Q&A from the Bais HaVaad Halacha Hotline

Halachic Grounds

March 19, 2026

Q May I set a coffee maker before Shabbos to grind beans and brew coffee on Shabbos morning?

A It is well established that one may set a timer before Shabbos to activate electric lights on Shabbos, even the types that involve a melacha deOreisa. The principle is that if the act that set the melacha in motion was done entirely before Shabbos, the melacha may occur on Shabbos (see O.C. 252:5; Igros Moshe, O.C. 4:60). Accordingly, one might have argued that a coffee maker programmed before Shabbos to grind beans (tochein) and brew coffee (mevasheil) on Shabbos should likewise be permitted. But doing so implicates multiple halachic issues.

One view in the Gemara (Shabbos 18a) forbids putting wheat into a water mill before Shabbos so that it grinds throughout Shabbos, because it makes noise (hashma’as kol) on Shabbos, and that issur is codified by the Rama (O.C. 252). Accordingly, causing the beans to be ground on Shabbos would be forbidden.

Chazal forbade shehiyah (placing uncooked food on a heat source before Shabbos and allowing it to continue cooking on Shabbos), lest one come to stir the coals to hasten the cooking. This prohibition applies unless the fire is rendered grufah (shoveled away) or ketumah (covered with ash; O.C. 253-254). But some hold that sealing an oven shut—or in the case of a coffee maker, taping the openings and covering the controls —could technically address this concern (see Rama 254:1; Chazon Ish, Shabbos 38:2).

The Tzitz Eliezer (2:6) cites cases where Chazal forbade melacha initiated before Shabbos because it is not visibly distinct from melacha initiated on Shabbos, e.g., placing a bowl of water under a candle to catch sparks (O.C. 265:4). The Rishonim explain that since the prohibition is not obvious, one who does it before Shabbos may come to do it on Shabbos. It is likewise not obvious that placing coffee and water into a machine even on Shabbos is forbidden if an automated process is set to begin only later. This lack of clarity is a reason for a gzeirah.

R’ Moshe Feinstein (Igros Moshe, O.C. 4:60) opposes setting ovens or similar devices to perform melachos Shabbos using timers. He distinguishes between melacha that begins before Shabbos and continues into Shabbos—like the water mill—and melacha that happens entirely on Shabbos through automation. He considers the latter to be a zilzul (denigration of) Shabbos, arguing that had such technology existed in the time of Chazal, it would certainly have been prohibited. He further suggests that this may bear a loose comparison to amirah lenachri, as one is effectively instructing an external agent to perform melacha on Shabbos.

While R’ Moshe ultimately permits the use of Shabbos clocks for lighting, he sharply limits this leniency and does not extend it to other applications (like coffee makers). In his view, even absent a definitive technical prohibition, it cannot be permitted.