Alright, a quick update for you guys. After a host of testing I'm still not happy with the current performance of the printer. Thus I am in the process of doing a revision 2.5. The 2 major changes I am looking at are replacing the pulleys and changing the gear profile. I think the scaled up STL gear profile I used is not accurate enough and is a major contributer to inaccuracies in the print.
To address this I have taken the time to CAD up my own herringbone involute gear profile with a 45 degree pressure angle. The profile is parameterized so I can easily change the number of teeth pitch and pressure angle by just altering three parameters. I'm in the process of printing and testing a 40 tooth 125mm pitch gear and am going to test how accurate I am at holding center to center distance. I'll report back with results soon.
Additionally I have found an ideal replacement candidate for the 623v pulleys. They can be purchased through amazon:
http://www.amazon.com/FORWORD-10pcs-Pri ... ge_o00_s00I have bought 50 of these and their quality isn't even comparable to the 623v pulleys because they are just so much smoother with zero wobble. At $15 for 10 they are a bit more pricey but well worth the cost vs. performance benefits here. I just strung up an arm with them and it moves like butter. I'd say by hand it has about 25% of the friction resistance as compared to the 623v arms when I try to back-drive them. Their outer and inner diameter is about 1mm larger than the 623v but they are the same width (slightly thinner really as the 623vs have are wider than spec). This means we will need to use m4 screws as pulley axles as well so 'll have to size up the holes appropriately.
A big github commit should be coming very soon once I finalize and clean all the changes. Keep an eye out!