The mouse gap squeezer teaser machine
Following my smallest hole for a mouse experiments last year, I still wanted to test how narrow gap (as opposed to round hole) a mouse could still get through. It's easy to adjust such a gap, and even better if the computer can adjust it. Lego is ideal for making this sort of mechanism, and if I use Lego, I might as well build the whole experiment out of Lego. I'm using my old (1st generation) Lego mindstorms kit, which I previously used for this pager rotating machine for my old job at Blackberry. And yes, work paid for the Lego.
The motor is controlled from my Raspberry Pi board, using a relay board that plugs into it. I added some limit switches to stop the motor when the sliding door reaches either end. There's no feedback for the door position to the computer.
I set this up in a little shed next to the garage at our house. This isn't as good a location as the shed I used when we lived in the country, but there is at least one mouse that showed up after I left some cardboard with Nutella smeared onto it.
I made a short vlog video about setting this up.
A reader had sent me these point to point wireless antennas for getting internet to the big garage workshop in the country. I had set these up, but decided to keep using the old ethernet cable I strung to the shop at least until it failed, and it never did fail. But for this they turned out very handy because I didn't have a good place to string an ethernet wire and this is out of range for the house's wifi. I would have had to leave a window open a crack and string the cable across where the kids like to play otherwise.
Eventually I decided to detect "mouse in box" by just looking for a slight reduction in average brightness inside the box. This feature was easiest to hack into my imgcomp program that I used to run the experiments and record imagery.
The smallest gap the mouse was able to get through was about 1.5 Lego studs. Lego studs are spaced 8 mm, so this worked out to 12 mm.
After it got too tight, the mouse tried to chew the gap open a bit, but those Lego bricks are much harder to chew than wood. I kind of figured I would be sacrificing a few Lego bricks to the experiment.
Though shrews (another mouse sized creature) seem to be much more determined and more flexible based on previous experiments, but I didn't have one of those show up for this experiment. I strictly use wild mice outside who come and go as they please.
Mouse experiment setup vlog (2018)
Mouse in a Lego maze (2019)
Jumping wild circus mouse (2020)
Mouse trap maze experiments (2016)
My imgcomp program (motion triggered time-lapses)
Raspberry pi computer holder (2015)
Lego contraptions (1996)
machine XL (2014)
To my Woodworking website.