587. Reassembling
In an introductory note to this chapter, the Kitzur Shulchan Aruch writes that most Jews are already familiar with the prohibited labors of Shabbos and that he is only addressing common situations with which people may not be familiar. Clearly, the laws of Shabbos constitute an area requiring much greater study than this email alone will allow. 80:83 Regarding objects that are made of different parts inserted into one another, if the parts became separated on Shabbos, one may reinsert them into their original form so long as the parts are normally joined together loosely. If the parts are normally joined tightly, we may not reinsert them even loosely. (This is a rabbinic prohibition instituted as a preventive measure against completing a utensil, which is not a concern when it comes to things that are assembled only loosely - Mishnah Brurah 313:41-42.) If the pieces are connected by screws, because they are normally held together tightly, if they separate, one may not reattach them, even loosely. The covers of utensils may be removed and replaced on Shabbos because they are designed to be opened and closed regularly.
80:84 A press is two parallel boards, between which one flattens out his clothes. A household press may be opened to remove clothes that one needs for Shabbos or yom tov, though one may not use it to press his clothes since this is considered for a weekday need. The press of a laundryman or of another professional craftsman may not even be opened on Shabbos. This is because the boards of a professional press are clamped together tightly so that opening it constitutes an act of dismantling. One may not take clothes from a professional press even if it was opened (slightly - MB 302:21) before Shabbos or yom tov. This is a rabbinical safeguard instituted out of the concern that one may come to open a press that is not ajar. (If the press was completely open before Shabbos or yom tov began, we may remove clothes from it on Shabbos or yom tov - Mishnah Brurah ibid.)