Summary of Building a Sentry Gun with Laser Trip Wire System and Arduino
This project by Singapore Polytechnic students involves building a laser-triggered sentry gun using basic soldering and metalwork skills. The system fires a toy gun when a laser beam is interrupted by an intruder. The frame is constructed from metal sheets bent and drilled into specified shapes and sizes to hold servos and the toy gun. Key components include continuous rotation servos for rotating the gun and a servo for triggering the gun. The assembly includes a base, gun support, turning panel, and servo mounts, all integrated with an Arduino and electronic components for the laser tripwire system.
Parts used in the Laser-Triggered Sentry Gun Project:
- Toy Gun (preferably semi-auto)
- Continuous Rotation Servo Motor
- Servo Motor
- Servo Arms and Wheels
- Arduino
- Metal Sheets (cut into various specified sizes)
- Ball Bearings
- Bolts
- Nuts
- Screws
- Rubber Washers
- Cable Tie
- Copper Wire
- Copper Strip Board
- Pins
- Sockets
- Resistors (1K Ohm)
- Light Dependent Resistor (LDR)
- Potentiometer (20K Ohm)
- NPN Transistor (2N2222)
*NOTE* THIS PROJECT IS DONE BY A GROUP OF STUDENTS FROM SINGAPORE POLYTECHNIC.
Concept:
Trigger gun when laser is blocked by intruding object.
Note:
Tilting is included for expandability but not used in this project.
Skill Level:
Basic soldering and basic metal works
Things You Need:
Toy Gun(Any will do, preferably a semi-auto)
Continuous Rotation Servo Motor
Servo Motor
Servo Arms and Wheels
Arduino
Metal Sheets
Ball Bearings
Bolts
Nuts
Screws
Rubber Washers
Cable Tie
Copper Wire
Copper Strip Board
Pins
Sockets
Resistors(1K Ohm)
Light Dependent Resistor
Potentiometer(20K Ohm)
NPN Transistor(2N2222)
Step 1: Building the Frame
Cut the metal sheets into 6 rectangular pieces(4 of equal length, 1 long, 1 short) and 2 square pieces.
Below are the dimensions we used:
4x 6”(inch) by 2”
1x 10.5” by 2.4”
1x 2.5” by 2.4”
1x 10” by 10”
1x 9” by 9”
Feet(6” by 2”):
Bend the 4 metal piece 90 degrees at the 2” mark and make screw holes(at least 2) at the shorter end.
[Image 1]
Base(9” by 9”):
Make screw holes that match your feet’s at 4 corners of the metal piece to mount the feet and a hole in the center for the pivot(the hole size depend the bolt you’re using).
[Image 2]
Gun Support(10.5” by 2.4”):
Bend the metal piece 90 degrees at the 2” mark and the 6.5” mark to form a deformed U. Make screw holes(at least 2) at shorter end and 4 holes at the other end to mount your servo.
[Image 3]
Turning Panel(10” by 10”):
Make screw holes that match the gun support’s at one corner of the metal piece and one hole in the center for the pivot(should be slightly larger than the pivot but smaller than your ball bearings).
[Image 4]
Servo Mount(2.5” by 2.4”):
Make a hole at one end to fit into the pivot and 4 holes at the other end to mount your servo.
[Image 5]
Step 2: Trigger of the Gun
Mount one of the servo to trigger the gun
We secure a small servo with a short servo arm onto toygun.
Step 3: Putting Everything Together part 1
Mount the gun onto a continuous rotation servo[Image 1].
Secure it onto the gun support[Image 2 & 3].
Secure another continuous rotation servo with wheels[Image 4] onto the servo mount[Image 5 & 6].
For more detail: Building a Sentry Gun with Laser Trip Wire System and Arduino
