![]() ![]() Continue until you reach the point where the keystone is to be placed. Build the arch on both sides at the same time to keep it in balance. Repeat on the other pillar.īutter another brick in the same wedge shape and place it on top of the first brick. The wedge shape of the mortar should align the brick so an imaginary line through the center of the brick would run right to the center striking point on the base of the arch form. Place the first brick or stone on top of the mortar. Place mortar like a wedge on top of one pillar with the narrow edge facing toward the inside of the arch. The frame will support the form while the bricks or stones of the arch are placed. Lift and place the half-circle plywood form on top of this support frame. Cut two lengths of lumber to go against the side pillars with the horizontal lumber resting on top of them. This piece will go under the base of the form. Build the pillars wider rather than narrower.Ĭut a horizontal length of lumber the width of the opening. ![]() The pillars should be wide and deep enough to support the arch. Nail the other half-circle plywood to the lumber.Ĭut a strip of flexible hardboard and nail it to the curved edge of the plywood.īuild two pillars on either side of the opening to a height that ends at the point where the arch begins. ![]() Nail similar pieces of lumber along the perpendicular line and two other pieces of lumber on either side of the perpendicular line to form a triangle. Use 2-by-4 lumber if the bricks or stones will be placed soldier style, or upright, along the arch and 2-by-8 if the bricks will be placed sleeping, or horizontally, with the narrow end facing out. Nail a piece of lumber on edge to the base of the half circle. These will form the two sides of the wood support form. Use the cutout shape as a template to cut a second similar shape. Starting with the keystone, use the arch's half circle to count how many bricks or stones will be needed to fill either side.Ĭut out the half circle using a power jigsaw. This is the position for the keystone, the most important stone or brick, which locks the arch into place. Mark the point where the perpendicular line bisects the half-circle arc. Keeping the string taut, place the other end on the center point and scribe a half circle from one end to the other end of the base line.ĭraw a vertical line perpendicular to the springing base line from the center point, using an L-square and a straight edge. Tie a piece of string to a pencil and place the point of the pencil on one end of the springing base line. Ashlar stone can also be used to make flat arches, in which the joints are either joggled or rebated.Find and mark the exact center of the springing base line on the bottom edge of the plywood sheet. For determining the wedged shapes of voussoirs, it is preferable to set out the arch on a level platform, marking on it the key-stone and voussoirs along with radial mortar joints. Up to depth of 60 cm, the voussoirs are made of full thickness of the arch. In this type, the stones are cut to proper shape of voussoirs, and are fully dressed, set in lime or cement joints with proper bed joints. For greater depths (thickness), rubble stones are laid in two rings in alternate course of headers and stretchers. Upto a depth of 37.5 cm, these arches are constructed in one ring. They are also used as relieving arches, over wooden lintels. Rubble arches are used upto spans of 1 m. These arches are made of rubble stones which are hammer dressed, roughly to shape and size of voussoirs of the arch and fixed in cement mortar. Rubble masonry arch is comparatively weak and is used for comparatively inferior work. Classification Based On Material And Workmanshipĭepending upon workmanship, stone arches are of two types: (i) Rubble arches, and (ii) Ashlar arches. ![]()
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