As told by Montey Rasmussen (born 1951)
We put our fresh, unpasteurized, raw cream straight from the refrigerator into our Bosch bread mixer, attach the wire whip, and turn it on. The mixer first turns it into whip cream then after a couple of minutes it rather abruptly separates into butter and buttermilk.
For the last minute or so I have to hold the lid down tight on the mixer as buttermilk is flying everywhere. It takes about 5 minutes to do this.
With this type of high speed mixer it isn't necessary to let the cream sour. I think the fresh cream makes much better butter. After I turn off the mixer and take off the lid, I pour most of the buttermilk out of the side of the bowl and collect the butter. The majority of the butter is wrapped up in the wire whips that I flip out.
We get the buttermilk out of the butter and wash it much like the instructions above for the old time recipe. However, as I work the butter I try to keep it as cool as I can as working the butter when it is too warm will mess things up. I've even put ice cubes in the water to cool things off without damaging the butter. When our butter is finished, we put it in a margarine container and put it in the refrigerator.