The Marble Run Game
39245 Rapid Prototyping Project 2
Samuel Chinn, schinn
Kevin Frey, kfrey
Allen Jiang, yuanj1
Description of the Toy: This toy was designed as a new take on the usual marble run game. We wanted to incorporate a design that differed from the usual interlocking track design. Our toy uses track pieces that fit into a pegboard rather than into each other, enabling more stability and fewer parts. A pinball-like mechanism moves the ball back to the designated starting place and gravity takes care of the rest. The pieces are designed to teach children about angles and help in refining motor skills and problem-solving.
Marble Tracks: 3D-printed tracks are able to be inserted on the pegboard. A huge semi-circular support part was also printed in the printer, and we had to cut it apart from the track so we can use it.
Pegboard: This is an 18’’*24’’ wooden board with of laser-cut holes. One can see three neighboring holes made at 60-degree angles. The holes were spaced at one inch apart vertically and horizontally.
The Pin and the Wooden Track: We first designed it as a 3D-printed part, but transitioned to a bandsawed wooden pieces with a spring that shoots like a game of pinball. We changed approaches because it was more cost effective and easier to manufacture. It moves the marble all the way up from the bottom to the top of the wooden track on the left side of the board, so the marbles can start rolling through the inserted printed tracks. Note the wooden track ends up being taller than the board so the marble can fall into the tracks.
The Bottom Ramp: Basically a ramp that blocks the marble so they don’t roll out of the board, and that makes the marble roll back towards the ‘launching position’ at the bottom left corner of the board so we can use the pin to shoot it back to the top again.
The Process: During the creation of our toy product, we ran into several issues that needed troubleshooting. After laser cutting the pegboard and inserting some of our 3D printed pieces, we quickly realized we would need to adjust the height of the board so that the marble would be able to roll smoothly in and out of the track pieces, which were about ⅛” above the plane of the board. To address this, we raised the height of the return track on the left side of the board and created a ramped piece of wood that the marble could roll up to get to this height.
Another issue we had to solve involved the top left of the pegboard – the location at which the marble had to transition from the return track to the pegboard itself. The spring mechanism would shoot the marble up the return track, only to have it hit the wall and roll back down. To fix this, we had to carefully position angled wooden pieces that directly the marble to the pegboard. Although the marble sometimes still rolls back down the return track, these adjustments have significantly improved the success rate.
Potential Improvements: The positions of the holes made it hard for the 3D-printed tracks to line up and reduces the number of ways the tracks can be inserted. Neighboring holes make up isosceles triangles with a base length of 1’’, a height of 1’’ and thus equal side lengths of 5’’, but if they form equilateral triangles, those problems mentioned above may be solved. In fact, due to such imperfect positioning of the holes, some printed tracks failed to line up with each other.
The size of the holes, and therefore the radii of the cylindrical pegs at the bottom of the tracks that enable those tracks to be inserted onto the board, may not be large enough. This makes those pegs kind of long and thin, and more susceptible to friction with the hole walls and to bending. In fact, after lots of inserting and detaching, those pegs quickly become worn and black, and one cylinder was unfortunately broken when we tried to insert it into the hole.
Last but not least, as mentioned before, we 3D-printed a pin at first before replacing it as the more effect wooden bandsawed one; we didn’t make the bottom ramp tall enough so when the marble is rolling towards the bottom very fast, it has so much momentum that the ramp failed to block it successfully–the marble just rolled out of the board. Later when we doubled the ramp height, we met much less such trouble. Besides, we also didn’t add walls at the right end of the board, another position where the marbles may roll out of the board from.
