As long as you use either the milling blade or the extractor blade in the NutriBullet the Nutribullet will work just fine for grinding coffee beans.
The Nutribullet is a very versatile machine and works great for processing foods and grinding up coffee beans.
I used to use a regular blender to grind coffee beans but now that I have a Nutribullet I use the Nutribullet with the milling blade to grind my coffee beans.
I find that the Nutribullet does even better at grinding coffee beans than an actual coffee bean grinder.
I use my Nutribullet a lot and recommend them to anyone needing a good food processor.
It's a powerful machine as well and well worth the cost.