# Week 11: Machine Week, or In Which I Try to be Useful <a href="../index.html">Back to Home</a> After relatively brief discussion (< 1hr) my group decided to make a 3-axis milling machine. I joined the CAD/Fabrication team because all the software talk was decidely scary and I didn't want to have to be part of end effector team, which would have to do everything at the end. I was a bit worried that I wouldn't be able to contribute anything, since there was nothing that I could do that someone else in my section couldn't do better. But there was a lot of work to be done, so an amateur could still be of ample assistance - and I learned a good deal too. In summary, the machine works thus: * Control motor spin through software * Motors turn a secured component that has belt treads, against which the belt is held taught by two pulleys; the belt is secured on both ends of the rail by a set of components through which it is threaded and by which means the belt can be tightened. * Motor is mounted on carriage, so as motor turns, carriage moves along belt * Each axis is essentially identical, save for the mounting of the z-axis on the x-axis, which moves along two y-axes. ## Glossary of Components * Gantry/carriage: carries the motor and rolls along the rail * Rail: provides path for carriage to roll along * Stepper motors: turns in very precise increments to move something it's attached to (by tension belt) precisely * Spindle motors: spins the milling bit, connected via belt to a gear that turns the collet that hold the bit * Bearing: connected via a special (?) screw to carriage, allows for smooth rolling of one surface against another; also useful for tensioning belts ## New Tools/Concepts * Tapping * Countersinking * Why high voltage input to motors? Given the same current, higher voltage = higher power = more precise control ## Other things learned * Milling and 3D printing are not perfect; post-processing with bandsaw, utility knife, and filer are often necessary to get tolerances right, especially for press-fit pieces * It's really annoying to get rafts off pieces printed by the Sindoh, and 3D-printed pieces are quite brittle