A couple of notes for you since you are 3D printing from your models.
Likely you’ll want to model at a larger size. When I model for printing I set the model units to meters and enter either mm or inches as appropriate. For example this crank handle for a drill press is supposed to be 95mm long.
Working that large allows you to create small details.
Here’s a grab of it in the slicer. It needs to have some support added to it, of course. This was just as an example.
If your slicer will let you define the import units you don’t even need to scale the model down before exporting. There are some slicers that don’t give you the option to set units, though. If yours is like that you will need to scale the model down before export.
As for the smoothness of the parts, here’s a comparison with the crank. The motor support bracket in the next images was modeled with smaller faces to get smoother surfaces. They are still faceted but it’s not as noticeable as on the crank handle.
