2.5"ø Mecanum Roller Wheel Design:
The rollers are male/female interference fit, no hardware required. There are (7) pairs of male/female rollers per wheel, total (4) wheel assembly will require (28) pairs.Roller pairs press together and bottom out leaving clearance on hub and spin freely. Wheel hub has right/left variations with a 0.50"ø hole in the center for custom hub (will post the hub I use for a nema 17 stepper soon). The hub's back face is 0.50" offset from the center line of the wheel and the overall width is ~1.30" with a rolling diameter of 2.50". Full STEP file assemblies are in the download section.
I printed this in PLA with a touching bed support incline of 48° for the hubs and 14 male/female roller pairs with out raft or brim on glass (ext 215°c bed 60° with light adhesive spray).
Currently, I'm working on designing & building a fully 3D printed mecanum wheel robot as a test bed for learning stepper motors, controls, then ultimately wireless controls and operation with arduino platforms. This will be a work in progress for the next few months as I modify my requirements.
04/03/16: Added Nema17 wheel hub.