Geeetech G2s Upgrades

Superceeded by v2 at http://www.thingiverse.com/thing:2157448

This is a series of upgrades for the Geeetech G2s printer. The stock unit has a number of design issues that I wanted to address to get better prints.

The upgrades are printable parts, to be used with some sourced components.

I've included the master assembly as both STEP and native Fusion360.
Before printing, consider calibrating/compensating for material shrinkage. I've made a utility at http://www.thingiverse.com/thing:1982686 to assist in this - but use whatever method works for you.

1. New Carriages.
   The stock carriages use 2 cheaper bearings. The short contact length and slop results in a significant amount of play when the effector changes direction, putting torque on the carriage. In my case, I found this to be up to .300mm as measured by a good quality dial indicator when near to the towers. These new carriages show under .02mm deviation.
   These new carriages use 2 additional linear bearings. I used some Misumi LMU-N10 that I ordered from their website at https://us.misumi-ec.com/vona2/detail/110300026540/?HissuCode=LMU-N10. The carriages are designed to accept metal spheres with M3 studs, like the ones provided in the Magnetic arm kit (listed below).
2. Magnetic arms.
   The stock rod ends have 2 issues. First, they can't be exactly calibrated to the same length, due to the manufacture of the threads on the rod and rod ends (in my set anyway). I managed to get them close, but I wanted better. The rod ends also are fairly cheap, and it showed in the precision. I managed to get most of the slop out by center-punching the casing, but wasn't happy with these either.
   I decided to go with good magnetic arms:
   http://www.blueeaglelabs.com/products/haydns-carbon-fiber-arms-with-cnc-precision-machined-delrin-sockets
   These have excellent holding power, are very accurately calibrated, and the metal spheres ride in machined Delrin sockets (spheres included).
   I chose the 215mm length, which works perfectly for the G2s.
3. Effector and hotend.
   The Mk8 hotend was a pain to adjust the nozzles level, and limited the usable bed on an already small machine. I still wanted dual extrusion though, so I went with an E3D Cyclops: http://e3d-online.com/Cyclops. I added to this a 50mm blower fan for part cooling, as the stock unit is lacking this - a must as far as i'm concerned.
4. Extruder.
   The Cyclops hotend requires more force than the stock direct extruder can put out. I ordered 2 of the Greg's Wade Extruder hardware kit at https://www.ultibots.com/gregs-wade-extruder-hardware-kit/, and printed 2 sets of the extruder parts - 1 regular and 1 mirrored: http://www.thingiverse.com/thing:18379.
   In order to fit in the location of the original, you need to mirror one of the extruders. In doing so you need to reverse the hobbed bolt - to get the hobbed portion of the bolt aligned with the feeder tube, you'll need the attached spacer. In addition, the attached gear has a deeper relief to accept the bolt in the mirrored extruder.
5. FSR probing.
   I wanted a probe, but couldn't decide on inductive, capacitive, BLtouch, etc. Some work with glass, some don't... The FSR's are awesome. I ordered the FSR kit from: https://www.ultibots.com/fsr-kit/. As far as I can see, this is the best solution for probing on this type of machine.
6. Firmware.
   I upgraded to Repetier firmware, and really like it. The printer seems much smoother. If you plan to do these upgrades, let me know and i'll upload the correct configuration file.