Home >> Encyclopedia-of-architecture-1852 >> Portic1 to Sir Christopher Wren >> Sasit Frame_P1

Sasit-Frame

boxing, edge, inside, distance, inches, lining, sash-frame, folds, breadth and head

Page: 1 2

SASIT-FRAME, the wooden frame in which the sashes are fitted for the convenience of sliding up or down, or sideways, as the nature of the apartment to be lighted may require.

. When one or both sashes are to be moved vertically, they are commonly equipoised by weights ; and the are made to run in vertical trunks, or cases, formed in the sides of the frames, which are therefore said to be eased ; but when the sides are not made hollow for weights, the frame is said to be solid. In a sash-frame, the under side of the head is most commonly disposed in the same surface as the soffit, or intrados, of the stone or brick head of the window on the outside ; consequently, it partakes of the shape of the head of the window, whether straight or circular. In a cased sash-frame, each ease consists of four pieces ; the inside piece, on each side, or that next the aperture, is most commonly dis posed in the same plain with the jamb of the stone, or side of the aperture, on the outside, the two sides forming parallel planes : these two pieces are called from their containing the pulleys, over which the ropes pass, by which the sashes and weights are suspended. The other three parts of each trunk are called linings ; that parallel to the pulley-piece, and next to the jamb, on either side, is called the back ; the one next the outside, and parallel to the face of the wall, is the outside lining ; and the remaining one next to the inside of the room, is denominated the inside lining. The best-made sash.frames have the pulley-pieces tongued into the outside and inside linings; the back lining is generally tongued into the outside, and nailed to the edge of the inside lining ; on each pulley-piece two channels, of equal breadth, for the edges of the sashes to run in, are formed by nailing a slip of wood round the inner margin of the pulley-piece, and suffering the outside lining to project within it ; between which a narrow slip is inserted in a groove, left in the middle of the-intervening space. As the edge of this slip is generally rounded, it is called the parting bead ; and the inner slip, for the same reason, is termed the inside bead ; while the edge of the outer lining is called the outside bead. Within the case, there is also a vertical slip, suspended from the head, and passing longitudinally through the middle of the hollow space, for separating the two weights, which is therefore called the parting slip. The head, sill, and inside linings, have generally each a groove next to the inside of the room ; the groove in the head and sill is commonly three.eighths of an inch from the edge next to the opening ; that in the head is for inserting the edge of the soffit, and that in the sill for receiving the edge of the capping bead, upon the upper edge of the back. The grooves, in the inside lining, are for the edges of the back lining of the boxing ; the distance of these grooves from the niner edge of the inside depends on the depth of the boxing, and the distance of each line of hinges front the inner edge of the inside lining, or of that next to the opening. The line of hinges is gene rally about three-eighths of an inch from the inner edge of the inside lining ; so that the shutters, soffit, and capping bead, may have their terminating edges with the sash-frame of the same margin all round ; that is, at the same distance as the inner edge of the sash-frame ; this, however, is not positively necessary, but may be varied at the discretion of the archi tect or workman. The line of hinges being determined, the

depth of the boxing is found by adding to the thickness of the wall that of the inside finishing, whether of plaster alone, or of lath and plaster (the former requiring about an inch and the latter 21- inches); and subtracting from the sum, the thickness of the sash-frame, and its distance from the outside of the wall ; then, if the remainder be equal to, or exceed half the distance of the hinge-lines, such half distance is the breadth of both the boxing and the shutter ; it must, how ever, be observed, that the outer edge of the shutter must not be rebated, as that would prevent the edges of both coining close to the architrave, or margin style which forms the side of the boxing, opposite to the inner lining of the sash-frame, when each shutter consists of one piece only ; to remedy this, each shutter must either consist of two folds, viz., a front part, and a back flap ; and the breadth of the boxing must be contracted, either by introducing a margin style at the edge of each boxing ; or, if one was necessary before, by making it broader ; then the thickness of the two folds will be the neat distance of the groove from the line of hinges. It on the other hand, the remainder, before men tioned, be less than the half distance between the hinge lines, it is the breadth of the boxing ; divide the half distance between the hinge lines, by the breadth of the boxing, and the quotient will give the number of folds ; and if there be a remainder, there must be one fold more than is shown by the quotient. The aggregate, or sum of all the folds, is the neat depth of the boxing : but, in order to make the folds clear each other and the back of the boxing, add the eighth or tenth part of an inch for each fold. Thus, suppose the wall to be of eighteen-inch brickwork, and the finishing within to be lath and plaster ; suppose, also, the breadth of the window to be 4 feet, the sash-frame 6 inches thick, and its distance from the wall 4 inches : then, 201 inches is the thickness of the wall and finishing ; the thickness of the sash-frame and its distance from the face of the wall are, together, 10 inches; this, taken from 20- inches, gives 101- inches for a remainder, which is the breadth both of the boxing and of the shutter, because 101 inches are less than 24 inches, the half distance between the lines of hinges : 10.1- is contained twice in 24 inches with a remainder ; there are, therefore, three folds, viz., a front fold and two back flaps ; suppose the front fold to be 14- inch thick, each back 11- inch thick ; then 14411 +11=-1 inches ; and because there are three folds, add -g of an inch more, and the depth of the boxing will be 4-g- inches. Sash-frames are made in Dublin with half-sills.

Page: 1 2