This instructable explains how to make a spot welder from a MOT (microwave oven transformer).
The primary coil (thick wire) will still be used as primary windings. The secondary coil (thin wire) will be replaced with very thick wire of less windings.
Do NOT plug in this transformer before it's ready. Especially not when the original secondary windings are still in there! This device outputs an extremely deadly high voltage. You have been warned!
Also, as in all my other instructables, read all warning notes! I'm not responsible for any accidents.
Step 1: Requirements
- 3 female slide connectors (not required, you can also solder the wires)
- wall plug with ground terminal
- cutting pliers
- drill with thick iron drill bit (10mm or so)
- iron handsaw
- wood saw or jig-saw
- 1m thick 2 gauge flexible wire (1 meter) (if you don't have this, check step 5)
- a volt-meter (or multimeter)
- a wooden shelf (see step 7)
- some other small wooden pieces (see step 6 and 9)
Step 2: Removing the secondary windings
This seems to be the best way to do it:
- recover any slide connectors (picture 1)
- saw off the windings as far as you can without damaging the primary windings (picture 2)
- take a 10mm iron drill bit and drill a few holes trough the windings (picture 2)
- do not damage the iron core of the transformer
- use long nose pliers, a hammer and a screwdriver, or whatever it takes to remove the secondary windings
- remove the two magnetic shunts (picture 3 and 4)
- clean up the hole you've made
The other steps will be easier, don't worry.