Introduction: How to Make a Plastic Cutting Hot Knife

If you 3D print or work at all with plastic, you will eventually need to trim or cut through a part. The easiest way is heat up a blade and slice the plastic. This is best way I've found to build a hot knife to cut plastic.


Step 1: Disassemble the Exacto Knife and Remove Tip From Soldering Iron

Loosen the screw on the soldering iron and pull the tip out. Unscrew the barrel of the exacto knife and remove from handle.

Step 2: Assemble the Knife

  1. Insert the barrel of the exacto knife into the barrel of the soldering iron.
  2. Tighten down - be sure to tighten from the side of the blade to hold the blade tight.

Step 3: Heat Up the Iron and Cut Plastic

Plug in the iron and let it heat up. The higher the wattage to the iron, the easier it will be to cut plastic.

Cut slowly, you are melting through the plastic with a thin blade.