I made one of these irons years ago to cut into a bad laptop battery pack, and fix it. it was so handy ive nearly used it up, Flaws in my first design were that i used a very flimsy iron, and so sometimes i have to bend it back a bit if im cutting with too much pressure.



I was seeing someone elses instructable the other day and realized i should document how to make a hot knife1



This can be simple or tricky depending on the soldering iron you have.



this green one i used was not ideal, because the tip was threaded and screwed in, A better iron would be one with a single screw on the side that lets you pull the tip out if loosened. So I had to modify my iron a little. (I will annotate that as I go)



Step one, unscrew the blade/jaws/gripper from the handle on a cheapo Exacto knife, set the blade off to the side.



Step two, remove your soldering iron tip from the iron. If it s the kind with a screw on the side loosen the screw and pull it out. The tip might be long or short, does not really matter. just pull it out set it aside, (might want it if you ever want to turn it back)



*If its a threaded tip Soldering iron like the green one in the photos, hopefully its the same threads as the blade holder on the exacto. mine did not it was smaller, so i had to cut the threads a little bigger.



Step 3, where the irons tip was, insert the blade holder and grip of the exacto into the iron, and slightly tighten the screw (the one that held in the tip of the iron)



Step 4, put the blade into the exacto holder, if its loose, turn the holder clockwise a little bit, so that the threads on the blade holder spin past the screw, once its tight, tighten the screw to keep it in place.



step 5, find a nice safe surface to heat it on, (i have spare tiles from a bathroom remodel I can set it on as i plug it in.



Reminder, its now very sharp, and will soon be very hot!







