I am looking into buying the V-slot 20mm gantry plate from the open builds parts website, but need an additional plate that can mount to it, and house a recessed bearing. The "C-Beam Motor Mount Plate" or the "Threaded Rod Plate" for the Nema 23 step motor both seem like good candidates, but do any of the pre drillled holes match up nicely with the gantry plate? I only have hand tools available so I would prefer to have something come prefabricated if possible.
Both should work but it really depends on how you need to mount them. I would suggest downloading the Sketchup parts files and checking the connectability graphically. There are also some pdf drawings available but unfortunately the listing isn't very current. Solidworks 2014 Parts Library (in a folder within the big download)