In laying out the steps for the turnout observe the same rule that applies to all winding stairs, that is, to make them as near the width of the straight treads as possible on the waiting line. Locate the landing riser exactly half a step from the center of rail on landing, as shown at Stair Parts Fig.15. This will bring the rail the same height on landing as it is in the middle of the step. Any departure from this rule will either change the height or will make it necessary to spring the wreath or slab off the shank, a very clumsy experiment.
Stair Parts Fig.15 shows the plan of turnout 'steps, with rail mitering into cap. The dotted curved line shows face of string. The black line shows center of rail with tangent ABC at right angles to dotted radius.
Stair Parts Fig. 15
Stair Parts Fig. 16 shows the tangents in position on the pitch. To construct Fig. 0, take the pitchboard and mark out the steps as shown. Beginning at third riser and coming down, draw pitch-line CB from second riser D; mark distance DE, which gives angle B; draw level tangent BA, agreeing with BA, Fig. 15; continue line of first step with dotted line to F, draw FC; continue the line AB to G. The distance from G to C is the required height, and EB gives the height to which the rail is lifted at the newel.
Stair Parts Fig. 16
To construct Stair Parts Fig. 17, draw tangents ABC, and curve line exactly like Fig. 15. In practice this figure can be drawn on Fig. 15, and to avoid confusion of lines it is transferred. Continue AB to D; draw DC at right angles to DB; -set up the height, GC, Fig. 16. Connect ED at right angles to ED, draw DF; with D as center, describe an arc from B to G and from A to F, then connect EG; draw dotted ordinates AA to mark center of curve and chord line. The spring bevel for squaring the wreath at lower end is found at angle E. To obtain the bevel for upper joints take a center anywhere on line ED, describe an arc touching EG and cutting ED at H. Draw line from center of arc at right angles to ED, cutting EC at I. Connect HI, and the angle at H is the upper spring bevel.
Stair Parts Fig. 17
The development of pitch-Line for wreath is shown at Stair Parts Fig. 18. First make a plan of the cylinder; draw center line of rail with tan gents CAB (the distance from face of string to center of rail. varies' according to size of baluster), locate the risers, putting last one-half step from angle A, locate the joint of rail at riser C. With A for a center describe the arc ACD, extend AB to D, swing last riser around to E, chord line H, and X to I. Place pitchboard with riser touching AC, and hypothenuse or raking side cutting through E; draw pitch-line and continue AC to meet it at F. AF is the height of rail above the floor; draw FG at right angles to FC; continue radius 0 through to G, square up from I to pitch line and from H and D down.
Stair Parts Fig. 18
To construct Stair Parts Fig. 19 (this figure can be drawn on Fig. 18, but is transferred for the same reason as Fig. U), draw a line agreeing exactly with pitch-line DF, with points HEI marked; make FG at right angles to DF, and equal to FG, Fig. 18. Draw the line I equal to X, Fig. 2, bend in a thin strip of wood and draw curve GIH. Set off half the width of rail on each side of this curie line, square the joints from the tangents KFG, and the mould is completed. A little more than the finished size of rail is necessary to square the wreath, but not often more than one-eighth of an inch on each side. The surest way is to draw the spring bevel on a board, place a templet the size of the rail on a bevel line at right angles to it, square from the edge of board across corners, draw, parallel lines enclosing the templet, and it will be seen at once how wide the mould should be and what thickness of plank is required. This method is seen in application of bevels at Figs. 21 and 22.
Stair Parts Fig. 19, 20
Stair Parts Fig. 20 shows the bevel portion of wreath; a better appearance is given to the wreath by using plank half an inch thicker than the rail, and casing it up from center joint as shown by the sections on end of mould.
Stair Parts Figs. 21 and 22 show the application of the spring bevels and templets for squaring the wreaths.
Stair Parts Fig. 21, 22
The bevel for Stair Parts Fig. 21 is found at F, and is simply the pitch of the stairs. The bevels for the turnout wreath are both applied in the same manner, from the inside, or the face cutting through the center, as shown by the sections.
The following illustrations exhibit a method of obtaining the face moulds for the flight of stairs shown at Fig. 2, which is a flight the most common in use.
To obtain dimensions make the plan, etc., and follow the instructions given for Stair Parts Fig. 1. Where the risers are located half a step from center of rail, as explained previously, the same method will apply to this flight, and the bevel will be the pitch of the stairs at the center point, and the section will be square with the face of stuff at the straight end of wreath.