Face mold details:
Pitch In: 10.9º joint B
Pitch Out: 41.2º Joint C
Handrail C/L Radius: 88.5mm
Handrail profile: 64 X 44mm
Tangent Angle: 90º
This is the upper part for a 180º wreathing turn that goes from a 41.2º pitched flight through a 180º turn that softens to a 10.9º pitch mid-turn.
Drawing the face mold and bevels.
- 1 Plan view
- 2 Tangent pitches.
- 3 The angle of the inclined tangents.
- 4. The ordinate lines.
- 5. The handrail width.
- Stage 1 – 5 Video.
1. Plan View.
The plans may be drawn by drawing the two tangents from which the handrail will spring and the opposite sides of the box through which the handrail centre line runs on plan.
2. Tangent pitches.
With the plan view drawn, the tangent elevations may be drawn in.
A radius may be transcribed with its centre being point “A” and equal to tangent side “A – B” this may be drawn through 90º to be perpendicular with line “A – B “
This will be point “C”
The line “A – C” may then be drawn in.
From point “C” a line may be drawn at an angle equal to the lead-in angle, to intercept a line drawn from point “A” perpendicular to line “C – E”
This will be point “D”.
A line from point “D” equal to the exit pitch angle may be drawn to intercept with a line drawn from point “E” and perpendicular to the line “A – E”
This will be point “F”
3. The angle of the inclined tangents.
The angle of the inclined tangents will determine the angles between the tangent lines when drawn 2 dimensionally and laid flat.
These will be the centre lines perpendicular to the end bevels that will be used for sliding the mold, when marking the handrail blocks for cutting.
With the pitch tangents drawn above the plans view.
Strike an arc using “E” as the centre and “B” as the radius to intersect with base line “C – E” This will be point “G”
Strike an arc using “F” as the centre from point “G” through approximately 100º.
Draw an arc using “D” as the centre and “C” as the radius, draw this arc until it intersects with the previous arc draw from point “G”
This will be point “H”
Extend line “F – D” through to line “C – A”
This intersection will be point “J”
From point “A” draw a line through and perpendicular to “F – D ” extension, this should intercept at point “H”
The angle of the tangent may now be drawn in as line “D – H”
4. The ordinate lines.
The ordinate line passes through the face mold at the point where the handrail profile is perpendicular to the incline tangent and thus the same size as the width of the handrail profile.
This is the narrowest point of the face mold.
The incline tangent sides of the box may be duplicated to create the full four sided box.
Copy side “H – D” from point “D” to point “F” and side “D – F ” from point “D” to point “H”.
The ordinate line must first be found on the plan view.
To do this draw a line from point “B” to point “J”.
For the incline tangent ordinate, draw a line from point “J” to point “H”.
This is the ordinate angle, this may now be drawn over the plans and incline tangents.
To draw over the plans, copy ordinate line “B – J” from point “B” to point “O”
To draw over the incline tangents, copy ordinate line “J – H” from point “H” to point “O²”
The ordinate line from point “O” on plan or “O²” on the inclined tangent elevation will be the minor axis for the handrail ellipse on the incline elevation.
5. The Handrail width.
The handrail width may now be added to the plan view ready to be transferred up to the incline tangents.
First, offset the handrail centre line on either side by half the handrail width.
The handrail width when transferred to the elevated incline tangents over the ordinate line, will be at its plan view size or finished handrail size.
Stages 1 – 5 Video.
How to draw the plan view and inclined tangent boxes used to create the face molds for handrails with a shallow angle in and stair flight pitch angle out.
The face joint size.
The major and minor axis.
Trammel points or ellipse.
The face mold.
Making these parts – gallery.
Some images of these wreathing turns being made in the workshop.