I decided to try the Metal Gear System Extruder
I ordered a kit online from http://www.reprapsource.com/en/show/6770
The web site put a scary amount of shipping cost to New Zealand, so I contacted the site owner on #reprap and he was happy to send it via normal post (3.45 EUR) , with the understanding there was no insurance or tracking. I went with this option.
Here are all the parts, as pictured on the site.
Plus some plastics I prepared earlier
It is reasonably easy to assemble but also the main shaft is a bit fiddly
Now the issues:
The mount is for a X carriage with 24mm hole spacing, the standard Prusa I3 has hole spacings of 30mm. They do provide stl files for their own X carriage, but the two lm8uu's and single lm8uu where swapped over. I didn't want to completely rebuild my X axis just to move one lm8uu.
This is still listed as experimental, as I haven’t actually mounted it on the I3 yet.
The new hole isn't on the extruder, I used the mount as a drill guide and drilled a new hole.
If I have assembled it correctly. I am one m3 nut short and one m3 bolt short.
This is probably for a different extruder mounting system
I'm fairly sure I have it assembled correctly, now I'm going to pull it apart again,
The main drive gear on the stepper only over laps the large gear by about 1 mm, I think it should have more contact, so I am going to move it a fraction.