The regular blender will work just fine for grinding coffee beans if you like your coffee beans ground to a medium to fine grind.
Just run the coffee beans through the blender for a few minutes or so until the beans are ground to the type of grind you want it too.
If you want a different grind on the coffee beans then you would need to use a regular coffee grinder to get those better results.
But I have used a blender to grind coffee beans before and it worked just fine for me.
So if you do not have a coffee grinder and don't want to buy one then a blender will work great for grinding coffee beans.
The blender does nearly the same thing as the coffee bean grinder although you may have to just allow it a few more minutes to blend and grind the coffee beans to the grind you want.