EMC2 Bipedal Robot Joint - 53.6 Gear Ratio

thingiverse

EMC2 Bipedal Robot Joint / Compound Planetary Gearbox. Ring gears are all replaceable, might have to file down the tabs in order to get it to fit. Bevel gears and concept created by Richard Ramos. Specs: - Gearbox ratio: 53.6:1 - Dual gearbox ratio: 107.2:1 - Planet gear teeth: 17-15 - Sun gear teeth: 15-17 - Ring gear teeth: 50 - Driven gear teeth: 48 - Motor shaft compatibility: Nema 23 - Screws: M3 25mm Use washers inbetween the bearing and the 48-ring-gear-holder to avoid excessive friction. Use a horizontal expansion of at least -0.1 or -0.2 to print the bearings. (-0.2 for most cheap printers). https://youtu.be/4kfm5-gb3KI https://www.youtube.com/watch?v=KA73O2ilDlo To-do list: - Replace 3d printed needle bearings with similarly sized 4.5mm steel bb ball bearings - Add 4.5mm ball bearings to the neck of the 15 sun - 24 bevel - 15 sun gear joint, held in place by the centre ring. - Add 4.5mm ball bearings to the neck of the 12 bevel gear, held in place by the opening of the centre ring. - 24 bevel gear should be replaced with a 31 bevel gear. This will require you to also widen the centre ring in order to make space for it. - Use STM32F103 module to run the stepper motors at 1/4 - 1/8 microstepping while also quadrupling your maximum speed and keeping noise to the minimum. - Integrate limit switches at the bearings in order to add homing/position-reset capability. I haven't tested it yet, but if the STM32F103 does indeed allow us to obtain higher speeds at high microsteps, then you will effectively be able to use stepper motors as a BLDC replacement, with almost zero noise. This is because the amount of steps you can produce with an individual arduino Nano is limited by its processing power (stm32 uses ARM cortex-m3 microprocessors) Don't waste your money on fancy stepper drivers that claim to be 'silent', they still require you to run at high microsteps to get the least amount of noise. Keep in mind that BLDC motors are at least 3-5x more expensive than stepper motors. I'm not using steppers just to be edgy, I'm using them because they're super cheap, and they get the job done. DC motors are also another possibility, but then you'll need to integrate rotary encoders, and also use much higher gear ratios. Unfortunately this would also mean having to run fragile 3d printed gears at much higher speeds, reducing their life expectancy in the process. I rest my case: Stepper motors are King