I was struggling putting this idler bearing in a design I was working on to upgrade my y-idler plate on my Makerfarm Prusa i3v and came up with this idea. It is probably not a new idea, but was new to me. I made a 3d printed M5 plastic shaft the same length as the 2 washers & 2 split bearings & put them together outside the belt tensioning part. I then slid it into place & pushed the M5 screw thru the hole pushing the plastic shaft out. Sure made it simple to put that together. I made a .5mm thick slot the same size as the plastic washers in the part I was sliding into so it was positioned correctly. Here are some photos.
Slick