I made these belt guides to keep them from slipping off of the Printrbot's 624 bearings. Especially helpful if you're using longer belts (like for the XL bed), or if your bearings aren't exactly aligned.
Both print very quickly, but I'm only using the X belt guide right now (the other one is for Y, even though it isn't labeled as such). They should both work, however.
I forgot to take pictures during installation, but it should be pretty straightforward! Refer to the Instructions tab.
I printed mine at 0.1 mm layer height. Seems to work fine at 15% infill, but you can print it denser if you'd like. They are only 1 mm thick, so it shouldn't take long at all.
On the Simple 1405, the 624 bearings should have been mounted with a single washer against the head of the M4 screw and two washers against the frame. The belt guides will be used in place of the single washer, sitting between the M4 screw head and the 624 bearing.
It is a little tedious to disassemble the printer to install these, but in my opinion very worth the trouble.