An OTF Knife, also known as an out-the-front knife, sliding knife, or telescoping knife, is a pocketknife with a blade that opens and closes through a hole in one end of the handle. Contrast this with the majority of knives, which are either standard folding knives or are “fixed blade” sheath knives (having no mechanical operation).(wikipedia)
John Heisz put together a wooden knife that pops out like any old switchblade and it’s pretty neat. He sands the wooden blade down and grinds it like you would any other knife and the end result is such a beautiful piece.
The “U” shaped parts only move a short distance under spring power, and that is supposed to provide enough force to propel the blade all the way forward or all the way back. This relies on the mass of the blade and momentum.
To lock the blade in the forward (open) position, or the back (closed) position, there are wooden springs that engage with the end of the blade when it’s open, and a notch in the blade when it’s closed.