MakerBot Print is our newest print-prepration software, which supports native CAD files and STL assemblies,
allows you to interact with all your printers via the Cloud, and many other exciting new features.
The first one I printed was too loose as well, but that was because my E-steps were too low and I was under extruding. After calibrating my E-steps and flowrate with the help of this guide from Mattshubs, the second one came out absolutely perfect. Enough tolerance to be a push fit yet it grips the leadscrew well.
FWIW, the first one has a 8.08 to 8.15mm bore and my lead screw measures 7.96mm, so scaling to 98% would have made it fit. In case you for some reason don't care about accuracy or correct tolerances but just want a part that fits.