Since I last posted I got 5 quarts of cream from my milk man that had hits its sell-by date. I cultured it all into sour cream, reserved a quart to use as such, and turned the rest into butter in my very inexpensive food processor with the steel blade. worked great! Worked better if it was no more than half full. Used it to wash the butter, too, adding fresh water and pulsing a few times.
Dave in CT