This is a gear cover for an Atlas lathe made in 1935.
My old Atlas came without a cover for the gears. Looking on the internet, I found pictures of covers, and I even bought one on Ebay -- only to find it was too small, presumably made for a smaller version of the lathe. So I modeled one and printed it out. I included photos here of the source covers. They are obviously different from the model provided here.
Due to the unusual shape and the way it was modeled in OpenSCAD, rendering of this object is very slow with CGAL (F6), (the quick render with F5 rendering was OK.) It was not unusual to take an hour or more for 1 part. Because the size was too large to fit on my printer, I divided it up into 6 pieces and then added parts to screw them together. My OpenSCAD would repeatedly crash when trying to render the piece with the connecting parts. So I had to render them separate, then import into Blender, and unite them there. I have saved the resulting STL's from that process.
The sides are not completely smooth, and I suspect an expert at Blender could greatly reduce the polygon count of the object. I tried to figure it out, but was unable.
For finishing, I applied several coats of XTC-3D to fill in the gaps, then painted with an enamel-based paint.
The support arm clamps onto a ledge along the side of the lathe. This is the same as the method used in the original cover. There will be substantial torque on this arm, so I would recommend printing with at least 80% infill. The OpenSCAD file includes the option to print out a bolt for the arm, but I would recommend using metal bolts instead.
There is currently no provision for latching the cover closed. I will probably add that as a separate part in the future and glue or screw it to the cover.
While designing the cover, I needed a model of the actual lathe gears so I could ensure everything fit. I include that here, though it was never intended to be printed.