Canadian Woodworking

One fun marble run

Author: Rob Brown
marble run

This column rounds out exactly one year of weekly posts (as long as you give me a pass for the week off leading up to Christmas), and I just realized today I have yet to mention a small, portable marble run I made with my son almost two years ago.

This simple marble run isn’t to be confused with the larger marble run we worked on about a year ago, that (full disclosure) still isn’t done.

Right around two years ago we got to work on a fairly simple, yet super fun, marble run. Probably the main reason this was a successful project was because we didn’t set our sights too high, and kept the project small enough to remain portable. This meant we had only so much surface area to play with, and we wouldn’t allow this marble run to drag on forever.

marble run

Mission Complete – Our completed marble run, in all its glory.

We searched the internet to come up with some fun ideas, snapped a few screen shots, then headed to the shop. We grabbed a piece of scrap 3/4″ particleboard that wasn’t too big nor too small. Gravity works top down, so that’s where we started. A few standard ramps to “get the ball rolling” and we had momentum on our side.

A Full Run – It starts off slowly, but picks up speed along the way. A good run ends at the floor, in a controlled manner. A poor run often ends near the Plinko screws, as the marble bounces off the run.

Three ramps were enough, and we decided to direct the marble around to the back side of the board. Curves require something a bit different; either a curved piece of wood needs to be cut or you have to incorporate a piece of recycled material into your run. We chose the later, and got to work cutting the lid of a Rustoleum aerosol spray can to fit our requirements. We attached it to a plywood base, smoothed the transitions, formed a hole in the particle core base to bring the marble back to the front of the marble run and off we went.

The Upper Half – Here’s a closer look at the upper half of the run.

It was at this point we thought a choose-your-own-adventure was what our marble needed, and set up a series of screws for the marble to bounce down. If you remember Plinko from “The Price Is Right”, you get the picture. In doing so, the marble either leaned left or right and landed on a ramp that further directed the little ball.

A Right Turn at the Plinko Screws – Music to our ears, as the marble bounces its way down slats of different lengths.

If the ball went right, it bounced down a level and tapped the tops of a series of rungs, making different notes as it went. In our minds the notes the marble played were loud and clear, like the New York Philharmonic. In reality, the notes were quickly played and off tone. We liked the ugly song it played, though. And because we drilled holes in the tops of the slats that fit over the nails, we could reposition the slats to get a different ugly song. A short ramp led the marble to my son’s favourite part of the run – the jump.

A Left Turn at the Plinko Screws – Smooth, rhythmic travels down the finishing nails is a lot of fun to watch and hear

Challenging Nails – Although we did shift the particleboard backer on its side to check how different angles worked, it was hard to keep it steady to get a good test done. In the end, we used trial and error to find the final angle, while keeping the nails very close together.

Tricky angle

Okay, back to the Plinko screw maze, where the marble could choose its own adventure. If the marble went left instead, it moved down a set of closely spaced finishing nails, making a very pleasing sound. The three levels of nails work nicely now, but they were not easy to make. We knew the nails needed to be spaced close together so the marbles wouldn’t bounce, but the angle gave us lots of problems.

 

We started off with the nails at far too shallow of an angle, so the marbles didn’t travel down the nails. Next, we increased the angle. Far too much, apparently, as the marble bounced wildly down the row of nails. We decreased the angle, only to find out the angle was still too steep. Our fourth time was a charm, as once we nailed the angle of the nails the sound the marble made when it moved over each row of nails was truly music to our ears. Smooth, rhythmic music, with virtually no wild bouncing. We took that angle and ran with it to add the next two rows. This is my favourite part of the run.

 

The jump was a bit of a challenge, as the ball kept flying into the hanging slat above it, not to mention flying too far over the landing container we built for it. After a few adjustments, everything worked fine. We then directed the marble around to the back, through a hole in the particleboard base. If you watch the run from the front, the marble magically appears at the other side of the run, then works its way down a few more ramps, onto the floor and hits a block cut at 45° to send it away from the run.

Short Ramps – If you look closely, you’ll see a short ramp filed into the end of the surface, directing the ball into the hole in the backer board. These details direct the marble and give it a short downhill slope to roll down.

Sounds pretty good, eh? It was! It was also pretty frustrating at points, and continues to be, almost two years later. You only get a clean run (where the marble doesn’t fall off the run) about two-thirds of the time. When things do go wrong the marble likely doesn’t make it through the screw maze without bouncing off the run entirely. The next likely culprit is the marble doesn’t make it through one of the holes in the particleboard base, and gets stuck behind the board.

Grooves – A groove to help center the marble, then direct it through the hole, was needed in the container that catches the marble after the jump.

The devil is in the details

Marbles have a way of finding the tiniest sharp edge to hang up on. Even a bit of dust can cause problems. All the corners, holes and transitions in this marble run had to be smoothed and shaped so the marble could smoothly navigate its way down to the floor. This took some patience. A few times we had to hand-shape grooves into the wooden transitions do ensure the ball entered a hole properly.

Stop Blocks – And once the marble goes over the jump, gets captured by the container and rolls along the groove we added, it needed to be further directed and controlled so it rolled along the track. A small wooden block was added to the far side of the track to stop the marble from overshooting the track.

And when the marble bounces, we had to ensure the landing area was ready to catch the marble as nicely as possible, or at least contain the bouncing and regain control of the marble as quickly as possible. We added small walls to contain a bouncing marble, added chamfers to ramps to keep the marble moving smoothly and did many more things. Trial and error was the name of the game, as the marble quickly told us where the weaknesses were.

Angle Them – Slightly angled surfaces, so the marble doesn’t fall off the run, are important. This is the case for the ends of the removable slats and any flat tracks. Even the finishing nails were all driven in at a slight angle.
Add Chamfers – Because the marble is moving fast when it hits the jump launch track, we had to heavily chamfer one side of the groove to better contain it. This allowed the marble to sit lower in the groove, while the outer edge of the groove was left unchamfered, to stop it from going overboard.

Things to do differently next time

If I were to do this sort of thing again, I’d make the ramps slightly steeper so the marble travelled a bit faster. I think the level of difficulty we built to was perfect for my eight-year old son but adding more moving parts would have been fun. There are so many ideas on the internet, not to mention the fact that once you get into a project like this ideas just start coming to you as long as your imagination is open.

Building both woodworking and logic skills

We obviously used many woodworking tools and techniques while building this run. Machining grooves, trimming parts to length, cutting curves on the bandsaw, drilling holes, hammering in nails and driving screws were just the tip of the iceberg. And working through what to do was also challenging, yet very satisfying.

 

I was glad we didn’t try to make this into a huge project, as I think my son’s attention span would have been pushed beyond his limits. If he were a few years older we could have done something larger, but the trick with kids is knowing when enough is enough.

 

I was lucky enough to be able to bring this marble run to my son’s Grade 3 class so he could show his classmates what he’d built. (This was before COVID.) He was very proud of his project, as was I. Our trip to his class was the icing on the cake.

 

Have you ever made a marble run? If so, please send me a few photos or a video of it in action. I’d love to share it with our readers.

More from Rob on marbles




Published:
Last modified: January 16, 2022

Rob Brown - [email protected]

Rob is a studio furniture maker and the editor at Canadian Woodworking & Home Improvement.

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