Now tighten it down. CAUTION: Don’t use long screws. You wouldn’t want a screw accidentally digging into the wire inside the handle. This would cause current to take a short cut through the screw and bypass the coil.
The Pencil in Action
To use the pencil, all you have to do is connect the pencil to the 6-volt (or 12-volt) battery and then run a line from the battery to the part, using the clamp to hold the line on.
Make sure the area to be “branded” is clean, bare metal. This means no rust, grease, paint, or clear lacquer.
When writing, use a light touch. To get the best perfor- mance you’ll probably have to make slight bending adjust- ments to the arm to get the right clearance between bolt and screw. If the clearance is too large, the electromagnetic force won’t pull the screw in. If the clearance is too small, the screw won’t have enough room to vibrate properly.
But once you’re set up, the sparks should fly nicely. The inscription will be rather fine. So if you want the letters to be wider, you’ll have to do some retracing.