LEGO grasp Grant Davis got here up with a easy concept: construct a LEGO machine that mimics the DVD emblem screensaver, a nostalgic picture from the late Nineteen Nineties and early 2000s that glinted throughout numerous TV screens.
Most bear in mind the brand transferring at a continuing tempo, reversing on affect after which persevering with to bounce across the display. To translate this into an actual LEGO construction, a mechanism that may reverse immediately was wanted. His first try, utilizing a round gear system, failed. The brand slowed because it hit the wall and slowly backed away, as a substitute of snapping again just like the screensaver. After some thought, Davis went to LEGO treads, the tank-like tracks discovered on excavator units. By attaching the brand to a tire looped round particular gears, he may get a extra genuine bounce with a constant tempo and pause on the wall’s edge.
Constructing the DVD emblem required a design that was each recognizable and purposeful throughout the limits of LEGO bricks. So, a simplified model of the brand was required, with curved slope items forming the disc form, rounded tiles for the “D” letters and little slope items for the “V”.
The body, powered by a single LEGO Technic motor, grew to become a battle of stability vs performance. Early variations wobbled because the treads moved, so Davis enclosed them in a cage of bricks and Technic beams to cut back flex. Lengthy axles linked the 4 treads – two for horizontal movement and two for vertical – so a single motor may energy the entire system. The brand bounced just a few occasions earlier than the machine failed, which meant Davis had a troublesome resolution to make: keep on with the treads or attempt a brand new method.
LEGO worm gears, a chunk formed like a worm wrapped round an axle, claimed extra management by rotating a flat gear up and down with every flip. Davis noticed potential, however hit a snag: worm gears solely transfer in a single route, regardless of the motor’s spin. To get the brand to bounce forwards and backwards just like the screensaver, he wanted a tool to mechanically reverse the motor. His first try used a gearbox with two blue gears spinning in reverse instructions, which had been switched by a grey piece to rotate the axle. Davis tried thicker rubber bands, after which a LEGO swap that reversed the motor immediately. It labored, however with a tiny delay when it went into the “off” place.
This had him going again to his gearbox design and refining it to take away friction. He moved the rubber bands to drag from the facet, so they might toggle easily even at full pace. The consequence was an prompt route change, identical to the screensaver’s snap. Levers that toggled the mechanism when the brand reached the highest or backside of its path had been added to make it a hands-free course of.
Scaling as much as a full-size TV offered new challenges as a result of Davis wished a 16:9 facet ratio like a contemporary flatscreen, which meant worm gears on all 4 sides. The bigger construction required stronger helps, particularly throughout a 60-stud hole on the prime. He used plates flipped on their sides for stability, however forgot to depart room for the toggle mechanisms, so he needed to do some last-minute “cosmetic surgery” to unencumber some area.
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