We’ve been wanting to make a pulley for a while now.
I’m not quite sure when exactly the fascination started, but it’s been going for a few months at least. Every time my daughter Jewel asked if we could make one, I couldn’t help but think “Yes, we should to get onto that. We’ll need to look up what to do, and make a trip to the hardware store to gather some supplies, including one of those fancy pulley wheel thingies. But right now we have abc and xyz going on. So we’ll look into it later. Soon…”
To be honest, I’d turned it into something that felt a bit daunting.
I’m not necessarily afraid of daunting. But with other things creating busy-ness in our lives, daunting made it easy to keep putting our pulley off until some fictional future time when we’d have plenty of time to research, plan and gather supplies.
But then I realised… it really doesn’t have to be that complicated. By definition, pulleys are a simple machine, after all!
I realised that we don’t have to make the world’s best pulley on our first attempt. In fact, coming up with an OK (but slightly flawed) pulley might actually open up discussions about pulley design, and how we could improve it. So, along those lines, designing an imperfect pulley is probably more educational than coming up with the perfect pulley in the first place… Don’t you think?
So anyway, that’s the back story behind our pulley design. We used what we had on hand, and we just gave it a go.
And, wouldn’t you know, it actually works! (Mostly…)
How we Made Our Pulley
- A chopstick
- An empty cardboard ribbon spool
- Two pails
- Adhesive tack
It took just a few minutes to make this pulley, including gathering the materials. (So much for daunting!)
The kids and I made it together. We decided to place it on the stairs, so the kids could use it to help carry things up and down the stairs.
We inserted the chopstick through the hole in the middle of the ribbon spool, and then attached both ends of the chopstick to the stair railings, so that the chopstick was secured horizontally. We are lucky that our stair railings taper slightly so I could tie on the chopstick without it slipping down. (If you don’t have railings like this, you might need to use tape or another method to secure the chopsticks in place.)
We tied the end of a piece of rope to the handle of a little pail, and threaded the other end over the ribbon spool and down the other side.
We noticed that our ribbon spool wobbled because the hole in the spool was larger than the diameter of the chopstick, so we added adhesive tack to both sides of the spool, to stop it sliding around too much.
Learning about pulleys through play
The kids discovered they could use the pulley to raise or lower the pail by pulling on, or releasing, small sections of rope. Of course, all manner of items then had to be carried up and down the stairs! Lots of dolls travelled in the “lift”, as well as LEGO bricks, jigsaw pieces, pens and pencils, and lots of other small things.
Heavier items were harder to lift, hold steady, or lower slowly. If you let go of the rope, the bucket would crash to the floor.
After a while, we added another pail to the opposite end of the rope. This doubled the efficiency – while one bucket was carrying items up, another could be carrying items back down!
The kids noticed that with two pails, when the pails contained similar weights, the pulley balanced itself out. It only moved when someone pulled on a section of rope, and otherwise remained stationary. It was just as easy to lift light or heavy loads, provided the pails were balanced.
But when the buckets were uneven, the heavier bucket would “pull itself” towards the floor unless someone was holding the rope to stop it.
I should mention that our pulley design isn’t flawless. The adhesive tack helps steady it a little, but the ribbon spool still does wobble (especially when being played with vigorously), which can cause the rope to slip off the spool. The rope also slips off the spool if the buckets are lifted up (which creates slack in the line). But I’d say in general it works well enough for a quick DIY and a first try!
We’re hoping to try out a few design modifications to see if we can improve on our design. Watch this space!
For more physics fun, you might also like:
- how to make a simple balance scale
- how to make an easy upcycled catapult
- STEM Challenge – can you build a 3D structure
- here’s an easy refraction of light activity (that you can try almost anywhere)
- or find all our fun physics ideas here