3D printer and CNC basics lesson plan
Learn what a printer’s firmware does underneath: homing, temperature control with safety, G-code motion and runout detection.
Objectives and materials
By the end, students can
- Find zero with an endstop, then move two axes from G-code lines.
- Hold a heater at temperature, catch a loose sensor and pause for empty spools.
Materials for the whole unit
- Arduino Uno R3
- Filament lamp
- Full-size breadboard
- LED
- Limit switch, lever microswitch x 2
- MOSFET
- Photo interrupter, slot
- Piezo speaker
- Pushbutton
- Resistor x 4
- Slide switch
- Stepper driver, A4988 x 2
- Stepper motor, NEMA 17 x 2
- Thermistor, 10k NTC
Every part is already on the simulator’s bench, so there is nothing to buy or hand out. The counts are the most any one lesson uses, if you build it on real breadboards too.
Motion
Find zero with an endstop, then move two axes from G-code lines.
| Lesson | Time | What students do |
|---|---|---|
| Stepper homingHow a printer finds zero: an A4988, a NEMA 17 and an endstop, a fast seek, a back-off and a slow second touch, then moves inside software limits. | 60 min |
|
| A mini G-code interpreterSend G28, G0, G1 and M114 to a two-axis plotter line by line, and see what a firmware does with each one: home, interpolate, report, answer ok. | 60 min |
|
Materials
- Arduino Uno R3
- Limit switch, lever microswitch x 2
- Stepper driver, A4988 x 2
- Stepper motor, NEMA 17 x 2
Check for understanding
Each student finishes "A mini G-code interpreter" on their own, without opening the hints. The simulator checks 4 of its 4 steps as they go.
Then ask each one to explain, in a sentence or two, the last thing it asked of them: "A straight diagonal".
Printing safely
Hold a heater at temperature, catch a loose sensor and pause for empty spools.
| Lesson | Time | What students do |
|---|---|---|
| Heated bed PID and thermal runawayA thermistor, a MOSFET and a PID loop that hold a bed at temperature, and the protection that switches the heater off when the reading stops following it. | 60 min |
|
| A filament runout sensorAn optical runout sensor, a debounce, the filament still in the path after the sensor, and a pause that waits for new filament and a press of resume. | 60 min |
|
Materials
- Arduino Uno R3
- Filament lamp
- Full-size breadboard
- LED
- MOSFET
- Photo interrupter, slot
- Piezo speaker
- Pushbutton
- Resistor x 4
- Slide switch
- Stepper driver, A4988
- Stepper motor, NEMA 17
- Thermistor, 10k NTC
Check for understanding
Each student finishes "A filament runout sensor" on their own, without opening the hints. The simulator checks 4 of its 4 steps as they go.
Then ask each one to explain, in a sentence or two, the last thing it asked of them: "Reload and resume".
Teach this unit as a class
Start a class from this course and its 4 lessons are assigned in one go, in order. Students join with a six-character code or printed login cards, and each one’s work comes back to you.
The class tools are free for 30 days for one class of up to 20 students, with no card. The lessons themselves are free either way.