Re: 16mm or 20mm , DIY CNC 60cmx50cm
Since you only have a fairly small cut area I would be inclined to go with a 5mm pitch. On my X axis (1200mm cut area, about 1700mm long) I have two 3210 ball screws (32mm / 10mm), on my Y axis (800mm cut area, about 1100mm long) I have a 2510 ball screw (25mm / 10mm) and on my Z axis (200mm cut area, about 500mm long) I have 2005 (20mm / 5mm).
So I would be inclined to go with 20mm, but you could get away with 16mm.
If my post is missing an 'nt you might have to add it yourself.