View source for Oseh Shtei Batei Nirin

==Definition==
# The melacha of shtei batei nirin was an essential part of the weaving processes that occurred in the construction of the Mishkan.<ref> Rashi to Shabbos 73a s.v. haPosea explains that the weaving was performed to create the curtains of the Mishkan.</ref> The process of oseh shtei batei nirin is not only complicated; the practical definition of the process is subject to a fundamental debate among the rishonim.<ref> <br />
There are three basic positions taken: 
# Rashi Shabbos 105a s.v. batei nirin seems to think that this melacha consists of stringing threads of the woof (the threads attached vertically to a loom) through the heddles of a loom (small holes which enable the weaver to lift every even or odd thread simultaneously so as to make the weaving process more efficient). For Rashi, the mechayev of this melacha would seem to be preparing the loom for the weaving process. This is the more classic understanding of Rashi (see Tosfos Yom Tov to Shabbos 7:2). However, Rashi’s shita may be slightly more complex. On daf 105a, Rashi describes another method through which one can transgress this melachahh (s.v. tarti bebatei and s.v. vachat benira). There is not sufficient space to describe this process here. Essentially, it seems that Rashi believes that one can transgress shtei batei nirin by creating the bayit (the heddle or hole) around the thread in contrast to putting the thread through the hole. If this is true, Rashi would seem to think that oseh shtei batei nirin is defined by completing a bayis with a nir drawn through it. The order of this process is irrelevant as long as you end up with a heddle and thread drawn through it, ready for the arigah process.
# The Rambam Hilchos Shabbos 9:16 has a different approach. For the Rambam, the creation of the holes (or the batim) through which the strings will be threaded is the definition of oseh shtei batei nirin. This melacha is not performed by threading the fabric through the heddle, but rather through the construction of the heddle itself. See Lechem Mishnah 9:16 and Tosfos Yom Tov Shabbos 7:2 who explicate this view of the Rambam. The Tosfos Yom Tov points out that the Mishnah’s formulation of ''oseh” shtei batei nirin implies that this melachah involves creating the batim, not placing the threads through the bayis. (It should be noted that this inference is not in contradiction with our aforementioned interpretation of Rashi. For Rashi, the definition of a beis nir could be a hole with a thread drawn through it. Therefore, creating a beis nir involves both the crafting of the bayis as well as the thread being drawn through it). While this argument will lead to significant practical ramifications regarding what will constitute a transgression of shtei batei nirin, the conceptual mechayev of the melacha seems to remain constant: the preparation of the loom for the weaving process. For these approaches, any creation of holes that will be used for the weaving process (Rambam) or any setting of strings through these holes (Rashi) will constitute a toldah transgression of shtei batei nirin. See the Rambam’s list of toldah cases in Hilchos Shabbos 9:16.
# The Meiri’s (Meiri to Shabbos 105a s.v. HaOseh shnei) interpretation of this melacha drastically differs from the approaches mentioned above. The Meiri believes that this melacha has nothing to do with setting up a loom. Rather, shtei batei nirin is a form of weaving that differs from the conventional method of weaving. The complicated process that the Meiri describes is known as “springing”, or “Egyptian Plating.” See Ma’aseh Oreg (written by Isroel Gukovitzki, London) p. 50 for an in depth description of this process. The finished product looks similar to a chain-link fence. This understanding of shtei batei nirin may shed light on the conceptual nature of meleches oreg as well (unfortunately, there isn’t sufficient space to discuss this). It is conceivable that this is a viable interpretation of the Rambam. See Markeves haMishnah Hilchos Shabbos 9:16. Also, see the Rambam’s Peirush haMishnayos Shabbos 7:2 which provides strong support for this approach to the Rambam. If this would be the case, creating any loose weave which contains holes in it (such as a net) could be a toldah transgression of this melacha. </ref>

==Links==
* [http://download.swdaf.com/DafDocs/shabbat/shabbat105_Loom.pdf Explanatory Pictures for Oseh Shtei Batei Nirin]. To properly conceptualize the facts of this case, it may be helpful to view the diagrams in Rabbi Ribiat’s 39 Melachos (vol. 3, p. 769) and in Artscroll’s Shabbos daf 105a.

==Sources==
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