Spot welder

The video about my DIY spot welder.

About the spot welder

Figure 1:
For further experiments with my Direct Granule Extruder, I need to join thin sheets of metal with spot welds. This is why I created this very simple, but sufficiently good spot welder.

Mechanics

Figure 2:
The mechanism consists of 3D printed parts, 6mm brass tubes with soldered 3mm copper wires and an M3 screw as a swivel joint.

Electronics

Figure 3:
In terms of electronics, all that's needed is a supercapacitor and a step-down converter. The capacitor has a capacitance of 325F and a maximum voltage of 2.7V.
The step-down converter is connected to the 12V line of an old computer power supply and set to an output voltage of 2V.

Assembly

Figure 4:
The capacitor is soldered to the two brass tubes of the pliers using wires that are as short and thick as possible. A very high current must flow during welding, and the energy supplied from the capacitor should not be dissipated on the supply lines.
When connecting the step-down converter, note the correct polarity of the capacitor!

Figure 5:

Figure 6:

Figure 7:

Figure 9:

Welds

Figure 10:
For my purposes, I need to join tin cans with a material thickness of 0.15mm. Charging the capacitor to approximately 2.0V produces very good results. With a charging time of approximately 2 minutes between two points, this simple device is not suitable for frequent welders - at the very least, you should consider a more powerful step-down converter. The capacitor can be charged up to a voltage of 2.5V (avoiding the 2.7V limit). If you need to weld sheets that aren't weldable with this method, a capacitor with a higher capacity can be installed. It's important to keep in mind that thicker sheets require more stable mechanics. The two sheets must be pressed together firmly during welding.

Download

The 3D files are available as a download package.

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