ME360 Project #3: Model Scribe Machine

The goal of this project was to create a machine that can draw simple shapes and objects about a 2-dimensional plane. This is done by creating 3 separate components, each made by a different team. 2 of these components serve as supports for the third component, which includes a unique 3D-printed attachment for the pen to slide through perpendicular to the paper it will draw on.

Pictured below is the component that my group and I created:

Figure 1: Model of our Scribe Machine Component

Our component is a support component for the final machine that utilizes 1.5 degrees of freedom, as it can move back and forth parallel to the cardboard base, and the coupler transmits rotational power between the shaft of the stepper motor in the back and the threaded rod. The rod is held in a straight line by the 2 flange bearings and the brass nut, allowing for smoother translation across the base. The brass nut rotates as the rod is rotating, and this allows the central cardboard piece attached to the nut to move freely. It was cut out by an extra length so that the end component that we would add the pen to could be placed on top of it with adequate support from the bottom.

The final scribe machine is shown below, in this video that captures all 3 sub-components in action:

Video 1: Showcasing of the final Model Scribe Machine. Here, we created a square and then added diagonals to it to demonstrate how it can move in 2.5 degrees of freedom.

Our component is the one picture on the bottom. As described above, it supports the component with the pen attached to the stepper motor. The x-axis and y-axis translation allows the squares and diagonals to be successfully drawn. To accomplish this electronically, we utilized Repetir-Host G-code, which is a control programming language, to pre-program the motors to rotate until a set location is reached.

The range for which the top component travels was set by the average constraints based on the distance between our support component's vertical walls and the other support component's walls. Additionally, for the stepper motors to achieve smooth motion at the low pre-set speeds, we utilized micro-stepping which does not require any mechanical changes, and thus making the building process easier.

Some design components I would have changed for the overall machine would be to create a flatter base from the start. Additionally, for our own component, I would have created a wall that matched the height of the max support wall of the other team's support component. Originally, our heights didn't match and for this reason, when we lowered the pen to the tip of the paper for drawing, it would either go too deep, or just barely grace the paper and not properly drawing a side of the square. Creating a flat base for the paper would help fix this as well, eliminating further imbalance for when we would try to complete the drawing.