Remember the goal is to crush then grains so that your hot wort is able to access the inner most corners and extract sugar from it. Powdering the grains will only lead to flour that will be hard to deal with.
Secondly crushed grains are sticky (malted grains have higher sugar content) and needs to be preserved from moisture esp. monsoons to extract the maximum flavors and aromas. If you are not using grains within a week of crushing, then better to make breakfast porridge out of them instead of beer.
Thirdly if you are making a nice big batch, it is best to hunt down a nearby flour mill. Request them for the daliya setting (broken wheat) and coarsely get the grains crushed. You can use your mixer or coffee grinder as well for a small batch (provided you don't make a powder out of them) Otherwise if you have rolling stones, mortar and grain mill, then nothing is better.