When you design a robot, it is important to think of not only the features of the robot, but also the materials that make up those features. Understanding the materials and their capabilities and limits make it easier to choose which one(s) will be best for your robot.
Tetrix is the standard building platform for FTC robots. Tetrix utilizes c-channels as the main building block. C-channels are connected to each other utilizing screws and nuts. There are also other pieces such as various brackets and bars. Tetrix is a great way for new and old teams to build the framework of their robot.
Matrix is also another standard building platform for FTC robots. Matrix utilizes c shaped beams and plates to form a frame. However, Matrix is not as common as Tetrix; the hole pattern is more difficult to utilize. Very few robots are made using Matrix.
Many teams choose to build custom robots over using base kits such as Tetrix or Matrix. This allows them to not be limited by the restraints of building by C-Channels or Beams. To make a custom robot, a team needs to design the robot out using CAD, then having a company machine the parts for them. While teams are able to design their robot with freedom, it can be quite costly to have a company machine the parts for them. Furthermore, if a team wants to make design changes, it can be difficult to make changes to a fully designed robot.
i^2 robotics’ fantastic custom robot during the 2014-2015 Cascade Effect! season.
80-20 uses aluminum “t-slotted” extrusions and various brackets to connect with each other. Instead of pre-drilled holes like Tetrix and Matrix, 80-20 allows teams to pick where they want to put an axle, wheel, etc. 80-20 is also useful for linear slides.
A robot made by 5037 got robot? made almost entirely out of 80-20.
REV Robotics is a newly developed system that FTC teams can use. REV utilizes extrusions(similar to 80-20) and allows you to slide parts to where you want them. It is also designed to be more space efficient; their extrusions are 1/4th the size of the standard Tetrix C-Channels. They are still developing their products, so check them out on their website: http://www.revrobotics.com
Actobotics is a build system that is similar in design to Tetrix that is utilized by many top teams. The main building blocks are also C-Channels; however, the C-Channels are different in that they have many more holes and are larger. The larger amount of holes allows for more securing points. Furthermore, Actobotics has many more options for various brackets and mounts than Tetrix does, allowing for greater building capacity. They also have different sized sprockets and gears that can be utilized. Keep in mind that while the appearance is similar to Tetrix, the holes do not line up great so it is difficult to match the two together.
Eagles Robotics Xperience, one of the many successful teams using Actobotics.
Prototyping is a key component of having a successful design. To test out various designs, often it is important to use materials that are not costly and easy to make.
Foam core is a very useful prototyping material. It is easy to cut with an x-acto knife and easily put together utilizing tape or hot glue. It is also very cheap and accessible. Foam Core can be used for a lot of things, such as guides, hoppers for item storage, walls, etc.
Cardboard, like foam core, is also great prototyping material. It is found almost everywhere and easy to manipulate, cut, and bend. Depending on the layers of corrugation, it can be slightly flimsy, which is where foam core would be more useful.
For custom parts that cannot be made out of your standard building kit, designing with the following materials can be very helpful.
Lexan is a see-through, plastic like material. It has great properties that allow it to be a fantastic building material. It is easy to manipulate it by drilling, cutting, and can be bent by utilizing a heat gun. It is difficult for lexan to break but vulnerable to scratching.
Acrylic is similar in appearance to Lexan. Acrylic is cheaper than lexan, and both of them are stronger than glass; acrylic is about 4 to 8 times stronger, while lexan is about 200 times stronger. However, acrylic is vulnerable to cracking whenever you try and manipulate it, such as breaking whenever you try to drill a hole or use a center punch on it. If you chose to use acrylic, be very careful when cutting and drilling holes.
PETG is another plastic option that can be used. PETG, in comparison with other plastics, is about 70% as durable and strong as lexan, which is much stronger than acrylic. However, it is cheaper than lexan, as well as lighter. PETG could be useful for making a hopper on a linear slide that you want as little weight as possible on.
Sheet metal can also be very useful for making custom parts. Unlike plastics, sheet metal is not see through; however, it does have other advantages. Although it is very thin, it is also very strong and durable. It’s also malleable, so it can be easily bent into a shape that you want. It can be cut utilizing either a plasma cutter or using metal shears. It is harder to manipulate than plastics.
3-D printing is also a very useful tool for making custom materials. 3-D printing utilizes filaments that stack to form a shape. There are two commonly used filaments, which are PLA and ABS. PLA creates parts that are shinier, more environmentally friendly, and less susceptible to warping. ABS creates parts that are strong and flexible. 3-D printing is useful for creating parts that would accomplish tasks that other materials cannot; however, be careful for using it as major structural parts, as it is easy to break under stress.