Hot Wire Cutter, Part II

The original hot wire cutter setup used an extension spring to tension the wire in a wood frame. This worked, but the spring simply was not stiff enough to fully tension the wire during cutting- which left scallop marks on the foam as the wire formed a curve as it cut. I removed the spring, then tried cutting again. This time it was very obvious how much the wire sags when it heats! Take a look at these photos and video:

Before heating wire: (at roughly the center of the wire)

 

After heating wire:

Major saggage! Even more compelling, check out this video:



So, before I make Rev2 of the speedwing I'll be adding a higher K factor spring to this hot wire cutter.