Poor man's gear box for post processing 3D prints

thingiverse

For sanding and polishing 3D printed plastic parts, high speed "dremel style" tools can hardly be used at 10000rpm. I designed a poor man's gear box reducing speed a factor of 6 or so. It fits with the "Cotech" brand (in Sweden found at "Clas Ohlson" stores, equivalent tools exists under other brand names) with an additional bit chuck and an additional flexible extender. Using it, I can easily sand, cut using diamond tools, and polish the items without overheating the plastic. However, try it with care, and be sure to assemble the parts correctly. I couldn't resist from using the beautiful "Gear Bearing" by Emmet (from 2013, please see https://www.thingiverse.com/thing:53451 for the original item) when designing this item. Please note, the small pin (white in the picture with the gear box partly dismounted) will lock the chuck to the main part. The large cogwheel will then lock the pin, and the red top will finally lock the large cogwheel.