Removing the transformer from old microwaves and repurposing it for other projects like spot welding, pyrography (wood burning), or any other high-power applications can be extremely dangerous and should be avoided for several reasons:
High Voltage: Microwaves use high-voltage transformers to step up the voltage from the standard household voltage (usually 120V in the US) to the much higher voltage required to power the magnetron (the device that generates the microwaves). The output voltage of the transformer can be lethal and cause severe electric shocks if mishandled or accidentally touched.
Electric Shock: When working with the transformer and associated components inside the microwave, there is a risk of electric shock even if the microwave is unplugged. Capacitors in the microwave can store an electrical charge even after the power is disconnected, and accidental contact can lead to shocks.
Fire Hazard: The transformers and other electrical components inside the microwave are designed to handle specific power levels and currents related to microwave operation. Repurposing them for applications like spot welding or pyrography may result in excessive currents and cause overheating or even electrical fires.
Lack of Safety Features: Microwaves are designed with safety features that prevent them from operating when the door is open or when the magnetron is not securely in place. Repurposing the transformer outside of its intended use may remove these safety mechanisms, making it more hazardous.
Inadequate Design: Transformers in microwaves are not specifically designed for spot welding or pyrography applications. Using them for such purposes can lead to inefficiencies and unsafe operating conditions.
Legal and Insurance Issues: Repurposing microwaves for unintended purposes might be in violation of local regulations or warranties. Additionally, if any accidents or damages occur while using modified equipment, insurance companies might not cover the costs.
In conclusion, attempting to repurpose the transformer from a microwave for other high-power projects is not recommended due to the significant safety risks involved. It's crucial to prioritize safety and use appropriate, purpose-built equipment for any intended applications. If you need equipment for spot welding or pyrography, consider investing in tools that are designed and built specifically for those purposes to ensure both safety and optimal performance.