Hot wire foam cutter

Step 9 Applying tension

Insert a ruler or dowel in the tesioning loop and twist it until it seems to be getting a little tight. Careful not to twist too much or you'll break the wire or the frame. Pluck the wire and listen for a musical tone. If it sounds like "fwubababa" it needs more tension. If it sort of hums it should be enough to start. You can always add more if it seems too floppy when you try to make your cuts. Once you are happy with the tension, slide the ruler or dowel down so that the yardstick keeps it from unwinding (see the photo).

You'll have to readjust the tension later, after the wire gets hot for the first time. Or maybe every time.