Small thumbwheel for bed leveling

Small 18mm thumbwheels from manually adjusting beds on assorted derivative i3 kit printers. [Replaces smaller metal thumbscrew nuts and wing nuts](https://youtu.be/PNEnV7rsIJA) but should not bump into anything.

An M3 screw has a 0.5mm thread pitch when means a full turned of a bed leveling nut moved the bed 0.5mm. Two turns would be a full millimeter. The thumbwheel I designed has 10 points on it so every point is 0.05mm height change. Two points would move that corner of the bed up or down 0.1 mm.

I created another [thumbwheel design](http://www.thingiverse.com/thing:915845) that is too big for some of my newer i3 kits.

This thumbwheel works well with Tronxy X3, Zonestar P802M, Anet A8, and a few other i3 kits.

If you find this useful, please encourage me with a tip.

UPDATE: added a new version with the numbers in reverse per maker's correct logic: small_thumbwheel_rev2.stl