I use McMaster-Carr to find and import models for all sorts of mechanical items; from gears to stepper motors to screws.

Go here: https://www.mcmaster.com/pillow-block-bearings

Find what you want and click on the part number. When window opens, click "Product Detail"
Scroll down to the drawing and you'll find a drop down selection box. Select: 3D Step
Click Save. The model then opens in MoI

Ed Ferguson