Using 1.75mm Filament on Ultimaker 2
The guide below is for the Ultimaker 2 (old version) extruders. NOT for our Ultimaker 2+ extruders, unless modified to clamp down further.
YES, it IS possible, but PLEASE read the following guide first and follow the steps rigorously.
They also provide a nice printable PDF for download which is handy to have at your side.