This Motori CNC plotter is capable of delivering great results by implementing a 300mW laser and incorporating speed and precision. The power of the laser is enough to cut into thin films according to the maker. In high density foam and pyro-engraved wood, it can make a hole 10-12mm deep as shown in the images below.

Motori is a part of a traditional flatbed plotter that uses a 2D coordinate table where a pen-holding carriage is delivered to any position within the plotting area. The pen can be moved up and down due to the mechanism of the carriage. A trace on paper remains when the pen is down and carriage is moving. It can be transformed as a cutting plotter to cut out signs and labels by putting a knife on the pen holder. A frame that supports rails or guide rods that constitute the X-axis is available in the gantry. The Y-axis is the other pair of rails that is carried by the pillow blocks that travel back and forth on these rods as shown below. The carriage with a pen travels along the Y-axis.

The 3-axis CNC machines can be compared to XY plotters since they share a lot in common. But since CNC machine is designed to be rigid and precise, it will be slower when used as a plotter. Motors are used to move the things that travel along the axes. A special driver moves the motors and a microcontroller that interprets the data sent by the host computer commands the driver. The parts used in the construction include several springs & pieces of plastics, power supplies, shaft-matching carriages, precision hardened shafts, timing belts & tension pulleys, and 2 bipolar stepper motors. The axes are shown in the images below.

To carry out pen movement and pressure, the pen carriage must be rigid enough as shown below along with a technical drawing. For less inertia and higher speeds, being lightweight is preferred. It is basically a lever where a cam mounted on a shaft of an RC servo pushes the short side. This setup lifts up the pen when servo pushes and the pen-side of the lever is pulled down by the weight of the pen plus the force of the spring when servo doesn’t push. While keeping it simple, this allows for some adjustments in pen pressure.

Salvaged bipolar motors with large step angles are used by Motori and they are driven by a special driving circuit consisting of two A3984 micro-stepping drivers. Only micro-step forward/backward and hold position can be done by the motor drivers. The data coming from the host PC requires a microcontroller for interpretation and translation into low-level step commands for the motor drivers. This is an ATmega644 with the right amount of RAM, program memory, I/O pins, etc. The proverbial ULN2803 in DIP package switches 4 of other high-voltage actuators and connectors are provided for the stepper motors, the servo, and end switches. A power supply from one of the cannibalized printers is used to provide power for logic and motors.

During the stages of development, some drawings were produced by Motori as shown below.