This is a set of accessory parts for the Atlas change gears. (See also here: https://www.thingiverse.com/thing:143893)
The gear lock is the part that links the rotation of one gear to another. I have not yet tested all of these in use, and I am not sure if 3D printed plastic will be strong enough. Probably should be printed in ABS etc. The bushing goes inside the gear lock. The bolt goes through the bushing. I suspect that plastic will not be strong enough, but it was easy enough to model, so I included here. I printed my bushing in nylon, and it works great.
The drive screw support is a copy of the original part for holding the far (distal) end of the drive screw to the bed. This part is supposed to be a bit weak, so that if the carriage crashes into the headstock, it can break away and prevent further damage to the lathe. I include an .stl that is an exact modeling of the original part, and another with support. HOWEVER, I found, esp when milling threads, that 3D printed version of the original part was not rigid enough (printed with nylon), causing the carriage movement to be non-smooth. I changed to the beefy version and have not had any further problems.
NOTE: These parts need to be somewhat precise in their fit with each other and with the gears. I included a printer_tolerance parameter in the OpenSCAD file. Users may need to adjust this for their particular printer so that the actual measurement after printing matches the desired size, compensating for the inherent inaccuracy of the 3D printing process.
NOTE 2: The gear lock size was modeled from original part that came from my lathe. However, I found that the 3D printed gears (see link above) were often thicker than original gears. This made the bushing and gear lock too short by 4.6 mm. I think that all the gears are not the same thickness, but I have not measured them all as of this writing. So others may have to fiddle with the code to change the bushing_gap variable to achieve the desired part thickness.