Alumimaker 2

Video of it printing here: https://youtu.be/bAI9mNnLWFo . I still had a bit of wiring to clean up, and I'll be reprinting the blower fan mounts in black. There's also a little bit of stringing; I was still tuning the retraction.

This is an Ultimaker 2 derivative called the Alumimaker 2. It includes several design improvements, but most importantly, being made with 2020 extrusion, it is easy to modify and expand the build volume (easiest in Z, but also easy in X and Y.) I decided to design this because the Ultimaker 2 has received great reviews, I wanted to experiment with their motion system, and I wanted a system that I could easily upgrade to dual extrusion. This printer uses a number of stock Ultimaker 2 parts, leveraging a known good design.

Improvements
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- Easily modifiable/upgradable chasis
- More rigid frame
- Direct drive motors eliminate compounded backlash in X & Y
- Grub screws on radial bearings eliminate linear shaft displacement
- Improved electroni