Planetary Gear Box for Small Stepper Motor

thingiverse

Update: crafted new 16 tooth GT2 gear head (6 to 7mm wide) for frequent small stepper motors. Developed a 4 to 1 planetary gear box for ordinary little stepper motors. It turns your common 7.5 degree per step motor into a 1.8 degree per step one. I possess numerous little stepper motors that I pulled from printers but the resolution was not satisfactory... so I designed this. Intend on creating more gear heads later to fit different belts/pulleys. READ INSTRUCTIONS! Print the Planetary and Sun gear at roughly 95% their standard size. It allows them to mesh better. Print all other components normally. Take a razor blade and trim a few things if necessary. I used acetone treatment on my parts which allowed me to stick the Sun gear (approximately 5 minutes after acetone treatment) onto the 2mm stepper shaft with a flat spot on it. I utilized a Dremel to grind a flat area. Another method is using JB Weld and a toothpick which fills in the flat section creating a snug fit. *Acetone treatment also caused the teeth to fade on the gear head... so I used Sugru and filled the empty slot, greased an ordinary printer belt, and turned the gearhead around it for form fitting. Let it sit for one day to dry then used a razor blade to remove any excess.* USE GREASE! Apply it to all gears, moving parts, and the bearing which holds the gear head. I utilized PTFE infused synthetic grease purchased from Enco.com for approximately 3 dollars on sale. It is incredible. Connected the prototype to a stepper motor tester (Arduino Uno and an A4988 driver) and ran it at 100 rpm for one day with no load. Still looked great. Specs: -4 to 1 gear ratio -M0.7 module on the case, planetary, and Sun gear -M0.3 for the gear head (fits ordinary printer belts) -Case has 39 teeth -Sun and Planetary are 13 teeth The stepper motor used was a Mitsumi M35SP-9T Q3066-60222, with a resistance of 10 ohms, and a rotation per step of 7.5 degrees at 2mm shaft diameter.