SG90 mini robot arm S9 by FrN (Robot Arm for everyone!)

thingiverse

Here is a US10 dollars DIY mini-robot which designed for HK student. It uses the most common SG90 mini-servo motors and was powered by Ardurino Pro-mini or Nano. Each servo have added a different step-down gear to increase the torque and reduce the speed to a reason manner. Engineering Notes: - The waist servo have a speed reduction of 1:2 and 90 degree of rotation. - The upper arm servo have a speed reduction of 1:3 and 60 degree of rotation. - The lower arm servo have a speed reduction of 1:4 and 45 degree of rotation. - The base turning servo have a speed reduction of 1:5 and had extended the servo 5K VR from the servo in order to provide sufficient torque and 180 degree angle of rotation. - Six 4mm dia metal ball are required to support the base turning gear. - All servo motors are using the same gear of 9 teeth. This gear of 6 different tolerance/clearances are provided. Enjoy! Demo: https://www.youtube.com/watch?v=EqWLwB4PkA4 Where to buy? 20mm shaft: https://item.taobao.com/item.htm?spm=a1z09.2.0.0.38a12e8deTecbK&id=548322518504&_u=52bdisfs539b 90,180,360 degree SG90 servo: https://item.taobao.com/item.htm?spm=a1z09.2.0.0.36822e8d82V8ZH&id=39560573589&_u=52bdisfs41e7 4mm ball bearing: https://item.taobao.com/item.htm?spm=a1z09.2.0.0.36822e8d82V8ZH&id=549201779704&_u=52bdisfs8819