To Set Out A Curved Mitre
Draw a section of the moulding full size, A, as shown at the left hand of the illustration, and project lines round the framing, as shown V, W, X, Y and Z. Where the lines V, W, X, Y and Z intersect at the corner D, it clearly shows that a straight mitre will not cut all the points of intersection. A curved line will cut all the intersections, and a template made of cardboard, sheet zinc, or veneer, should be made to this shape. At the left-hand side the geometrical setting out is shown for obtaining the curve without having to resort to drawing it freehand.
Take half the width of the moulding, as shown by dotted line A, and where it cuts the approximation of the curved mitre place the point of the compasses and strike out a circle as shown; with the same radius place the compass point on B—that is, the inside point of the mitre, and cut the circle on the right and left with the small arcs shown at aa. With the same radius put the compass point at the junction of the circle and mitre line, C V, and cut the circle at right and left, viz., ee.
Fig. 333.—Template for Mitreing.
Now rule a line through aa, and another line through ee, and where these lines cut each other it will give the correct radius of the curved mitre. The advantage of knowing the correct radius of a curved mitre is of great benefit to the skilled machinist, as it enables him to set up his machine so as to give a definite result.
Next: Mitreing A Moulded Door Frame
Previous: Curved Mitres