Are Custom Parts Worth the Effort?

Recently, my team has begun to construct the scoring robot we think will work for competition. In order to fit everything into our 18″ x 18″ x 18″ frame, we decided to make our own robot frame out of 16 or 22 gauge steel. Many of our new members were puzzled by this, and the new team had not considered it until we suggested that they do so. This made me consider all the advantages that custom parts bring to the table. Tetrix parts are useful and available, and that’s why it’s nice to use them early in the season to create simple parts of the robot and to decide how you want the robot to function. But once you’ve figured that part out, Tetrix parts begin to fall short. For one thing, Tetrix parts are almost exclusively aluminum, which means soft & bendable. This is a nice feature if you intend to drill through it, but if you want moving parts that don’t mesh together, and screws that don’t strip with a little too much tightening, aluminum is not your metal. the other thing that Tetrix parts always have, are pre-made holes that are meant to line up in certain ways. This means that if you wish to use them in a slightly different way than intended, holes may not line up perfectly and drilling may be necessary. This would be ok if the purpose of the object is neither weight nor pressure intensive, but say that it’s a vital part of the scoring mechanics; the lack of structural support may cause the pieces to break overtime. Lastly, Tetrix parts can usually fulfill the same task as custom parts can, if you give them the space and proper construction. The unfortunate thing is that we are limited to an 18″ x 18″ x 18″ build area, and proper construction usually takes time; time we may not have.
This is where custom parts excel. Custom parts are not usually that much more expensive when compared to Tetrix pieces (this is not a credit to custom parts, but a detriment to Tetrix). We find this to be especially true because we can get sheet metal shaped into parts for a bare minimum of expense at a local engineering company. Most parts that are made custom are made out of Steel, Lexan polycarbonate, or ABS plastic (depending on their function). Steel solves all the problems one would find with Tetrix parts but can be heavy if it is too thick or if the object is larger. Lexan polycarbonate is a Plexiglas-like material that is almost impossible to break and easier to shape than steel (can be shaped with a heat gun). ABS plastic is very similar to Plexiglas, but given that it is traditionally used in 3D printers, the small size of parts makes them more susceptible to breaking. Don’t let this deter you though, ABS is a strong plastic and 3D printed parts are truly the prodigal apex of custom parts.
Right now, we’re designing a steel box to house the motor controls, battery, and wires of the robot, as well as provide a platform for our arm design and to protect the wheels from other robots, and field obstacles. We think that this can all be done with one continuous piece of steel, of whichever gauge we decide on. On top of this box, the extendable arm will be made of 1″ square aluminum pipes and drawer slides. This should be better than using pre-made Tetrix pieces, because the pipes will be more structurally sound (fewer unneeded holes). I feel that as time progresses, we will continue to use more custom parts and a wider variety of build materials. I’m particularly excited to design parts from our pending 3D printer, which should make smaller parts easier to make. I hope to provide the first pictures of our base robot soon, with our custom materials in place.

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