Quite some time ago I learned a little tip on the use of my blender that has saves me considerable time and mess while grinding my flax seed, hemp seed, oats, grains, and nuts etc. Until then, I had been using my coffee grinder for this task, which did the job well but was slow and messy. A large mason jar will fit most blender bases, in fact years ago, some blender models were actually sold with a mason jar included. You can add your seeds, oats or what ever, blend for a few seconds, then invert your jar, give a shake and blend some more so the seeds get evenly ground, unlike using the regular blender jar where the seeds just settle the bottom.
I eat ground flax seed every day, and while the simplest way to go is to buy already ground seed I prefer to buy mine whole. Grinding my own saves money, allows me to grind small amounts at a time to store in the fridge and I always have whole seeds on hand for recipes requiring them.
This method works really well for grinding oatmeal to make oat flour. I would not recommend grinding barley for barley flour as it is too hard on the blades. A grinding mill would be required for this task.
