What Can One Shecht With?
1. According to the Gemara, one may shecht with anything detached from the ground, e.g., a stone, glass, or wood, if it is sharp and has no nicks (גמ' חולין דף ט"ז ע"ב, שו"ע יו"ד סי' ו' ס"א ).
2. Only metal. However, the minhag in Jewish communities everywhere is to shecht only with a metal knife (פמ"ג שם שפ"ד סק"ב). In our generation and the previous generation, the minhag became to only shecht with a good, high-quality iron knife (בית דוד, יסוד הבית סי' ח"י סק"א ). The better the iron, the stronger, sharper, and smoother the knife is. Also, it does not get ruined after a shechita. The shochet must be skilled at sharpening the knife and maintaining its good condition. Just as you can’t have a craftsman without tools, you also can’t have tools without a craftsman (בית אברהם ס"ו סק"ב ).
3. The word “chalef.” The shechita knife is called a “chalef.” The simple reason is because the Latin word for large knives is chalafim; that is why the room in the Beis HaMikdash where the knives were stored was called the בית החליפות (רע"ב מדות פ"ד מ"ז). The posuk also says (עזרא א, ט'), “מחלפים תשעה ועשרים ” (ע"פ רש"י שם ).
4. Other reasons are also given: 1) The knife “transfers” [מחליף] the animal from life to death; 2) The knife goes back and forth, and the word חלף in the posuk in Shir HaShirim (ב', י"א ) [“הגשם חלף הלך לו”] conveys a similar concept; 3) חלף stands for גום פ א ל ד ח [sharp, not nicked] (מהר"ץ ).
Toiveling a New Knife
5. The Mechaber holds that a shochet does not need to toivel a new knife he buys from a non-Jew since it is not a utensil used at a meal, as the animal is not edible before it is cooked (שו"ע יו"ד סי' ק"כ ס"ה ). However, the Rama’s opinion is that it is proper to toivel it without a bracha (רמ"א שם ); this is the Ashkenazi minhag.
