initial shape of stone prior to working

The process of working a column starts with a rectangular piece of stone, the dimensions of which match the required diameter and height of the finished piece. For this example the column is without entasis, that is, the sides of the column are parallel in elevation.

marking of large chamfer onto the stone

To find the centre point from which to mark the diameter of the column, diagonal lines are marked from opposite corners on the beds of the stone. From this point dividers are used to scribe the radius of the column. Assuming that the plan of the stone is a true square equal to the diameter of the column, the circumference will touch on each edge as shown in the picture.

marking of the ovolo template onto the stone

With the diameter of the column scribed, a series of chamfers are marked on the ends using a shift stock and joined together along the length of the stone. As shown in this picture, the initial chamfers are at 45° to the face edges and touch the scribed circle. Once scribed on, these four chamfers are worked along the length of the stone.

marking of the ovolo template onto the stone

Referencing the previous picture the process of working chamfers is repeated, with each repetition doubling the number of drafts. As the number of drafts increase, their width will decrease and the column will start to become round. At a point where the drafts are about a ½" inch wide the column is at a stage where it can be tooled over with a dummy and bolster to remove high spots and give a suitable finished surface.

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