10:1 Herringbone Cycloid Gearbox

thingiverse

I am the proud owner of two irreversibly crashed RC helicopters with main drive gears stripped due to their extremely low quality. Fortunately, the motors remained intact despite the wreckage. I wondered what could be done with these damaged copters, perhaps transforming them into a new RC vehicle equipped with a better control board and sturdy frame. Intrigued by this possibility, I set out to create a mini 10:1 cycloid gearbox using printed gears that would withstand some punishment. The resulting device is a herringbone cycloid, an innovative design that may be a world first. It consists of four key components: Firstly, the flat platform with stub attaches directly to the motor. Secondly, the cam is connected to the motor shaft and firmly secured inside a 625 bearing using a clever jamming mechanism. The cam's width increases towards its bottom edge, ensuring it stays put. Thirdly, the output gear holds the 625 bearing in place. As the motor rotates, it causes the bearing to wobble in a circular motion within the output gear. However, a slider on the side prevents the output gear from turning, forcing it to rotate instead. A small bolt with a washer keeps everything securely fastened. Lastly, the output wheel is fitted onto the fixed gear and features a 7x3x3 bearing that centers it perfectly on the motor shaft. This precise centering allows the gearbox to move smoothly rather than wobbling aimlessly. A thin layer of masking tape helps secure the output wheel in place by snugly fitting onto the motor's 2mm bore. The output gear is intentionally designed to be a bit tricky to attach to the fixed gear, requiring some force and finesse to get it to stay on during operation. To make installation easier, I recommend greasing the gears with white lithium before assembling them. Please note that this gearbox is only intended for counter-clockwise rotation. Attempting to use it in the opposite direction may result in jamming or other issues. To create a clockwise version of this gearbox, simply mirror both gears on either X or Y axes. I have successfully printed and tested this gearbox, which produces a satisfying mini chainsaw sound as it operates. However, I had to epoxy the shaft to the cam due to some initial issues with movement. If your printing tolerances are different from mine, you may experience gear seizure or unexpected detachment. This is still a work-in-progress, and I'm not yet satisfied with its performance. One notable issue remains: the output rotational speed is not constant, which might be acceptable since the blades will likely be free-moving in the final application. Unfortunately, I don't know what type of motor this gearbox was designed for, as there are no markings on it at all. If you're looking to replicate this project, the screws are spaced 17mm apart, and the motor is from a Sanhuan 8827 RC Helicopter (also known as Pioneer X8 or simply "piece of trash" due to its tendency to spin wildly and plummet).