Our 3D printed electric screwdriver worked well enough, but had some serious wobble because of instability between the servo itself, the couplers, and the bit holder holding the screwdriver itself.
Pressure being transferred to the servo was also a concern. We had glued the servo-bit coupler to the 608zz bearing. But hot glue gives under pressure and eventually the servo would be taking any pressure placed on the bit.
A redesign of everything included using two 608zz bearings, a new coupler that integrates the bit holder instead of connecting to it. The bit holder also physically rests on the bearings, and the bearings rest on the bearing housing, meaning no pressure will ever be placed on the servo itself, with or without glue.
Because the new bit holder is shorter, despite putting an extra bearing and spacer into the design, it is not that much longer. The spacer could even be a little smaller, making the housing and overall length shorter as well. Let's see how this design works and maybe if future changes are made, the design can be shortened as well.
All the files and details on assembling this project are available on Thingiverse here.
Follow ProgressTH.org on Facebook here, Instagram here, or on Twitter here. We also put all of our 3D printed models online for free at Thingiverse.com here.
