A really fun first marble run with a Grimm’s Rainbow is the classic setup with all the arches lined up (don’t you love the sound?!)—but it doesn’t take many additional sets to increase the challenge and excitement.
For these Marble Runs you'll need to the following sets:
- Grimms Large Rainbow
- Grimms Building Boards
- Grimms Semicircles
- Grimms Wooden Balls or Grimms Small Balls
By adding the Grimms building boards to the same run, you add a vertical drop to the run so that once you get it rolling it keeps the momentum (goes a little faster!), and the sound is more resonant.
To make it easy to use even for a very small child, I put the smallest board in the dark blue arch, and then the next size up in each of the next arches. Nesting the boards inside the rainbows gives an edge for the ball to bump against so you don’t lose the ball off the edges of the run.
To make the run less wobbly, (this is helpful particularly if you have little people), wedge the two left-over longest building boards against one side of the run.
This run can be used with any size Grimm’s ball, but we ran it with the large balls. The small balls ran well too, but the marbles took quite a lot of “oomph” to have enough momentum to get to the end of the run.
If you want to take that same run and make it just a little bit fancier, you still don’t need to add more sets—you can take the same run, remove the blue and purple pieces, re-arrange the boards on the floor, and make a track that returns the ball to the start:
Here’s the top view, both with and without the rainbow arches in place. The two largest boards are now underneath the rainbow at an angle, decreasing the space between them as you get closer to the purple bumpers. This very slightly decreases the speed the ball moves down the boards, but not enough to notice. The ball will bump off the purple arches, but then with the combination of the remaining momentum and the slope created by the building board wedge, the ball should roll all the way back to the start.
This run is a little bit more delicate than the first one, and it runs best with the Grimm’s “small balls”. The bigger balls bumped the purple arches out of the way, and the marbles didn’t have enough momentum to finish the run.
I love the melody this one makes!
If you want to move on to a new level of complication, the semi-circles are a great addition. They can give you a lot of height and are great surfaces for the balls to roll on. This one was easy for my 7-year-old to mimic, and after he built it, he had fun modifying and adding to it.
Any time the marble path changes direction, its important to ensure that the track is lined up, and it isn’t always intuitive.
The first transition happens as the ball comes off the top board into the arch of the red (2nd biggest) rainbow arch. The ball comes in at a gentle angle so that it can pick up the directinon of the curve without loosing too much momentum, but not so slight that it misses the first portion of the arch. Also notice that the red arch overhangs the edge of the semi-circle just a bit to help “catch” the ball.
The next transition is a little trickier to set up and took a couple of adjustments to get right. The trick is to remember that the ball will follow the trajectory of the last part of the rainbow—it doesn’t continue to curve, but will go straight in the direction it leaves. The red arch overhangs the semi-circle on this edge too, to help control the direction.
The last transition follows the same principal: as long as you have your board set up so that the marble follows the straight trajectory of the last part of the rainbow, your ball should stay on the board. Thes red and orange arches are not adjacent in the rainbow, but skip one (the light red) to create a space between them for the ball to roll on)
Here is the whole run from the top:
This one ran best with the “small balls” as well:
This last run is still made with only the rainbow, the semicircles and the building boards.
It used every arch from the rainbow, and the semicircles and boards on the left side of this picture.
The more complex the marble run is, the more it helps to start building at the end, and slowly work your way up (testing as you go) it really helps to manage the speed and momentum, and make sure the ball stays on the track.
All the height in this run is created using the rainbow arches with semi-circles stacked on top.
This is the bottom level. Notice how the yellow arch is slightly offset from its semi-circle, to help catch the ball as it rolls in:
Next add three semi-circles, the biggest and smallest arches as shown:
Then the building boards, two as ramps, one to stop the ball at the end of the run. Notice that where the ends of the ramps are balanced on arches, it always has at least two points of contact to help keep it stable:
And fully assembled, from the top. The top red arch is actually the 2nd biggest arch in the rainbow, but sitting on top of the biggest semi-circle board for extra wiggle room. As you set it up, pay attention to the trajectory established each time the ball leaves an arch!
From this angle you can see how the pieces line up:
This is another run for the medium-sized balls.