CNC 1610 Z carriage

I managed to strip the bolt for tightening the spindle on my Linksprite 1610 CNC. I decided to take the time to model up an entire replacement carriage (with help from [a few measurements](https://www.thingiverse.com/thing:2748598)).

Features:

1. the carriage is entirely parametric.

2. It features a lifted spindle clamp to increase clamping surface when using an ER11 collet, which tends to be longer than the stock collet.

3. it uses a [GoPro knob](https://www.thingiverse.com/thing:16