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Marble run generator Pro

A tower of tilted trays a ball rolls down, simulated so it runs when you cut it.

Open Marble run in the app Pro generator: explore its settings in the app; cut files come with the Pro plan (coming soon).
A laser-cut marble run: a tower of tilted trays held between two slotted side plates

In short: A tower of tilted trays: a steel ball rolls down one and drops onto the next. The slope, the drops and where each ball lands are worked out and checked, so it runs.

A tower of tilted trays held between two slotted posts. A steel ball (or a marble) rolls down one tray, drops off its low end onto the next, which slopes the other way, and so on to the bottom.

Marble runs from a template often fail in the same places: the ball overshoots a tray or hops over the back wall. This generator simulates the ball rolling, tipping over each edge and falling, and places every tray so the ball lands on it, with margin for a ball that leaves faster or slower than expected. Stop walls are tall enough to catch a ball that bounces. Layouts that would not work are refused rather than drawn. The 3D preview plays the run in real time.

Add the crank lift and a paddle wheel carries the ball from the bottom back to the top, so it keeps going while someone turns the handle.

You need: plywood, a steel ball of the size you set, glue, and for the lift two 6 mm dowels.

Settings

All of these can be changed in the app, and the 3D preview updates as you type. The name under each setting is its key in a share link, e.g. https://laserpuzzle.app/app/#/marble-run?ball_diameter=…; a link only needs the settings that differ from the defaults.

Run

SettingDefaultWhat it does
Ball diameter
ball_diameter		16 mmMeasured diameter of the steel ball or marble. From 6 to 30 mm.
Trays
trays		5Each tray is one run of the ball, back and forth. From 2 to 10.
Tray length
tray_length		160 mmLength of a tray along its slope. From 60 to 400 mm.
Slope
slope		4%Height lost per 100 mm along the tray. A steel ball needs about 2 to 6 per cent: less and it stalls, more and it flies too far to land cleanly. From 1 to 12 %.
Channel play
channel_play		3 mmChannel width is the ball plus this. Too tight and it jams; too wide and it zigzags. From 1 to 8 mm.
Gap between trays
tray_gap		8 mmFree space between a tray and the one below it. From 5 to 40 mm.

Lift

SettingDefaultWhat it does
Crank lift
lift		offA paddle wheel turned by a crank carries the ball from the last tray back up to the first. Needs an even number of trays.

Plus the material and machine settings every generator has: material thickness, kerf, slot clearance, sheet width, sheet height, part spacing, engrave part labels, cut line colour, engrave line colour.

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