Curtain Gear + Gearbox v2

prusaprinters

Enhancement on my previous Curtain Gear project due to multiple shortcomings, using the carrier (planet fixer) to drive the output with a higher torque, and having the ring fixed against the NEMA17 motor.  Modify the source file if you have different dimensions.WarningSignificant tweaking is still required on this model! I've given up on trying to make it work due to some friction, gearing, shearing, and tolerance problems. Said problems have significantly decreased the output torque, or have made the mechanism unstable. So I've decided to buy a metal gearbox for NEMA17 from StepperOnline and save myself the headache from hereon in.Dimensional InformationCurtain CordOEM, 4mm diameter balls connected by 2mm of stringNEMA17 Motor5mm D-shaft (0.5mm inset). With a 9mm long cylindrical shaft before the D chamfer begins. (L = 40mm). With my calipers, I've found that the depth of the M3 mounting holes are 5.5mm, but I've designed it around a 5mm depth.Herringbone Gearbox7:5:17 gearbox with the torque step-up of 2.4x. Backlash is minimal due to improved tolerance testing, both on the D-shaft and within the herringbone gears.Curtain Gear22 slots with 0.25mm tolerance. Gear radius of 21mm and outer diameter of 44mm. Which means it is barely larger than the profile of a NEMA17 motor (42.3mm wide). PhysicsInput Torque (of NEMA17): 44Ncm@24V1.68ARadius of the Curtain Gear: 21mmTheoretical Angular Force Output (at 21mm): 55NDistance between the center point of the planets and the gearbox: 12.3mmThe carrier moves at 7/24 the rate of the sun gear. (ie. ~686 steps per revolution.)Changes on previous designUses the Planet Carrier as output instead of the Ring, increasing the torqueRemoved the motor mount / carrier fixing hubRing is now mounted directly on the NEMA17, reducing the sizeFixed a bunch of tolerance issuesUses ball bearings now (since I'm using the planet carrier as the output)Bill of MaterialsNEMA17 (1703HS168A) Stepper Motor x1623-2RS Ball Bearing (ID3, OD10, H4) x6M3 35mm Screws x7M3 Nuts x6