Q. Hi. I have a question that’s been bothering me for some time.
There are some coffee machines that you can set on a clock that will grind, brew and make your coffee. Can such a machine be set to brew on Shabbos? Can you set a timer to Cook on Shabbos? Would the coffee be muktza because it was just grounded?
On another note, can I set a Crock-Pot to turn on in middle of Shabbos to warm up kugel that was left on there from before Shabbos to be warm for the Shabbos meal?
Thanks.
A. Shulchan Aruch (O.H. 252: 5, 256: 1, see Shabbos 18a) rules that we are not ordained on shevisas kelim, and therefore work done automatically by utensils and implements that belong to us, without human interference during Shabbos, is basically permitted. Therein the reason for light timers, heating and A.C. equipment working on Shabbos etc.; but there are many exceptions.
One of the notable exceptions is the cooking and preparation of food. The reason is that our Sages, understanding that people are prone to personally interfere with the cooking process when in need, and that involves Biblical prohibitions, placed different restrictions and limitations as to what is permitted to be left cooking or keeping warm on a heat source, and how to make that process recognizably different.
Therefore, Horav Shlomo Miller’s Shlit’a opinion is that you should not set cooking or brewing equipment on a clock that will grind, brew and make your coffee during Shabbos.
As far as setting a Crock-Pot to turn on in middle of Shabbos, and warm up kugel that was left on there from before Shabbos to be warm for the Shabbos meal, the Rov’s opinion is that it should be avoided (as it is included in the prohibition of chazara).

Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit’a