This project started with some idle chatter with some guys I used to work with. Eric had this idea for a "slinky machine", which would essentially become an escalator on which a slinky continuously descends. Years passed and I occasionally teased Eric about it. Eventually, I figured he'd never build it and it was fair game for me to do it.
I started with a slinky from Walmart and experimented with how high and how wide the steps needed to be for a slinky to descend. 10 cm of height and width per step seemed to be enough.
I rigged together a staircase to make sure this step size would work. It was tricky to launch the slinky, but once launched, it usually made it all the way down. I leaned the steps slightly away from me, with a backer board on the other side to keep the slinky on track.
Next I needed to build a wooden chain, or track, for the steps to attach to. One end of each link has two notches cut out, the other a part in the middle cut out.
Then some holes drilled in the ends so that nails can be inserted from either side to act as a hinge.
Assembling the chain to make sure it works.
Then making steps to attach to the links. I cut these from some pieces of 2x4 cut at a 45 degree angle.
I drilled some screw holes in the links, then screwed the blocks on.
The link chain, resting on a board, for further testing. It was tricky, but I could get the slinky to walk all the way down.
I made two square "sprockets" for the chain to run on. The square shape is enough to drive the chain, though it runs a bit rough.
I used my lowest speed drill to turn the shaft for some testing.
Launching the slinky, then starting the drill at just the right (very slow) speed was tricky, though I did manage to get the slinky going for maybe ten seconds a few times.
Mostly though, the slinky kept tumbling off in random directions, once even ejecting over the top when I ran the drill too fast.
One of the more successful runs with a drill.
I mentioned how difficult it was to control the speed to Rachel, and she said "Why don't you just use a crank?" May be I have been watching too many Izzy Swan videos on YouTube. Not everything needs to be powered with a drill!
The crank made it easier to control. Also more fun.
But it's still a challenge keeping the slinky running without falling off. Cranking it at the right speed is the easy part. Starting the slinky right is quite hard, and if it's not launched just right it goes off track quickly.
My plan had originally been to motorize and automate the slinky machine, but it's not reliable enough to run on its own, so a cranking it by hand makes more sense. Also, my hand cranked marble machine 2 is at least as fun as the motorized marble machine 1