Fig. 55. Elevation of Open-Newel Stair Shown in Plan in [Fig. 54].
Everything about a stair should be made solid and sound; and every joint should set firmly and closely; or a shaky, rickety, squeaky stair will be the result, which is an abomination.
Stairs with Curved Turns.
Sufficient examples of stairs having angles of greater or less degree at the turn or change of direction, to enable the student to build any stair of this class, have now been given. There are, however, other types of stairs in common use, whose turns are curved, and in which newels are employed only at the foot, and sometimes at the finish of the flight. These curved turns may be any part of a circle, according to the requirements of the case, but turns of a quarter-circle or half-circle are the more common. The string forming the curve is called a cylinder, or part of a cylinder, as the case may be. The radius of this circle or cylinder may be any length, according to the space assigned for the stair. The opening around which the stair winds is called the well-hole.
Fig. 56. Stair Serving for
Two Flights, with Mid-Floor
Landing.
[Fig. 56] shows a portion of a stairway having a well-hole with a 7-inch radius. This stair is rather peculiar, as it shows a quarter-space landing, and a quarter-space having three winders. The reason for this is the fact that the landing is on a level with the floor of another room, into which a door opens from the landing. This is a problem very often met with in practical work, where the main stair is often made to do the work of two flights because of one floor being so much lower than another.
A curved stair, sometimes called a geometrical stair, is shown in [Fig. 57], containing seven winders in the cylinder or well-hole, the first and last aligning with the diameter.