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מסכת כלים פרק יב משנה ד
מסמר הגרע

An anvil devil (a triangular length of hardened metal, it is used to cut or notch the iron that a blacksmith is forging by putting the devil on top of an anvil, then the iron on the devil, and then hammering the iron on the devil)
טמא is tamei (even though the anvil is not susceptible to tumah, it is not considered to be a part of the anvil and so has its own status),
ושל אבן השעות and [the pin] of a sundial (the sundial is of stone with the pin set in it to cast a shadow on its face and indicate the hour; others say the face of the sundial had pins set into it like the hour markers on a modern watch-face)
טהור

is tahor (as anything can be used to cast the shadow, it is not an important enough component; others say it is because it is attached to the sundial, which itself is not susceptible to tumah)
רבי צדוק מטמא Rabbi Tzadok rules it is tamei (as he holds that even though it can be replaced, the metal pin still serves the function of casting the shadow, and so has sufficient significance; others say he holds the pins that mark the hours to be the essential part of the sundial).
מסמר הגרדי The weaver's pin (this was either a thin metal pin used to move threads of the warp if they overlapped, or a length of metal that held the wooden spool of thread that went into the shuttle)
טמא is tamei,
וארון של גרוסות and the chest of gristmakers (this wooden chest was used to store their grind beans, and was particularly heavy)
רבי צדוק מטמא Rabbi Tzaddok rules is tamei
וחכמים מטהרין and the Sages rule is tahor (as, due to its heft, it was rarely moved).
היתה עגלה שלו If its wagon (used to move the gristmaker's chest)
של מתכת was of metal
טמאה it is tamei (as it does not share the status of the chest).
 

פרק יב משנה ה
מסמר שהתקינו A nail that was prepared
להיות פותח ונועל בו to unlock and lock with it (by bending and/or cutting it to fit into and turn the lock)
טמא is tamei (even though nails are ordinarily not susceptible to tumah),
העשוי לשמירה one made for for observation (i.e. by placing the nail in a spot where it will be moved by someone passing through)
טהור it is tahor (as this use is insufficiently significant).
מסמר שהתקינו And nail that was prepared
להיות פותח בו to open with it
את החבית a barrel (the nail is hardened to withstand the unusual stress of prying open a barrel)
רבי עקיבה מטמא Rabbi Akiva rules is tamei (even if the hardening process is incomplete, he holds it could still be used for this purpose)
וחכמים מטהרין and the Sages rule is tahor
עד שיצרפנו until it is hardened.
מסמר של שלחני The nail of the money-changer (this was a spike or bar inserted into the wall or post to support the money-changer's countertop)
טהור is tahor (as it is meant to be connected to a structure that is connected to the ground)
ורבי צדוק מטמא and Rabbi Tzadok ruled is tamei (because the money-changer sometimes removed it and used it for other purposes, like locking or unlocking his shop).
שלשה דברים [With respect to] three things
רבי צדוק מטמא Rabbi Tzadok ruled tamei
וחכמים מטהרין and the Sages ruled tahor:
מסמר השולחני The nail of the money-changer,
וארון של גרוסות the chest of the gristmaker
ומסמר של אבן השעות and the pin of the sundial;
רבי צדוק מטמא Rabbi Tzadok ruled tamei
וחכמים מטהרין and the Sages ruled tahor.