How to make a marble run your kids (and their science teacher) will love
Mission: Construct a marble run with your child and use it as an opportunity to teach them about science and technology.
Real mission: Construct a marble run with (or without) your child. Beat the other kids. Beat the other kids’ parents. Beat everyone.
Only kidding… (not really).
Marble runs are a school science project classic - like rubber band cars and spaghetti and marshmallow towers, they are something every parent (and child) should make at least once.
Now you make one
Yes, you can cobble together cardboard boxes and toilet roll tubes, but for me you’ve got to get the marble running along tracks, and for that you need something more sturdy.
I normally start with a wooden base and build the tracks from wire, but for the project shown in the video above, I used wooden dowel for the tracks - it worked well and was much quicker to assemble.
The instructions below are intended as a guide and inspiration – they don’t cover every step of the build, this one is a little too complex for that!
I used MDF board to create the stand, but any wood will do. Cut a large section (600mm x 800mm) for the upright board and a small section to create the horizontal base, use nails or screws to attach them, as shown in the illustration.
Wooden dowel (6mm diameter) is great for making marble tracks and is much easier to work with than wire. You'll also need a flat strip of wood 6mm x 25mm (cross-section) to make the track supports.
To make the track supports cut a small section from the flat strip of wood, about 35mm long, and use hot glue to attach one of the long edges to the front of the stand.
The dowel tracks will run across these supports, so use two (or more) of them along the length of where you want the track to run - remember, ensure a gentle decline otherwise the marble won’t run!
Now, cut two equal lengths of dowel and glue them onto the track supports. The first against the stand, and the other slightly less than the diameter of the marble away. Use the illustration for reference.
Make a small tin box (use tin snips to cut up an old biscuit tin!) and attach it to an L-shaped wire arm. Drill a hole in the front of the stand and push the wire arm through, you may also need to add a small wood ‘spacer’ to stop the tin box rubbing on the front surface of the stand (follow illustration).
Push the wire through the hole. On the reverse side of the stand use hot glue to attach a thin wooden arm (the counter balance). Glue coins on the arm until the weight of the marble rolling into the tin box is just enough to tip the arm over.
Make a clip from a rectangular strip of tin folded in half. Glue it onto the front of the stand, using another wood spacer to position it accurately - it needs to stop the box falling backwards after it goes past.
Create a tin ‘lift’ using more scraps from the biscuit tin. The lift needs to be attached to string and a counter weight, use the illustration as reference. The trick is in creating a catch that will release the lift when the marble rolls into it. For this, cut a long strip of tin and use pliers to make a ‘ridge’ across it. Make a corresponding ’ridge’ on the lift - it must be able to hook under the ridge in the tin strip. Adjust the tin strip until the force of a marble hitting it is enough to release the lift.
Go your own way
If you don’t have the tools, time or materials to build a marble run using wood or wire - don’t let me put you off going the ‘cardboard box’ route. In fact, this approach does have one advantage, the easier construction method means the kids can get more involved.