Horizontal Thwack Bots - Novice
- Adam Wrigley
Last updated - June 2006

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Build Responsibly.

Horizontal thwackbots are a great choice for the new builder. They offer a simple design, while still having a weapon. The general idea is that a robot can spin without having a separate "spin motor." Simply reverse the directions of the drive motors, and the robot will spin in place. There are a few main types of horizontal thwack robots, the most popular being to simply mount a hammer onto the back of the robot:

This design is also generally coupled with some form of wedge on the front. The idea is to drive around with the hammer behind, and then whip it around into the opponent as they come towards you, hitting the opponent in the side. This works well coupled with good driving, and is easy to build. However, it can also cause the robot to be off balance when spinning, slowing down the top speed of the hammer. Though, for this to become a factor, you'd have to be spinning in place for more than just 180 degrees. While continually spinning in place can get your robot up to a higher speed, it makes you need to wait for the opponent to hit you, since you cannot move while spinning. If you think you'll be using this tactic, and are worried about being off balance, the easiest way to fix this, is to simply mount a hammer on the other side of the robot:

This will give you balance when spinning, but at the cost of effectiveness when NOT spinning. Generally, thwackbots will have some form of wedge on the front of their robot, to use in pushing around the opponent. If you mount a hammer on the front, you obviously can't mount a wedge there too. However, if you think you will be spinning in place a lot, maybe you won't need the wedge.

The most optimum way to balance the bot is to move all of your internal components to the front of the chassis, and lighten your hammer at the rear. This can be trickier than just mounting a hammer on the front, but it gives you the best of both worlds as it allows you to spin fast in place, and have a wedge if you want to be aggressive:

Another sometimes used design is not one generally suited for beginners as it entails complicated mechanical or electrical design to get it to work correctly. Some builders have been able to create robots with teeth mounted onto the corners of a chassis, similar to this:

Robots of this nature are always spinning in a circle, and are controlled through advanced electronics or mechanics that can slightly alter the speed or angle of the drive wheels, causing them to translate across the floor, while spinning. These are extremely hard to build, and have not had the best record in combat.

When designing a robot of the first three types, the most important factor is the width of your drive train. The closer your wheels are together, the faster you will spin, but at the cost of maneuverability (you'll be over steering a lot) Also, make sure that your robot only has 2 wheels. Robots with 4 wheels will have massive amounts of friction when turning, greatly decreasing their effectiveness when whipping around a tail. Since thwack bots are two wheel drive, it is also important that your robot have skid plates where the chassis touches the ground. UHMW or Delrin are good materials for this purpose.