetti wire was included in the kit for this purpose.

Spaghetti wire has a high strand count, and is very flexible, making it ideal for use with motors or anywhere where you are expecting a lot of movement or vibration. We call it spaghetti wire because it is limp, like cooked spaghetti, not stiff like most wire.

Now I have some good news and some bad news: We are done with the base (good news!) but we still have to do the arm, and it is much more difficult to assemble (bad news!).

An important note regarding Servo installation: you need to install the servos in the arm at the middle of their travel. Each servo can turn its gears through 170 degrees of angle. You need to assemble the arm with the servos in the middle. I ran the servos all the way to the left by turning the gear by hand, and then all the way to the right, and then picked a point half-way before putting them into the arm. I tried to visualize each arm joint in the middle of its travel, and assemble the arm that way.