Engineer versus the Rat 2014

Continuing on from yesterday, I went through all this just about 3 years ago and have been here before that too. This time I do not have a workshop at my disposal, but still reluctant to spend money on a commercial trap. I am an engineer, it just doesn’t feel right. So here we go.

I scanned around the kitchen, to see what materials that I had available. The only suitable container was a 1.5Ltr water bottle. I found string, sate sticks, rubber bands and a few rudimentary tools sufficient to work the materials.

Mk1 – A snap shut affair, based on bottle traps seen on the web. By not cutting all the way through the bottle, I was able to use the bottle material as the hinge. Sate sticks pushed through the body and the lid and connected with rubber bands to fire the trap. String tied to the lid to hold open, bait tied to stick, poked through hole from inside. String looped around stick from outside. Done.

The bottle material was round and so flimsy, that it collapsed under the load of the rubber band – failed.

Mk2 – I liked the basic design, it just needed refining. This time I cut the cone completely off and tied it back on in reverse, so when it snapped shut, the cone held the shape of the bottle. Running the elastic through the centre of the bottle and through the bottle cap, also helped to hold the shape. Everything else the same.

This design worked, but there was room for improvement. The cap tended to catch when hinging shut, so trimming the lid geometry required more planning. The elastic passed through the centre of the bottle, which looked like it inhibited the rat’s access and could prematurely fire the trap. Also, the double rubber band was too tight, inhibiting the firing bait stick – to be improved.

Mk3 – Used a soldering iron to melt all the holes. This speeded up the construction and actually strengthened the holes with a rim of melted material. A common bait and elastic hole at edge of bottle, this runs the elastic out of the way, along the side of the bottle. A single rubber band, just strong enough. Poke bait stick through same hole.

This is a slick design, using readily available materials at zero cost. Construction time is a few minutes and no need to re-use. Just submerge in a bucket of water to extinguish the rat. Tie off in a plastic bag and dispose – this should work.

Mk4 – one more concern, that the rat could bite through the rubber band and release itself. A trimmed length of 6mm diameter plastic tube would be a future modification, but we’ll see how Mk3 goes for now.

The trap looks twisted and distorted. But, once it fires, the cone inserting into the tube, straightens everything out and the trap is solid. Rats are stronger than you think, but the slippery surface gives the rat no purchase to be able to push the lid open.

Dave