On a wall this draught is made by the same principle, as at furnish of arches, only here pull a circle, instead of a semicircle or a segment.
It is slightly more difficult to extend the round socket on a ceiling. Here it is necessary between a floor and a ceiling to establish rotating rack. On a ceiling mark the circle centre. From this point lower a plumb and transfer a mark in a floor. Between them also put rotating rack on which the profile board (fig. 78 is strengthened).
a Fig. 78. Draught of the socket on a ceiling :
1 - a ceiling; 2 - polozok; 3 - a template; 4 - a rotating rack
To draught of a dome apply a template represented on fig. 79.
a Fig. 79. Draught of a dome:
1 - a ceiling; 2 - basic rejki; 3 - a template; 4 - a rotation axis
There are some more kinds of arches of a various configuration which demand more difficult geometrical construction for definition of the centres of radiuses boxes as from the several centres usually it is necessary to conduct curvilinear draughts so, from two centres pull lancet (fig. 80), from three or even from five - korobovye. Peaked arches have sites radiusnyh and rectilinear draughts. Contours of elliptic draughts, draughts of curvilinear narrowed profiles, curvilinear draughts with the centres of curvature from two parties of draught are difficult on the construction. In all these cases qualified shtukatur should have special knowledge that not only to be able to read the drawing, but also to transfer its contours on a plane.
a Fig. 80. Draught strelchatroj arches from two centres